
MP3 is a popular digital audio encoding and lossy data compression audio compression format. It was designed to greatly reduce the amount of data (10:1 compression is common) required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. In popular usage, MP3 also refers to files of sound or music recordings stored in the MP3 format on computers. The name is derived from "MPEG-1 Audio Layer 3", more formally known as "MPEG-1 Part 3 Layer 3" or "International Organization for Standardization/International Electrotechnical Commission 11172-3 Layer 3". Reportedly, the ".mp3" filename extension is also sometimes used on audio files encoded using the newer "MPEG-2 Audio Layer 3" standard (a.k.a. "MPEG-2 Part 3 Layer 3" or "International Organization for Standardization/International Electrotechnical Commission 13818-3 Layer 3"). == Overview == MP3 is a lossy data compression format. It provides a representation of pulse-code modulation-encoded (PCM) audio data in a much smaller size by discarding portions that are considered "less important" to human hearing. (This is similar in concept to JPEG lossy compression for images.) A number of techniques are employed in MP3 to determine what portions of the audio can be discarded, including psychoacoustics. MP3 audio can be compressed with different bit rates, providing a range of tradeoffs between data size and sound quality. MP3 Surround, a version of the format supporting 5.1 channels, was introduced in December 2004. MP3 Surround is backward compatible with standard stereo MP3, and file sizes are similar. The MP3 format uses, at its heart, a hybrid transform to transform a time domain signal into a frequency domain signal: * 32 band polyphase quadrature filter * 36 or 12 tap MDCT, size can be selected independent for subband 0...1 and 2...31 * aliasing reduction postprocessing In terms of the MPEG specifications, Advanced audio coding (AAC) from MPEG-4 is to be the successor of the MP3 format, although there has been a significant movement to create and popularize other audio formats. Nevertheless, any 'succession' is not likely to happen for a significant amount of time due to MP3's overwhelming popularity. MP3 enjoys extremely wide popularity and support, not just by end-users and software but by hardware such as DVD and CD players. ==History== ===Development=== MPEG-1 Audio Layer 2 encoding started life as the Digital Audio Broadcast (DAB) project initiated by the Fraunhofer Society. This project was financed by the European Union as a part of the EUREKA research program where it was commonly known as EU-147. EU-147 ran from 1987 to 1994. In 1991, there were two proposals available: Musicam (known as Layer II) and ASPEC (Adaptive Spectral Perceptual Entropy Coding) with similarities to MP3. Musicam was chosen due to its simplicity and error robustness. A working group around Karlheinz Brandenburg and Jürgen Herre took ideas from Musicam and ASPEC, added some of their own ideas and created MP3, which was designed to achieve the same quality at 128 kbit/s as MP2 at 192 kbit/s. Both algorithms were finalized in 1992 as part of MPEG-1, the first standard suite by MPEG, which resulted in the international standard International Organization for Standardization/International Electrotechnical Commission 11172-3, published in 1993. Further work on MPEG audio was finalized in 1994 as part of the second suite of MPEG standards, MPEG-2, more formally known as international standard International Organization for Standardization/International Electrotechnical Commission 13818-3, originally published in 1995. Compression efficiency of lossy compression encoders is typically defined by the bit rate because compression rate depends on bit depth and sampling rate of the input signal. Nevertheless, there are often published compression rates which use the compact disc parameters as references (44.1 kHz, 2 channels at 16 bits per channel or 2x16 bit). Sometimes the Digital Audio Tape (DAT) SP parameters are used (48 kHz, 2x16 bit). Compression ratios for this reference is higher, which demonstrates the problem of the term "compression ratio" for lossy encoders. Karlheinz Brandenburg used a CD recording of Suzanne Vega's song "Tom's Diner" as his model for the MP3 compression algorithm. This song was chosen because of its softness and simplicity, making it easier to hear imperfections in the compression format during playbacks. === MP3 went public === On the 7th July 1994 the Fraunhofer Society released the first software MP3 encoder called l3enc. With the first realtime software MP3 player Winplay3 (released 9th September 1995) people were able to encode and playback MP3 files on a PC. Because of the relative small harddrives back in that time (usually about 512 MB) the technology was essential to store music for listening pleasure on a computer. === MP2 and MP3 and the Internet === In October 1993, MP2 ("MPEG-1 Audio Layer 2") files appeared on the Internet and were often played back using "Xing MPEG Audio Player", and later in a program for Unix by Tobias Bading called MAPlay initially released on February 22, 1994. (MAPlay was also ported to Microsoft Windows.) Initially the only encoder available for MP2 production was the Xing Encoder, accompanied by the program CDDA2WAV, a CD ripper that copied CD audio to hard disks. Internet Underground Music Archive (IUMA) is generally recognized as the start of the on-line music revolution. IUMA was the Internet's first high-fidelity music web site, hosting thousands of authorized MP2 recordings before MP3 or the web were popularized. IUMA was started by Rob Lord (who later headed pioneering Nullsoft) and Jeff Patterson, both from University of California, Santa Cruz, in 1993. Other founding members include Jon Luini, Brandee Selck and Ahin Savara. In the first half of 1995, MP3 files began flourishing on the Internet. Its popularity was mostly due to, and interchangeable with, the successes of companies and software packages like Nullsoft's Winamp, mpg123 and (now Roxio-owned) Napster. Those programs made it very easy to playback, create, share and collect MP3s for the average PC users. Controversies regarding peer to peer file sharing of MP3 files have flourished in recent years — largely because high compression enables sharing of files that would otherwise be too large and cumbersome to share. Due the vastly increased spread of MP3s through the internet some major record labels reacted by filing a Napster#Legal_challenges. Since 2003, the number of MP3 blogs has exploded, while largely avoiding a backlash from record companies. Commercial online music distribution services (like ITunes Music Store) usually prefer other music file formats that support DRM to control and restrict the use of digital music. ==Quality of MP3 audio== Many listeners accept the MP3 bitrate of 128 kilobit per second (kbit/s) as near enough to compact disc quality for them. This provides a compression ratio of approximately 11:1, although listening tests show that with a bit of practice, many listeners can reliably distinguish 128 kbit/s MP3s from CD originals. To some listeners, 128 kbit/s is unacceptably low quality. Even though differences may be perceptible, this is acceptable for some listeners in some listening environments, such as a noisy car or train. Fraunhofer Gesellschaft (abbreviated FhG) publish on their official webpage the following compression ratios and data rates for MPEG-1 Layer 1, 2 and 3, intended for comparison: * Layer 1: 384 Kilobit per second, compression 4:1 * Layer 2: 192...256 kbit/s, compression 6:1...8:1 * Layer 3: 112...128 kbit/s, compression 10:1...12:1 These values are probably overly optimistic (they are likely to be influenced by public relations) because the quality depends not only on the encoding file format, but also on the quality of the psychoacoustic algorithms used by the encoder. Typical layer 1 encoders use simple psycho acoustics which result in a higher needed bit rate for Transparency (data compression) encoding. * Layer 1 encoding at 384 kbit/s, even with these simple psychoacoustics, is better than Layer 2 at 192...256 kbit/s * Layer 3 encoding at 112...128 kbit/s is worse than Layer 2 at 192...256 kbit/s. That is to say, the assumed bit rates are not equivalent in quality and the qualities are not necessarily optimal (it is generally agreed that 112 to 128 kbit/s Layer 3 is not excellent sound) and therefore the comparison is probably not reliable as an objective source. More realistic bit rates are: * Layer 1: excellent at 384 kbit/s * Layer 2: excellent at 256...384 kbit/s, very good at 224...256 kbit/s, good at 192...224 kbit/s * Layer 3: excellent at 224...320 kbit/s, very good at 192...224 kbit/s, good at 128...192 kbit/s Comparing a new file format typically is done by comparing a medium quality encoder of the old format and a highly tuned encoder of the new format. A few possible encoders: * LAME first created by Mike Cheng in early 1998, it is a (by contrast to others) fully LGPL'd MP3 encoder, with excellent speed and quality, rivaling even MP3's technological successors. * Fraunhofer Gesellschaft: Some encoders are good, some have bugs. Some early encoders are not widely used any more: ISO dist10 reference code, Xing, BladeEnc, and ACM Producer Pro. The quality of MP3 files depend on the quality of the encoder and the difficulty of the signal which must be encoded. *Good encoders produce acceptable quality at 128 to 160 kbit/s and near-Transparency (data compression) at 160 to 192 kbit/s. *Low quality encoders may never reach transparency, not even at 320 kbit/s. So it is pointless to speak of 128 kbit/s or 192 kbit/s quality, except in the context of a particular encoder or of the best available coders. A 128 kbit/s MP3 produced by a good encoder might sound better than a 192 kbit/s MP3 file produced by a bad encoder. Additionally, it is important to note that this is subjective. A given bitrate suffices for some listeners but not for others. The numbers given above are rough guidelines that work for many people, but in the field of lossy audio compression, the only true measure of the quality of a compression process is to listen to the results. An important feature of MP3 is that it is lossy — meaning that it removes information from the input in order to save space (and bandwidth cost in transferred). As with most modern lossy encoders, MP3 algorithms work hard to ensure that the parts it removes cannot be detected by human listeners by modeling characteristics of human hearing (i.e., noise masking). The importance of this is that it can gain huge savings in storage space with reasonable and acceptable (although detectable) losses in fidelity. If your aim is to archive sound files with no loss of quality (or work on the sound files in a studio) you should consider lossless data compression such as: *FLAC (FLAC) *Monkey's Audio (APE) *Shorten (SHN) *Lossless Predictive Audio Compression (LPAC) *Wavpack (WV) *TTA (TTA) *Apple Lossless These are capable of compressing 16-bit PCM audio to 38 to 80% of its original size (depending upon the characteristics of the audio itself), leaving the audio bit-for-bit identical to the original (ergo "lossless"). It is important to understand the difference between audio for further processing and audio use only for playback. Lossless formats are strongly preferred for material which will be edited, mixed, or otherwise processed because the perceptual assumptions made by lossy coders may not hold true after processing. Most people find lossy coders acceptable for audio which will only be played. Nevertheless, individual acoustic perception may vary so it is not evident that a certain psychoacoustic model can give satisfactory results for everyone. Merely changing the conditions of listening, such as the audio playing system or environment, can expose unwanted distortions caused by lossy compression. Lossless formats will produce the best possible result, at the expense of a lower compression ratio. If MP3 audio needs to be decoded and re-encoded another time, for example when it will be aired on radio, cascading lossy compression stages can significantly reduce the quality of the end-result. To prevent this, keep audio data in its original state if further operating on it is necessary. If any operation needs to be done on MP3 data, such as cutting or merging audio, or lowering bitrate, it is preferable to use software that works directly with the encoded data (such as mp3DirectCut and MP3Gain) and prevent extra decoding-encoding steps. ==Bit rate== The bit rate is variable for MP3 files. The general rule is that the higher the bitrate, the more information is included from the original sound file, and thus the higher the quality of played back audio. In the early days of MP3 encoding, a fixed bit rate was used for the entire file. Bit rates available in MPEG-1 layer 3 are 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256 and 320 kibit/s, and the available sample frequencies are 32, 44.1 and 48 kHz. 44.1 kHz is almost always used (coincides with the sampling rate of compact discs), and 128 kbit has become the de facto "good enough" standard, although 192 kbit is becoming increasingly popular on peer-to-peer file sharing programs. MPEG-2 and (the non-official) MPEG-2.5 adds more bitrates: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 kbit/s. As already mentioned, variable bit rates (VBR) are also possible. Audio in MP3 files are divided into frames (which have their own bit rate) so it is possible to change the bit rate dynamically as the file is encoded. This was not originally done, but VBR is in extensive use today. This technique makes it possible to use more bits for parts of the sound with high dynamics (much "sound movement") and fewer bits for parts with low dynamics, increasing quality and decreasing storage space further. This method compares to a sound activated tape recorder which saves the tape space from when silence was prevalent for the times when sound is being heard. Some encoders utilize this technique to a great extent. ==Design limitations of MP3== There are several limitations inherent to the MP3 format that cannot be overcome by using a better encoder. More recent audio-compression formats such as Vorbis, advanced audio coding, Musepack and WMA no longer have these limitations. In technical terms, MP3 is limited in the following ways: * In constant bitrates, bitrates are limited to a maximum of 320 kbit/s * Time resolution can be too low for highly transient signals * Encoder/decoder overall delay is not defined * No scaleband factor for frequencies above 15.5/15.8 kHz * Joint stereo is done on a frame-to-frame basis Nevertheless a well-tuned MP3 encoder can perform competitively even with these restrictions. ==Encoding of MP3 audio== The MPEG-1 standard does not include a precise specification for an MP3 encoder. The decoding algorithm and file format, as a contrast, are well defined. Implementors of the standard were supposed to devise their own algorithms suitable for removing parts of the information in the raw audio (or rather its Modified discrete cosine transform representation in the frequency domain). This is the domain of psychoacoustics, which aims at understanding how human acoustical perception works (both in our ears and in our brain). As a result, there are many different MP3 encoders available, each producing files of differing quality. Comparisons are widely available, so it is easy for a prospective user of an encoder to research the best choice. It must be kept in mind that an encoder that is proficient at encoding at higher bitrates (such as LAME, which is in widespread use for encoding at higher bitrates) is not necessarily as good at other, lower bitrates. ==Decoding of MP3 audio== Decoding, on the other hand, is carefully defined in the standard. Most decoders are "bitstream compliance", meaning that the uncompressed output they produce from a given MP3 file will be the same (within a specified degree of rounding tolerance) as the output specified mathematically in the standard document. Therefore, for the most part, comparison of decoders is almost exclusively based on how computationally efficient they are (i.e., how much computer memory or CPU time they use in the decoding process). ==ID3 and other tags== :''See main articles ID3 and APEv2 tag'' A "tag" is data stored in an MP3 (as well as other formats) which contains metadata such as the title, artist, album, track number or other information about the MP3 file to be added to the file itself. The most widespread standard tag formats are currently the ID3 ID3v1 and ID3v2 tags, and the more recent APEv2 tag. APEv2 was originally developed for the MPC (audio compression format) (see [http://www.personal.uni-jena.de/~pfk/mpp/sv8/apetag.html the APEv2 specification]). APEv2 can coexist with ID3 tags in the same file, but it can also be used by itself. ==Volume normalization== As compact discs and other various sources are recorded and mastered at different volumes, it is useful to store volume information about a file in the tag so that at playback time, the volume can be dynamically adjusted. A few standards for encoding the gain of an MP3 file have been proposed. The idea is to normalize the volume (not the volume ''peaks'') of audio files, so that the volume does not change between consecutive tracks. The most popular and widely-used solution for storing replay gain is known simply as "Replay Gain". Typically, the average volume and clipping information about an audio track is stored in the metadata tag. ==Alternative technologies== Many other lossy audio codecs exist, including: * MP2 (format) (MP2), MP3's predecessor; * Ogg Vorbis from the Xiph.org Foundation, a free software and patent free codec. * MPC (audio compression format), also known as Musepack (formerly MP+), a derivative of MP2; * mp3PRO from Thomson Multimedia combining MP3 with Spectral Band Replication; * AC-3, used in Dolby Digital and DVD; * ATRAC, used in Sony's Minidisc; * MPEG-4 Advanced audio coding, used by Apple Computer's iTunes Music Store and iPod * Windows Media Audio (WMA) from Microsoft. * QDesign, used in QuickTime at low bitrates; * AMR-WBplus Enhanced Adaptive Multi Rate WideBand codec, optimized for cellular and other limited bandwidth use; * RealAudio from RealNetworks, frequently in use for streaming on websites; * Speex, free software and patent free codec based on CELP specifically designed for speech and VoIP. mp3PRO, MP3, AAC, and MP2 are all members of the same technological family and depend on roughly similar psychoacoustic models. The Fraunhofer Gesellschaft owns many of the basic patents underlying these codecs, with Dolby Labs, Sony, Thomson Consumer Electronics, and ATT holding other key patents. There are also some non-lossy (lossless data compression) audio compression methods used on the Internet. While they are not similar to MP3, they are good examples of other compression schemes available. These include: * FLAC stands for 'Free Lossless Audio Codec' * Monkey's Audio * SHN, also known as Shorten * TTA * Wavpack Listening tests [http://www.rjamorim.com/test/] have attempted to find the best-quality lossy audio codecs at certain bitrates. The tests have suggested that for some audio samples, newer audio codecs including Ogg Vorbis, mp3PRO, AC-3, Windows Media Audio, MPC and RealAudio perform better than MP3. Generally, these codecs achieve the equivalent of MP3 128kbps at around 80kbps. At 128kbps, Ogg Vorbis and MPC performed marginally better than other codecs. At 64kbps, ACC and mp3pro performed marginally better than other codecs. At high bitrates (128kbps+), most people do not hear significant differences. What is considered 'CD quality' is quite subjective; for some 128kbps MP3 is sufficient, while for others 192kbps MP3 is necessary. Though proponents of newer codecs such as WMA and RealAudio have asserted that their respective algorithms can achieve CD quality at 64 kbit/s, listening tests have shown otherwise; however, the quality of these codecs at 64 kbit/s is definitely superior to MP3 at the same bandwidth. The developers of the patent-free Ogg Vorbis codec claim that their algorithm surpasses MP3, RealAudio and WMA sound quality, and the listening tests mentioned above support that claim. Thomson claims that its mp3PRO codec achieves CD quality at 64 kbit/s, but listeners have reported that a 64 kbit/s mp3PRO file compares in quality to a 112 kbit/s MP3 file and does not come reasonably close to CD quality until about 80 kbit/s. MP3, which was designed and tuned for use alongside MPEG-1/2 Video, generally performs poorly on monaural data at less than 48 kbit/s or in stereo at less than 80 kbit/s. ==Licensing and patent issues== Thomson SA controls licensing of the [http://www.mp3licensing.com/patents/index.html MPEG-1/2 Layer 3 patents] in countries such as the United States and Japan that recognize software patents. Thomson has decided to attempt to collect royalties for the patents. In September 1998, the Fraunhofer Institute sent a letter to several developers of MP3 software stating that a license was required to "distribute and/or sell decoders and/or encoders". The letter claimed that unlicensed products "infringe the patent rights of Fraunhofer and THOMSON. To make, sell and/or distribute products using the [MPEG Layer-3] standard and thus our patents, you need to obtain a license under these patents from us." These patent issues significantly slowed the development of unlicensed MP3 software and led to increased focus on creating and popularising alternatives such as WMA and Ogg Vorbis. Microsoft, the makers of the Windows operating system, chose to move away from MP3 to their own proprietary Windows Media formats to avoid the licensing issues associated with the patents. Until the key patents expire, open source / free software encoders and players appear to be illegal for commercial use in countries that recognize software patents. For information about licensing fees see [http://www.mp3licensing.com/help/developer.html] and [http://www.mp3licensing.com/royalty/index.html]. In spite of the patent restrictions, the perpetuation of the MP3 format continues; the reasons for this appear to be the network effects caused by: * familiarity with the format, not knowing alternatives exist, * the large quantity of music now available in the MP3 format, * the wide variety of existing software and hardware that takes advantage of the file format that revolutionized the music industry and copyright law. == Online music resources == Tools such as iRate try to make it easier to find music that matches the listener's tastes. There are several online music stores. Apple's iTunes Music Store store is presently the most popular commercial online music offering. Independent artists are able to use smaller sites to provide distribution. A controversial MP3 portal is the Russian site AllOfMP3.com, which offers downloads of thousands of albums and video clips by mainstream artists, priced at $20 per gigabyte. There are also several online columnists who edit news sites focused on digital music and the grassroots community it spawned. They include Richard Menta's [http://www.mp3newswire.net MP3newswire.net], an early MP3 news site started in 1998, Jon Newton's [http://www.p2pnet.net P2Pnet], and Thomas Mennecke's [http://www.slyck.com Slyck.com]. Other sites like Download.com and Vitaminic.com which allow artists to choose to post their own music for free download. ==See also== *ID3 *Digital audio player *Media player *Software patent ==External links== * [http://www.iis.fraunhofer.de/amm/techinf/layer3/ Fraunhofer IIS] * [http://www.mp3licensing.com/patents/index.html List of relevant patents] * [http://mpgedit.org/mpgedit/mpeg_format/MP3Format.html MP3 File Format Specification] * [http://www.tnt.uni-hannover.de/project/mpeg/audio/ MPEG Audio Web Page] * [http://www.tnt.uni-hannover.de/project/mpeg/audio/faq/ MPEG Audio FAQ] * [http://mp3.ithaki.net/ MP3 Search Engine - Finds MP3 files] * [http://www.id3.org/ ID3v2 Information] * [http://www.mp3-news.net/ News about the MP3 format] * [http://www.mp3licensing.com Thomson's mp3licensing.com] * [http://www.xiph.org/ogg/vorbis/listen.html Xiph.org listening test] - Vorbis vs. MP3, RealAudio, Windows Media, etc. * [http://www.rjamorim.com/test/ Roberto's public listening tests] - blind, controlled listening tests of lossy compression formats including MP3. * [http://www.codingtechnologies.com/ Coding Technologies (DAB related)] * [http://www.factum.se/ Factum Electronics (DAB related)] * [http://www.mp3-tech.org/content/?Mp3%20Limitations Mp3 Limitations] - LAME developer explains flaws and restricitons of MP3 compared to newer formats ===Software links=== * [http://mitiok.ma.cx/ LAME MP3 Encoder downloads] * [http://www.rarewares.org/mp3.html Rarewares MP3 software downloads] * [http://www.mpesch3.de/ mp3DirectCut, for fast mpeg audio editing] * [http://mp3gain.sourceforge.net/ MP3Gain, changes audio-level of mp3 files] * [http://www.mpeg.org/MPEG/audio.html MPEG Audio Resources and Software] * [http://mplib.sourceforge.net/ mp3 tagging library (software)] * [http://www.id3-tagit.de ID3 tag + filename manipulation software] (ID3 is the tagging system used to store information about tracks in the MP3 files) Audio codecs Digital audio Digital Revolution Digital media Computer file formats
==MPEG-I/II== In the first line it says "MPEG-1/2", and this needs to be explained on the page, I think. Here's what I know about it: Phase 1 can handle input streams (or WAV files) with a sample frequency of 48000, 44100 or 32000 Hz and is therefore used most often, obviously. Phase 2 will only support stream for 24000, 22050 and 16000 Hz. Basically, Phase 2 is intended for lower bit rates (e.g. for voice communication, or if you need small files with reduced quality, podcasts and live online audio-feeds and the likes). The lowest bit-rate for Phase 2 is 8 kBits/sec while for Phase 1 the lowest bit rate is 32 kBits/s. User:195.64.95.116 23:11, 11 Mar 2005 (UTC) :Response to User:195.64.95.116: There are several problems in the above comments. Please refer to an authoritative source such as [http://www.chiariglione.org/mpeg/ The official MPEG site] or [http://www.mpegif.org The MPEG Industry Forum site] or perhaps the somewhat less official [http://www.mpeg.org MPEG.ORG site]. Be very careful to only get your information from such reliable sources, as there is a significant amount of confusion found on more random web sites. Do not call the MPEG-X numerical suffixes "Phases". Do not use roman numerals to denote them. MP3 originated from MPEG-1 Audio Layer 3, also properly referred to as MPEG-1 Part 3 Layer 3 (where "Part 3" refers to audio coding, "Part 1" is multiplexing, "Part 2" is video coding, etc.). The stuff above about sample frequency looks wrong too. I'm not personally aware of any connection between MP3 and MPEG-2, except for the former being a predecessor of the latter. User:Pangolin 06:16, 12 Mar 2005 (UTC) ::Actually, it is exactly the other way around; You have to call the old MPEG-X Phases, since they are, and always have been. .MP2 and .MP3 used to both even be called .MPA and this was way before the Part 1 or Layer 3 issues came into play. Hey, I know, because I was there testing and using it back in the day. I don't really care what you think it should be, I know what the Phases meant, why they are there in the format, and when they started putting it in. The "Part 1" came into play because of incompatibility with Part 2, which is different from Phase 1 and Phase 2. MP3 originated from MPA, which in turn changed to MPEG Phase 1 Layer 3. To help make it clear, it was decided by its creators (hey, ask them) to use the Roman for the Layers. Furthermore, I don't know what fool put in the MPEG-2 part about 'the new' MP3, but that's a silly thing to do; That new MPEG-2 is not the same as MP2, the new MPEG-2 is no longer describing the Layer or Phase, it isn't even 'downwards' compatible with MP3.User:195.64.95.116 02:25, 28 Apr 2005 (UTC) ==Piracy== I think there should be a heading regarding the allegations of "piracy" and the RIAA lawsuits. perhaps mention of the mp3/warez "trading" scene? Does anyone agree? User:Alkivar 04:56, 19 Oct 2004 (UTC) :VERY much agreed. User:Afolkman 1:41, 16 Nov 2004 ==Summary and Psychoacoustics== There are two things that I don't like about this page: * I think the one-line summary on the very top of the page should give more information -- one has to trawl way down the page before psychoacoustics are mentioned * The History section contains useful information, but I think there's too much babble about claimed or presumably more correct bitrates. That part should move to the Quality section. I've changed the link to psychoacoustics from Pycho-acoustic coding to Psychoacoustics as there is a redirect. --User:Cpk 21:20, 4 Sep 2004 (UTC) ==Legality and Acceptance== From the 2nd to last paragraph: "Of course, until there is widespread acceptance, nobody will bother with litigation and without a clear-cut status, there is unlikely to be wide-spread acceptance." I disagree with this bit entirely. Smoking marijuana and downloading copyrighted mp3s both have a clearcut legal status--that is, illegal--in many countries but both activities enjoy "wide-spread acceptance." So "of course" the sentence oversteps the mark quite a bit. Furthermore, the sentence preceding it: "I know of no rigorous listening tests to back up the quality claims and the IP questions have not been litigated, so nobody really knows for show what the status is." is from a point-of-view which the wikipedia does not maintain, that is, first-person, and makes another inaccurate claim, which is that no one knows the legal status--activities are legal until litigated otherwise. I'm moving the two sentences here. : ''(redacted from the paragraph beginning "The Vorbis format")'' : "I know of no rigorous listening tests to back up the quality claims and the IP questions have not been litigated, so nobody really knows for show what the status is. Of course, until there is widespread acceptance, nobody will bother with litigation and without a clear-cut status, there is unlikely to be wide-spread acceptance." --KQ ==Numbers, Parts and Layers== MP3 refers to :MPEG-1 Layer 3. MP2 (audio files) refer to :MPEG-2 Layer 3. AFAIK, MPEG-2 Layer 3 is basically the same as MPEG-1 Layer 3, with some slightly different packetization. Is it worth even putting it in the list of similar formats? AAC is also known as MPEG-2 AAC, but this probably isn't worth worrying about. -D MP3 actually refers to all MPEG layer 3 audio. MP3 at sampling frequency at least 32 KHz is called MPEG-1 layer 3 and uses MPEG-1 packets; MP3 at sampling frequency up to 24 KHz is called MPEG-2 layer 3 and uses MPEG-2 packets. ":MP2" is primarily MPEG-1 layer 2 audio used in classical MPEG applications such as :CD-i and :Video CD, but you'll often find MP3 files labeled as MP2 to get them through file type filters on web hosting services. Winamp processes all files named *.mp2 and *.mp3 as generic MPEG audio, sending them to its "Nitrane" MPEG audio decoder. See http://www.mpeg.org/MPEG/MPEG-audio-player.html --PP Argh. Looks like you're right. I'm still confused, though. According to the MPEG specs, MPEG-1 Layer 2 describes video, Layer 3 describes audio. Are there sub-layers to "Layer 3", and is that what we're talking about? I find this whole thing very messy, and it'd be nice to clean it up on the :MPEG pages. User:Dachshund :Response to User:Dachshund: Don't confuse "Parts" and "Layers". Part 2 is video. Part 3 is audio. In the case of Audio Layer 3, the term "Layer" refers to a lower level of the hierarchy than the term "Part". Layer 3 is something inside of Part 3. User:Pangolin 06:51, 12 Mar 2005 (UTC) ==Codecs and Algorithms== Hmm, I'm a bit confused. 'codec' is said to be the _same_ as an audio compression algorithm. I would think a codec is a specific _implementation_ of an audio compression algorithm. Am i just plain wrong? or? --User:arcade : Yes, in my opinion, codec (''co''der + ''de''coder, analagous to modem being short for ''mo''dulator + ''dem''odulator) is something completely different than an algorithm. While an algorithm could be said to be a set of instructions to yield a desired result, a codec is an ''implementation'' of both an algorithm and also the reverse of the same algorithm, to aid media creation and conversion tools. In other words, I think they're two completely different things. I'll fix this problem in the description. Even the article page for Codec that this one links to, says that a codec is a device or program processing the data in some way. I.e. not an algorithm, which is only a set of instructions on how to process the data. --User:Jugalator :It's even more complex a picture than that. In this case, the standard specifies only the ''decoder'', and says very little about the ''encoder''. So the standard does not specify a ''codec'', only part of one. The algorithm used for encoding is not specified. But, properly, the term algorithm is a general term that can also apply to the specified decoding process by itself. User:Pangolin 06:51, 12 Mar 2005 (UTC) == NPOV complaints == This article reads like it was written by an audiophile. Choice excerpts: *To many other listeners, 128 kbit/s is unacceptably low quality, which is unfortunate since many commonly-available encoders set this as their default bitrate. *It is important to know that despite of all the flaws, recent multiformat listening tests (http://www.rjamorim.com/test/multiformat128/results.html) once again show that LAME MP3 easily rivals its technological successor AAC. (Vorbis aoTuV is tied with Musepack at first place, Lame MP3 is tied with iTunes AAC at second place, WMA Standard is in third place and Atrac3 gets last place). (bold original) Most of the stuff under the encoder comparison is also POVish. The Alternatives is similar. Random speculation has worked its way in. Finally, the Online Music Resources is marginal. - User:Fennec User_Talk:Fennec 03:34, 10 Jul 2004 (UTC) What part of that "despite of all the flaws" did you find 'audiophile'-ish? You can't disregard the fact that inherent to this format (MP3) there are quality-issues involved. Everybody wants (and needs) to know that, in order to understand what MP3 is about. So, to then state under some Quality-section that MP3 is some kind of ugly sounding bad quality trashy format, seems very unfair to me. Check these if you are not convinced; http://www.heise.de/ct/00/06/092/ (I believe there is a translated version of it somewhere) http://jthz.com/mp3/#MYTH So, that is why I posted the bold part; use the right encoder, with the right config, and you'll have flawless quality MP3 encoding. It's been proven. User:195.64.95.116 01:30, 5 Sep 2004 (UTC) I agree, this does read like it was written by an audiophile. Feel free to edit if you don't like it. == MP3: Now with NPOV == The old article was full of awful propaganda, so I revamped it and moved some things into the LAME article. User:DG User_talk:DG 10:44, 4 Sep 2004 (UTC) I kinda disagree with you on that. As with Winamp, also LAME is very much to blame for the grand success of the format. Let's not forget that this was one of the first and highest quality FREE MP3 encoders out there (next to Blade), whilst others needed payment or licensing before being used. So, when speaking of MP3, one needs to speak of LAME. The one would never be this popular without the other. I would hardly call that propaganda, or POV, it's simple fact. User:195.64.95.116 01:21, 5 Sep 2004 (UTC) :I'm not sure what you're proposing is a "proven scientific fact." There's no such thing as a proven scientific fact. Anyway, anything is "up for discussion." You simply can't make an edit and declare that it is unquestionable. I believe you are saying that it's a "scientific fact" that nobody can detect the difference between 256kbps MP3 and an uncompressed source. That is untrue, although almost nobody can tell the difference, some golden ears listeners can on certain samples. If you're going to insert these statements you should back them up. You cannot just say "numerous listening tests." :I deleted the paragraph from the design limitations section, because this is already discussed in the MP3 quality section. Please clarify it there if you want. User:Rhobite 23:01, Oct 3, 2004 (UTC) It is proven scientific fact that 1 added to 1 makes 2. If you can't get that, you're not worth my time, and I'm not going to discuss proven facts concerning our hearing or MP3 quality, I have better things to do. If you want to state silly 'claims' on MP3 quality which have no base whatsoever other than gossipy (trying to sound like an expert) speak, I'm going against that. I would refer to rec.audio.pro and being a member of the Audio Engineering Society. The point where experts, the high-end listeners and the likes, will not be able to distinguish the MP3 file from the original currently lies around 180 kbps VBR, and 224 kbps CBR mp3 files. This is where 50% of them will say that the mp3 is the original and/or vice versa, i.e. where they can't tell the difference. (This is researched on using LAME.)User:195.64.95.116 18:53, 4 Oct 2004 (UTC) :Can you link to a study, other than that German study from 4 years ago? Can you link to any specific posts on rec.audio.pro? ::You can all test it yourselves, this is quite easy to do. If you can't understand that, you don't belong in this discussion anyway. It's like discussing existence of gravity, or the magnetic polar fields. They are there, and you can't babble on about it the way you want to. Furthermore, the articles in rec.audio.pro or elsewhere would not be read or understood by you anyway. User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :The burden is on you. If you refuse to discuss your edits or link to any studies, you are not "worth my time" either. Please do not curse in your edit summaries, and do not personally attack me. ::I do as I see fit thank you very much. You must have been deserving of me personally attacking you. User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :MP3 and CDDA are not directly comparable. I will not defer to your self-proclaimed "authority." ::Of course they are; they are both the end-medium formats people listen to.User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :Also, if you insist on reverting, please don't reintroduce your own grammar and spelling errors. User:Rhobite 19:13, Oct 4, 2004 (UTC) ::If anything I've corrected yours.User:195.64.95.116 15:54, 31 Dec 2004 (UTC) It may help here to consider a fact as something that is not known to be disputed anywhere today by otherwise reasonable people. Since there is obviously some dispute here about this "fact", our WP:NPOV policy arises to meet the occasion. Perhaps it is time to "characterize the dispute" if necessary, or merely to to back off on the fact with something like, "many people even claim they cannot detect a difference between P and Q." I will watch this page for a while. Be sure you are well familiar with the contents of the WP:NPOV article. And as always, remember wikilove and have a nice day! User:Hawstom - User_talk:Hawstom 16:35, 6 Oct 2004 (UTC) any criticisms toward the technology would be personal points of view made by the users of mp3's. :This makes no sense. Quality of audio-reproduction can be measured. If this wasn't the case, something like MP3 wouldn't exist, nor would it sound as good as it does these days.User:195.64.95.116 15:54, 31 Dec 2004 (UTC) as they are based on the opinions of persons they should not be included in the article. instead try adding links to reveiws made by some sort of professional organization and let reader form their own opinions instead of trying to guide their opinions with your own through the artical--User:Larsie 21:40, 19 Oct 2004 (UTC) ==Compression scheme vs. encoding scheme== CDDA does not compress audio. It is uncompressed 44.1 kHz, 16-bit stereo audio. CDDA is merely a format for encoding this audio along with error correction. MP3, on the other hand, is a compression format which can compress many sample rates and sizes, including 44.1/16/stereo, as well as a wide range of other combinations. Such as 22 kHz, 48 kHz, and even 96 kHz. Because of this, CDDA and MP3 are not directly comparable. You simply CANNOT say that one is better than the other, it's apples and oranges. User:Rhobite 21:42, Oct 27, 2004 (UTC) :Agreed, you cannot simply say that one is "better" than the other. But this is not because CDDA does "encoding" while MP3 does something completely different called "compression", but because the domain of MP3 is much greater than that of CDDA. Both are formats for storing PCM digital audio, and from the experience of the average computer user, both are ''overwhelmingly'' used for nothing except 44.1/16/stereo. For such an appropriately restricted application, they are perfectly comparable. One might say "using equipment XYZ and audio samples PQR, 50% of sample of 100 untrained listeners considered MP3 (using encoder MNO with settings JKL and bitrate ABC) to be not noticably worse than its CDDA source", and this would be a perfectly valid, reproducible test. User:Smyth">User:Smyth|– User:Smyth 11:53, 30 Oct 2004 (UTC) ::Fact remains that one can encode to MP3 from a much higher (high-end) quality audio source than the "box" where CDDA needs to fit in. For CDDA one would need to bring quality down, where samplerate, dynamics and bit-depth are concerned. This is not related to "tests" or opinions, this is sheer reality. CDDA has limitations as well, and they can actually be regarded as more important (reproduction-quality wise) than those of MP3. All this as long as it concerns playback quality and nothing more. User:195.64.95.116 16:24, 31 Dec 2004 (UTC) == Sampling rate == The text refers to "available sample frequencies." Would it be possible to define what "sample frequences" or "sample rate" means? :Sampling frequency? User:Smyth">User:Smyth|– User:Smyth 01:46, 8 Nov 2004 (UTC) == Value judgments == Wikipedia articles don't make value judgments or recommendations, such as recommending that non-professionals never have a reason to use lossless compression. In any case, this statement is not true: "Those who will only listen, do not need to use lossless compression, since they won't hear the difference with MP3." You can't make blanket statements like that, some people can indeed tell MP3 - even with a good compressor - from audio that has never been compressed. :They can up to a measured degree. This can be proven and it often has been. Beyond certain high enough bitrates NO HUMAN will be capable of telling the difference.User:195.64.95.116 16:16, 31 Dec 2004 (UTC) Etree and archive.org distribute lossless copies of nearly every show - there is obviously a large group of listeners who feels MP3 is inadequate for their uses. User:Rhobite 23:06, Nov 15, 2004 (UTC) :The fact that MP3 is now often considered a degraded format, surpassed by other formats, has nothing to do with that. It's simply because
:1) there are bad mp3 encoders around (lots of them in fact)
:2) MP3 tends to need some type of special treatment beforehand to reach optimum quality, other formats don't.
:3) MP3 is being used the wrong way a lot, cascaded, with low quality encoding, within mastering mix-CD's and so on.
:I mention the obvious importance in the different ways of use for audio(files), since THAT is the main reason people start to think MP3 is a bad quality format; They use it to re-encode, they start to use it as a professional format, they end up mastering CD's from MP3 files. Of course they shouldn't, MP3 is intended as a final "play and listen" format only, not to be processed further on in any way or form possible. CDDA and MP3 are almost the same in that regard.User:195.64.95.116 16:16, 31 Dec 2004 (UTC) ==Possible Plagiarism== I just searched for info about the use of Tom's Diner in early MP3 work and I found this page: [http://www.secretmaker.com/technopedia/m/mp3/default.html]. Does anyone know what's what? :It looks like this page is a possible Wiki clone? Several pages seem similar to Wiki and it calls itself "Technopedia". 08:16, 14 Feb 2005 (UTC) ::It is a wikipedia clone site. This is explicitly allowed by the GFDL, but they do have to credit the original authors and provide access to the source of the article, which they're not doing. I've listed them on the Mirrors and Forks page at Wikipedia:Mirrors_and_forks/Stu#Secretmaker, as a low compliance site. Thanks for pointing this out. User:Rhobite 08:31, Feb 14, 2005 (UTC) == Incorrect Statement of The Law== I believe this statement: '' However, non-commercial use and distribution of any item, with software codecs included, is by definition free of any relevance or impediments under patent law. '' Is legally incorrect. For example, there is no U.S. law provision allowing for "fair use" of patents, in the sense that any noncommercial or ''de minimis'' use is not an exception for infringement. See 35 USC 271. The only exception to partent infringement that I know of is experimentation to validate that the patent is operative. Perhaps the author was referring to "fair use" in a copyright sense. If so, that makes sense as 17 USC 107 "Limitations on exclusive rights: Fair Use" would apply. As the topic referenced in the article is patents I deleted the sentence. I note that it is unlikely the patent holder would sue an individual who was making non commercial use of the patent, but in theory I think the indivudual has no legal defense due to the noncommercial nature of the use. Would be interesting how this would play out in other countries. == Online music resources == This section seems a non sequitur -- for example, Apple's music store does not use the MP3 format at all. == Patents and details == What parts, exactly, of the algorithm are patented? Also, time-to-frequency conversion and physcoacoustics have much prior art. Should this be inclueded? And we also need to include a description of the algorithm. User:Watsonladd 19:09, Apr 25, 2005 (UTC) == patent == When does the patent expire in the US and other countries?
#REDIRECT MP3
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MP3
MP3 is a popular digital audio encoding and lossy data compression audio compression format. It was designed to greatly reduce the amount of data (10:1 compression is common) required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. In popular usage, MP3 also refers to files of sound or music recordings stored in the MP3 format on computers. The name is derived from "MPEG-1 Audio Layer 3", more formally known as "MPEG-1 Part 3 Layer 3" or "International Organization for Standardization/International Electrotechnical Commission 11172-3 Layer 3". Reportedly, the ".mp3" filename extension is also sometimes used on audio files encoded using the newer "MPEG-2 Audio Layer 3" standard (a.k.a. "MPEG-2 Part 3 Layer 3" or "International Organization for Standardization/International Electrotechnical Commission 13818-3 Layer 3"). == Overview == MP3 is a lossy data compression format. It provides a representation of pulse-code modulation-encoded (PCM) audio data in a much smaller size by discarding portions that are considered "less important" to human hearing. (This is similar in concept to JPEG lossy compression for images.) A number of techniques are employed in MP3 to determine what portions of the audio can be discarded, including psychoacoustics. MP3 audio can be compressed with different bit rates, providing a range of tradeoffs between data size and sound quality. MP3 Surround, a version of the format supporting 5.1 channels, was introduced in December 2004. MP3 Surround is backward compatible with standard stereo MP3, and file sizes are similar. The MP3 format uses, at its heart, a hybrid transform to transform a time domain signal into a frequency domain signal: * 32 band polyphase quadrature filter * 36 or 12 tap MDCT, size can be selected independent for subband 0...1 and 2...31 * aliasing reduction postprocessing In terms of the MPEG specifications, Advanced audio coding (AAC) from MPEG-4 is to be the successor of the MP3 format, although there has been a significant movement to create and popularize other audio formats. Nevertheless, any 'succession' is not likely to happen for a significant amount of time due to MP3's overwhelming popularity. MP3 enjoys extremely wide popularity and support, not just by end-users and software but by hardware such as DVD and CD players. ==History== ===Development=== MPEG-1 Audio Layer 2 encoding started life as the Digital Audio Broadcast (DAB) project initiated by the Fraunhofer Society. This project was financed by the European Union as a part of the EUREKA research program where it was commonly known as EU-147. EU-147 ran from 1987 to 1994. In 1991, there were two proposals available: Musicam (known as Layer II) and ASPEC (Adaptive Spectral Perceptual Entropy Coding) with similarities to MP3. Musicam was chosen due to its simplicity and error robustness. A working group around Karlheinz Brandenburg and Jürgen Herre took ideas from Musicam and ASPEC, added some of their own ideas and created MP3, which was designed to achieve the same quality at 128 kbit/s as MP2 at 192 kbit/s. Both algorithms were finalized in 1992 as part of MPEG-1, the first standard suite by MPEG, which resulted in the international standard International Organization for Standardization/International Electrotechnical Commission 11172-3, published in 1993. Further work on MPEG audio was finalized in 1994 as part of the second suite of MPEG standards, MPEG-2, more formally known as international standard International Organization for Standardization/International Electrotechnical Commission 13818-3, originally published in 1995. Compression efficiency of lossy compression encoders is typically defined by the bit rate because compression rate depends on bit depth and sampling rate of the input signal. Nevertheless, there are often published compression rates which use the compact disc parameters as references (44.1 kHz, 2 channels at 16 bits per channel or 2x16 bit). Sometimes the Digital Audio Tape (DAT) SP parameters are used (48 kHz, 2x16 bit). Compression ratios for this reference is higher, which demonstrates the problem of the term "compression ratio" for lossy encoders. Karlheinz Brandenburg used a CD recording of Suzanne Vega's song "Tom's Diner" as his model for the MP3 compression algorithm. This song was chosen because of its softness and simplicity, making it easier to hear imperfections in the compression format during playbacks. === MP3 went public === On the 7th July 1994 the Fraunhofer Society released the first software MP3 encoder called l3enc. With the first realtime software MP3 player Winplay3 (released 9th September 1995) people were able to encode and playback MP3 files on a PC. Because of the relative small harddrives back in that time (usually about 512 MB) the technology was essential to store music for listening pleasure on a computer. === MP2 and MP3 and the Internet === In October 1993, MP2 ("MPEG-1 Audio Layer 2") files appeared on the Internet and were often played back using "Xing MPEG Audio Player", and later in a program for Unix by Tobias Bading called MAPlay initially released on February 22, 1994. (MAPlay was also ported to Microsoft Windows.) Initially the only encoder available for MP2 production was the Xing Encoder, accompanied by the program CDDA2WAV, a CD ripper that copied CD audio to hard disks. Internet Underground Music Archive (IUMA) is generally recognized as the start of the on-line music revolution. IUMA was the Internet's first high-fidelity music web site, hosting thousands of authorized MP2 recordings before MP3 or the web were popularized. IUMA was started by Rob Lord (who later headed pioneering Nullsoft) and Jeff Patterson, both from University of California, Santa Cruz, in 1993. Other founding members include Jon Luini, Brandee Selck and Ahin Savara. In the first half of 1995, MP3 files began flourishing on the Internet. Its popularity was mostly due to, and interchangeable with, the successes of companies and software packages like Nullsoft's Winamp, mpg123 and (now Roxio-owned) Napster. Those programs made it very easy to playback, create, share and collect MP3s for the average PC users. Controversies regarding peer to peer file sharing of MP3 files have flourished in recent years — largely because high compression enables sharing of files that would otherwise be too large and cumbersome to share. Due the vastly increased spread of MP3s through the internet some major record labels reacted by filing a Napster#Legal_challenges. Since 2003, the number of MP3 blogs has exploded, while largely avoiding a backlash from record companies. Commercial online music distribution services (like ITunes Music Store) usually prefer other music file formats that support DRM to control and restrict the use of digital music. ==Quality of MP3 audio== Many listeners accept the MP3 bitrate of 128 kilobit per second (kbit/s) as near enough to compact disc quality for them. This provides a compression ratio of approximately 11:1, although listening tests show that with a bit of practice, many listeners can reliably distinguish 128 kbit/s MP3s from CD originals. To some listeners, 128 kbit/s is unacceptably low quality. Even though differences may be perceptible, this is acceptable for some listeners in some listening environments, such as a noisy car or train. Fraunhofer Gesellschaft (abbreviated FhG) publish on their official webpage the following compression ratios and data rates for MPEG-1 Layer 1, 2 and 3, intended for comparison: * Layer 1: 384 Kilobit per second, compression 4:1 * Layer 2: 192...256 kbit/s, compression 6:1...8:1 * Layer 3: 112...128 kbit/s, compression 10:1...12:1 These values are probably overly optimistic (they are likely to be influenced by public relations) because the quality depends not only on the encoding file format, but also on the quality of the psychoacoustic algorithms used by the encoder. Typical layer 1 encoders use simple psycho acoustics which result in a higher needed bit rate for Transparency (data compression) encoding. * Layer 1 encoding at 384 kbit/s, even with these simple psychoacoustics, is better than Layer 2 at 192...256 kbit/s * Layer 3 encoding at 112...128 kbit/s is worse than Layer 2 at 192...256 kbit/s. That is to say, the assumed bit rates are not equivalent in quality and the qualities are not necessarily optimal (it is generally agreed that 112 to 128 kbit/s Layer 3 is not excellent sound) and therefore the comparison is probably not reliable as an objective source. More realistic bit rates are: * Layer 1: excellent at 384 kbit/s * Layer 2: excellent at 256...384 kbit/s, very good at 224...256 kbit/s, good at 192...224 kbit/s * Layer 3: excellent at 224...320 kbit/s, very good at 192...224 kbit/s, good at 128...192 kbit/s Comparing a new file format typically is done by comparing a medium quality encoder of the old format and a highly tuned encoder of the new format. A few possible encoders: * LAME first created by Mike Cheng in early 1998, it is a (by contrast to others) fully LGPL'd MP3 encoder, with excellent speed and quality, rivaling even MP3's technological successors. * Fraunhofer Gesellschaft: Some encoders are good, some have bugs. Some early encoders are not widely used any more: ISO dist10 reference code, Xing, BladeEnc, and ACM Producer Pro. The quality of MP3 files depend on the quality of the encoder and the difficulty of the signal which must be encoded. *Good encoders produce acceptable quality at 128 to 160 kbit/s and near-Transparency (data compression) at 160 to 192 kbit/s. *Low quality encoders may never reach transparency, not even at 320 kbit/s. So it is pointless to speak of 128 kbit/s or 192 kbit/s quality, except in the context of a particular encoder or of the best available coders. A 128 kbit/s MP3 produced by a good encoder might sound better than a 192 kbit/s MP3 file produced by a bad encoder. Additionally, it is important to note that this is subjective. A given bitrate suffices for some listeners but not for others. The numbers given above are rough guidelines that work for many people, but in the field of lossy audio compression, the only true measure of the quality of a compression process is to listen to the results. An important feature of MP3 is that it is lossy — meaning that it removes information from the input in order to save space (and bandwidth cost in transferred). As with most modern lossy encoders, MP3 algorithms work hard to ensure that the parts it removes cannot be detected by human listeners by modeling characteristics of human hearing (i.e., noise masking). The importance of this is that it can gain huge savings in storage space with reasonable and acceptable (although detectable) losses in fidelity. If your aim is to archive sound files with no loss of quality (or work on the sound files in a studio) you should consider lossless data compression such as: *FLAC (FLAC) *Monkey's Audio (APE) *Shorten (SHN) *Lossless Predictive Audio Compression (LPAC) *Wavpack (WV) *TTA (TTA) *Apple Lossless These are capable of compressing 16-bit PCM audio to 38 to 80% of its original size (depending upon the characteristics of the audio itself), leaving the audio bit-for-bit identical to the original (ergo "lossless"). It is important to understand the difference between audio for further processing and audio use only for playback. Lossless formats are strongly preferred for material which will be edited, mixed, or otherwise processed because the perceptual assumptions made by lossy coders may not hold true after processing. Most people find lossy coders acceptable for audio which will only be played. Nevertheless, individual acoustic perception may vary so it is not evident that a certain psychoacoustic model can give satisfactory results for everyone. Merely changing the conditions of listening, such as the audio playing system or environment, can expose unwanted distortions caused by lossy compression. Lossless formats will produce the best possible result, at the expense of a lower compression ratio. If MP3 audio needs to be decoded and re-encoded another time, for example when it will be aired on radio, cascading lossy compression stages can significantly reduce the quality of the end-result. To prevent this, keep audio data in its original state if further operating on it is necessary. If any operation needs to be done on MP3 data, such as cutting or merging audio, or lowering bitrate, it is preferable to use software that works directly with the encoded data (such as mp3DirectCut and MP3Gain) and prevent extra decoding-encoding steps. ==Bit rate== The bit rate is variable for MP3 files. The general rule is that the higher the bitrate, the more information is included from the original sound file, and thus the higher the quality of played back audio. In the early days of MP3 encoding, a fixed bit rate was used for the entire file. Bit rates available in MPEG-1 layer 3 are 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256 and 320 kibit/s, and the available sample frequencies are 32, 44.1 and 48 kHz. 44.1 kHz is almost always used (coincides with the sampling rate of compact discs), and 128 kbit has become the de facto "good enough" standard, although 192 kbit is becoming increasingly popular on peer-to-peer file sharing programs. MPEG-2 and (the non-official) MPEG-2.5 adds more bitrates: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 kbit/s. As already mentioned, variable bit rates (VBR) are also possible. Audio in MP3 files are divided into frames (which have their own bit rate) so it is possible to change the bit rate dynamically as the file is encoded. This was not originally done, but VBR is in extensive use today. This technique makes it possible to use more bits for parts of the sound with high dynamics (much "sound movement") and fewer bits for parts with low dynamics, increasing quality and decreasing storage space further. This method compares to a sound activated tape recorder which saves the tape space from when silence was prevalent for the times when sound is being heard. Some encoders utilize this technique to a great extent. ==Design limitations of MP3== There are several limitations inherent to the MP3 format that cannot be overcome by using a better encoder. More recent audio-compression formats such as Vorbis, advanced audio coding, Musepack and WMA no longer have these limitations. In technical terms, MP3 is limited in the following ways: * In constant bitrates, bitrates are limited to a maximum of 320 kbit/s * Time resolution can be too low for highly transient signals * Encoder/decoder overall delay is not defined * No scaleband factor for frequencies above 15.5/15.8 kHz * Joint stereo is done on a frame-to-frame basis Nevertheless a well-tuned MP3 encoder can perform competitively even with these restrictions. ==Encoding of MP3 audio== The MPEG-1 standard does not include a precise specification for an MP3 encoder. The decoding algorithm and file format, as a contrast, are well defined. Implementors of the standard were supposed to devise their own algorithms suitable for removing parts of the information in the raw audio (or rather its Modified discrete cosine transform representation in the frequency domain). This is the domain of psychoacoustics, which aims at understanding how human acoustical perception works (both in our ears and in our brain). As a result, there are many different MP3 encoders available, each producing files of differing quality. Comparisons are widely available, so it is easy for a prospective user of an encoder to research the best choice. It must be kept in mind that an encoder that is proficient at encoding at higher bitrates (such as LAME, which is in widespread use for encoding at higher bitrates) is not necessarily as good at other, lower bitrates. ==Decoding of MP3 audio== Decoding, on the other hand, is carefully defined in the standard. Most decoders are "bitstream compliance", meaning that the uncompressed output they produce from a given MP3 file will be the same (within a specified degree of rounding tolerance) as the output specified mathematically in the standard document. Therefore, for the most part, comparison of decoders is almost exclusively based on how computationally efficient they are (i.e., how much computer memory or CPU time they use in the decoding process). ==ID3 and other tags== :''See main articles ID3 and APEv2 tag'' A "tag" is data stored in an MP3 (as well as other formats) which contains metadata such as the title, artist, album, track number or other information about the MP3 file to be added to the file itself. The most widespread standard tag formats are currently the ID3 ID3v1 and ID3v2 tags, and the more recent APEv2 tag. APEv2 was originally developed for the MPC (audio compression format) (see [http://www.personal.uni-jena.de/~pfk/mpp/sv8/apetag.html the APEv2 specification]). APEv2 can coexist with ID3 tags in the same file, but it can also be used by itself. ==Volume normalization== As compact discs and other various sources are recorded and mastered at different volumes, it is useful to store volume information about a file in the tag so that at playback time, the volume can be dynamically adjusted. A few standards for encoding the gain of an MP3 file have been proposed. The idea is to normalize the volume (not the volume ''peaks'') of audio files, so that the volume does not change between consecutive tracks. The most popular and widely-used solution for storing replay gain is known simply as "Replay Gain". Typically, the average volume and clipping information about an audio track is stored in the metadata tag. ==Alternative technologies== Many other lossy audio codecs exist, including: * MP2 (format) (MP2), MP3's predecessor; * Ogg Vorbis from the Xiph.org Foundation, a free software and patent free codec. * MPC (audio compression format), also known as Musepack (formerly MP+), a derivative of MP2; * mp3PRO from Thomson Multimedia combining MP3 with Spectral Band Replication; * AC-3, used in Dolby Digital and DVD; * ATRAC, used in Sony's Minidisc; * MPEG-4 Advanced audio coding, used by Apple Computer's iTunes Music Store and iPod * Windows Media Audio (WMA) from Microsoft. * QDesign, used in QuickTime at low bitrates; * AMR-WBplus Enhanced Adaptive Multi Rate WideBand codec, optimized for cellular and other limited bandwidth use; * RealAudio from RealNetworks, frequently in use for streaming on websites; * Speex, free software and patent free codec based on CELP specifically designed for speech and VoIP. mp3PRO, MP3, AAC, and MP2 are all members of the same technological family and depend on roughly similar psychoacoustic models. The Fraunhofer Gesellschaft owns many of the basic patents underlying these codecs, with Dolby Labs, Sony, Thomson Consumer Electronics, and ATT holding other key patents. There are also some non-lossy (lossless data compression) audio compression methods used on the Internet. While they are not similar to MP3, they are good examples of other compression schemes available. These include: * FLAC stands for 'Free Lossless Audio Codec' * Monkey's Audio * SHN, also known as Shorten * TTA * Wavpack Listening tests [http://www.rjamorim.com/test/] have attempted to find the best-quality lossy audio codecs at certain bitrates. The tests have suggested that for some audio samples, newer audio codecs including Ogg Vorbis, mp3PRO, AC-3, Windows Media Audio, MPC and RealAudio perform better than MP3. Generally, these codecs achieve the equivalent of MP3 128kbps at around 80kbps. At 128kbps, Ogg Vorbis and MPC performed marginally better than other codecs. At 64kbps, ACC and mp3pro performed marginally better than other codecs. At high bitrates (128kbps+), most people do not hear significant differences. What is considered 'CD quality' is quite subjective; for some 128kbps MP3 is sufficient, while for others 192kbps MP3 is necessary. Though proponents of newer codecs such as WMA and RealAudio have asserted that their respective algorithms can achieve CD quality at 64 kbit/s, listening tests have shown otherwise; however, the quality of these codecs at 64 kbit/s is definitely superior to MP3 at the same bandwidth. The developers of the patent-free Ogg Vorbis codec claim that their algorithm surpasses MP3, RealAudio and WMA sound quality, and the listening tests mentioned above support that claim. Thomson claims that its mp3PRO codec achieves CD quality at 64 kbit/s, but listeners have reported that a 64 kbit/s mp3PRO file compares in quality to a 112 kbit/s MP3 file and does not come reasonably close to CD quality until about 80 kbit/s. MP3, which was designed and tuned for use alongside MPEG-1/2 Video, generally performs poorly on monaural data at less than 48 kbit/s or in stereo at less than 80 kbit/s. ==Licensing and patent issues== Thomson SA controls licensing of the [http://www.mp3licensing.com/patents/index.html MPEG-1/2 Layer 3 patents] in countries such as the United States and Japan that recognize software patents. Thomson has decided to attempt to collect royalties for the patents. In September 1998, the Fraunhofer Institute sent a letter to several developers of MP3 software stating that a license was required to "distribute and/or sell decoders and/or encoders". The letter claimed that unlicensed products "infringe the patent rights of Fraunhofer and THOMSON. To make, sell and/or distribute products using the [MPEG Layer-3] standard and thus our patents, you need to obtain a license under these patents from us." These patent issues significantly slowed the development of unlicensed MP3 software and led to increased focus on creating and popularising alternatives such as WMA and Ogg Vorbis. Microsoft, the makers of the Windows operating system, chose to move away from MP3 to their own proprietary Windows Media formats to avoid the licensing issues associated with the patents. Until the key patents expire, open source / free software encoders and players appear to be illegal for commercial use in countries that recognize software patents. For information about licensing fees see [http://www.mp3licensing.com/help/developer.html] and [http://www.mp3licensing.com/royalty/index.html]. In spite of the patent restrictions, the perpetuation of the MP3 format continues; the reasons for this appear to be the network effects caused by: * familiarity with the format, not knowing alternatives exist, * the large quantity of music now available in the MP3 format, * the wide variety of existing software and hardware that takes advantage of the file format that revolutionized the music industry and copyright law. == Online music resources == Tools such as iRate try to make it easier to find music that matches the listener's tastes. There are several online music stores. Apple's iTunes Music Store store is presently the most popular commercial online music offering. Independent artists are able to use smaller sites to provide distribution. A controversial MP3 portal is the Russian site AllOfMP3.com, which offers downloads of thousands of albums and video clips by mainstream artists, priced at $20 per gigabyte. There are also several online columnists who edit news sites focused on digital music and the grassroots community it spawned. They include Richard Menta's [http://www.mp3newswire.net MP3newswire.net], an early MP3 news site started in 1998, Jon Newton's [http://www.p2pnet.net P2Pnet], and Thomas Mennecke's [http://www.slyck.com Slyck.com]. Other sites like Download.com and Vitaminic.com which allow artists to choose to post their own music for free download. ==See also== *ID3 *Digital audio player *Media player *Software patent ==External links== * [http://www.iis.fraunhofer.de/amm/techinf/layer3/ Fraunhofer IIS] * [http://www.mp3licensing.com/patents/index.html List of relevant patents] * [http://mpgedit.org/mpgedit/mpeg_format/MP3Format.html MP3 File Format Specification] * [http://www.tnt.uni-hannover.de/project/mpeg/audio/ MPEG Audio Web Page] * [http://www.tnt.uni-hannover.de/project/mpeg/audio/faq/ MPEG Audio FAQ] * [http://mp3.ithaki.net/ MP3 Search Engine - Finds MP3 files] * [http://www.id3.org/ ID3v2 Information] * [http://www.mp3-news.net/ News about the MP3 format] * [http://www.mp3licensing.com Thomson's mp3licensing.com] * [http://www.xiph.org/ogg/vorbis/listen.html Xiph.org listening test] - Vorbis vs. MP3, RealAudio, Windows Media, etc. * [http://www.rjamorim.com/test/ Roberto's public listening tests] - blind, controlled listening tests of lossy compression formats including MP3. * [http://www.codingtechnologies.com/ Coding Technologies (DAB related)] * [http://www.factum.se/ Factum Electronics (DAB related)] * [http://www.mp3-tech.org/content/?Mp3%20Limitations Mp3 Limitations] - LAME developer explains flaws and restricitons of MP3 compared to newer formats ===Software links=== * [http://mitiok.ma.cx/ LAME MP3 Encoder downloads] * [http://www.rarewares.org/mp3.html Rarewares MP3 software downloads] * [http://www.mpesch3.de/ mp3DirectCut, for fast mpeg audio editing] * [http://mp3gain.sourceforge.net/ MP3Gain, changes audio-level of mp3 files] * [http://www.mpeg.org/MPEG/audio.html MPEG Audio Resources and Software] * [http://mplib.sourceforge.net/ mp3 tagging library (software)] * [http://www.id3-tagit.de ID3 tag + filename manipulation software] (ID3 is the tagging system used to store information about tracks in the MP3 files) Audio codecs Digital audio Digital Revolution Digital media Computer file formats
MP3
==MPEG-I/II== In the first line it says "MPEG-1/2", and this needs to be explained on the page, I think. Here's what I know about it: Phase 1 can handle input streams (or WAV files) with a sample frequency of 48000, 44100 or 32000 Hz and is therefore used most often, obviously. Phase 2 will only support stream for 24000, 22050 and 16000 Hz. Basically, Phase 2 is intended for lower bit rates (e.g. for voice communication, or if you need small files with reduced quality, podcasts and live online audio-feeds and the likes). The lowest bit-rate for Phase 2 is 8 kBits/sec while for Phase 1 the lowest bit rate is 32 kBits/s. User:195.64.95.116 23:11, 11 Mar 2005 (UTC) :Response to User:195.64.95.116: There are several problems in the above comments. Please refer to an authoritative source such as [http://www.chiariglione.org/mpeg/ The official MPEG site] or [http://www.mpegif.org The MPEG Industry Forum site] or perhaps the somewhat less official [http://www.mpeg.org MPEG.ORG site]. Be very careful to only get your information from such reliable sources, as there is a significant amount of confusion found on more random web sites. Do not call the MPEG-X numerical suffixes "Phases". Do not use roman numerals to denote them. MP3 originated from MPEG-1 Audio Layer 3, also properly referred to as MPEG-1 Part 3 Layer 3 (where "Part 3" refers to audio coding, "Part 1" is multiplexing, "Part 2" is video coding, etc.). The stuff above about sample frequency looks wrong too. I'm not personally aware of any connection between MP3 and MPEG-2, except for the former being a predecessor of the latter. User:Pangolin 06:16, 12 Mar 2005 (UTC) ::Actually, it is exactly the other way around; You have to call the old MPEG-X Phases, since they are, and always have been. .MP2 and .MP3 used to both even be called .MPA and this was way before the Part 1 or Layer 3 issues came into play. Hey, I know, because I was there testing and using it back in the day. I don't really care what you think it should be, I know what the Phases meant, why they are there in the format, and when they started putting it in. The "Part 1" came into play because of incompatibility with Part 2, which is different from Phase 1 and Phase 2. MP3 originated from MPA, which in turn changed to MPEG Phase 1 Layer 3. To help make it clear, it was decided by its creators (hey, ask them) to use the Roman for the Layers. Furthermore, I don't know what fool put in the MPEG-2 part about 'the new' MP3, but that's a silly thing to do; That new MPEG-2 is not the same as MP2, the new MPEG-2 is no longer describing the Layer or Phase, it isn't even 'downwards' compatible with MP3.User:195.64.95.116 02:25, 28 Apr 2005 (UTC) ==Piracy== I think there should be a heading regarding the allegations of "piracy" and the RIAA lawsuits. perhaps mention of the mp3/warez "trading" scene? Does anyone agree? User:Alkivar 04:56, 19 Oct 2004 (UTC) :VERY much agreed. User:Afolkman 1:41, 16 Nov 2004 ==Summary and Psychoacoustics== There are two things that I don't like about this page: * I think the one-line summary on the very top of the page should give more information -- one has to trawl way down the page before psychoacoustics are mentioned * The History section contains useful information, but I think there's too much babble about claimed or presumably more correct bitrates. That part should move to the Quality section. I've changed the link to psychoacoustics from Pycho-acoustic coding to Psychoacoustics as there is a redirect. --User:Cpk 21:20, 4 Sep 2004 (UTC) ==Legality and Acceptance== From the 2nd to last paragraph: "Of course, until there is widespread acceptance, nobody will bother with litigation and without a clear-cut status, there is unlikely to be wide-spread acceptance." I disagree with this bit entirely. Smoking marijuana and downloading copyrighted mp3s both have a clearcut legal status--that is, illegal--in many countries but both activities enjoy "wide-spread acceptance." So "of course" the sentence oversteps the mark quite a bit. Furthermore, the sentence preceding it: "I know of no rigorous listening tests to back up the quality claims and the IP questions have not been litigated, so nobody really knows for show what the status is." is from a point-of-view which the wikipedia does not maintain, that is, first-person, and makes another inaccurate claim, which is that no one knows the legal status--activities are legal until litigated otherwise. I'm moving the two sentences here. : ''(redacted from the paragraph beginning "The Vorbis format")'' : "I know of no rigorous listening tests to back up the quality claims and the IP questions have not been litigated, so nobody really knows for show what the status is. Of course, until there is widespread acceptance, nobody will bother with litigation and without a clear-cut status, there is unlikely to be wide-spread acceptance." --KQ ==Numbers, Parts and Layers== MP3 refers to :MPEG-1 Layer 3. MP2 (audio files) refer to :MPEG-2 Layer 3. AFAIK, MPEG-2 Layer 3 is basically the same as MPEG-1 Layer 3, with some slightly different packetization. Is it worth even putting it in the list of similar formats? AAC is also known as MPEG-2 AAC, but this probably isn't worth worrying about. -D MP3 actually refers to all MPEG layer 3 audio. MP3 at sampling frequency at least 32 KHz is called MPEG-1 layer 3 and uses MPEG-1 packets; MP3 at sampling frequency up to 24 KHz is called MPEG-2 layer 3 and uses MPEG-2 packets. ":MP2" is primarily MPEG-1 layer 2 audio used in classical MPEG applications such as :CD-i and :Video CD, but you'll often find MP3 files labeled as MP2 to get them through file type filters on web hosting services. Winamp processes all files named *.mp2 and *.mp3 as generic MPEG audio, sending them to its "Nitrane" MPEG audio decoder. See http://www.mpeg.org/MPEG/MPEG-audio-player.html --PP Argh. Looks like you're right. I'm still confused, though. According to the MPEG specs, MPEG-1 Layer 2 describes video, Layer 3 describes audio. Are there sub-layers to "Layer 3", and is that what we're talking about? I find this whole thing very messy, and it'd be nice to clean it up on the :MPEG pages. User:Dachshund :Response to User:Dachshund: Don't confuse "Parts" and "Layers". Part 2 is video. Part 3 is audio. In the case of Audio Layer 3, the term "Layer" refers to a lower level of the hierarchy than the term "Part". Layer 3 is something inside of Part 3. User:Pangolin 06:51, 12 Mar 2005 (UTC) ==Codecs and Algorithms== Hmm, I'm a bit confused. 'codec' is said to be the _same_ as an audio compression algorithm. I would think a codec is a specific _implementation_ of an audio compression algorithm. Am i just plain wrong? or? --User:arcade : Yes, in my opinion, codec (''co''der + ''de''coder, analagous to modem being short for ''mo''dulator + ''dem''odulator) is something completely different than an algorithm. While an algorithm could be said to be a set of instructions to yield a desired result, a codec is an ''implementation'' of both an algorithm and also the reverse of the same algorithm, to aid media creation and conversion tools. In other words, I think they're two completely different things. I'll fix this problem in the description. Even the article page for Codec that this one links to, says that a codec is a device or program processing the data in some way. I.e. not an algorithm, which is only a set of instructions on how to process the data. --User:Jugalator :It's even more complex a picture than that. In this case, the standard specifies only the ''decoder'', and says very little about the ''encoder''. So the standard does not specify a ''codec'', only part of one. The algorithm used for encoding is not specified. But, properly, the term algorithm is a general term that can also apply to the specified decoding process by itself. User:Pangolin 06:51, 12 Mar 2005 (UTC) == NPOV complaints == This article reads like it was written by an audiophile. Choice excerpts: *To many other listeners, 128 kbit/s is unacceptably low quality, which is unfortunate since many commonly-available encoders set this as their default bitrate. *It is important to know that despite of all the flaws, recent multiformat listening tests (http://www.rjamorim.com/test/multiformat128/results.html) once again show that LAME MP3 easily rivals its technological successor AAC. (Vorbis aoTuV is tied with Musepack at first place, Lame MP3 is tied with iTunes AAC at second place, WMA Standard is in third place and Atrac3 gets last place). (bold original) Most of the stuff under the encoder comparison is also POVish. The Alternatives is similar. Random speculation has worked its way in. Finally, the Online Music Resources is marginal. - User:Fennec User_Talk:Fennec 03:34, 10 Jul 2004 (UTC) What part of that "despite of all the flaws" did you find 'audiophile'-ish? You can't disregard the fact that inherent to this format (MP3) there are quality-issues involved. Everybody wants (and needs) to know that, in order to understand what MP3 is about. So, to then state under some Quality-section that MP3 is some kind of ugly sounding bad quality trashy format, seems very unfair to me. Check these if you are not convinced; http://www.heise.de/ct/00/06/092/ (I believe there is a translated version of it somewhere) http://jthz.com/mp3/#MYTH So, that is why I posted the bold part; use the right encoder, with the right config, and you'll have flawless quality MP3 encoding. It's been proven. User:195.64.95.116 01:30, 5 Sep 2004 (UTC) I agree, this does read like it was written by an audiophile. Feel free to edit if you don't like it. == MP3: Now with NPOV == The old article was full of awful propaganda, so I revamped it and moved some things into the LAME article. User:DG User_talk:DG 10:44, 4 Sep 2004 (UTC) I kinda disagree with you on that. As with Winamp, also LAME is very much to blame for the grand success of the format. Let's not forget that this was one of the first and highest quality FREE MP3 encoders out there (next to Blade), whilst others needed payment or licensing before being used. So, when speaking of MP3, one needs to speak of LAME. The one would never be this popular without the other. I would hardly call that propaganda, or POV, it's simple fact. User:195.64.95.116 01:21, 5 Sep 2004 (UTC) :I'm not sure what you're proposing is a "proven scientific fact." There's no such thing as a proven scientific fact. Anyway, anything is "up for discussion." You simply can't make an edit and declare that it is unquestionable. I believe you are saying that it's a "scientific fact" that nobody can detect the difference between 256kbps MP3 and an uncompressed source. That is untrue, although almost nobody can tell the difference, some golden ears listeners can on certain samples. If you're going to insert these statements you should back them up. You cannot just say "numerous listening tests." :I deleted the paragraph from the design limitations section, because this is already discussed in the MP3 quality section. Please clarify it there if you want. User:Rhobite 23:01, Oct 3, 2004 (UTC) It is proven scientific fact that 1 added to 1 makes 2. If you can't get that, you're not worth my time, and I'm not going to discuss proven facts concerning our hearing or MP3 quality, I have better things to do. If you want to state silly 'claims' on MP3 quality which have no base whatsoever other than gossipy (trying to sound like an expert) speak, I'm going against that. I would refer to rec.audio.pro and being a member of the Audio Engineering Society. The point where experts, the high-end listeners and the likes, will not be able to distinguish the MP3 file from the original currently lies around 180 kbps VBR, and 224 kbps CBR mp3 files. This is where 50% of them will say that the mp3 is the original and/or vice versa, i.e. where they can't tell the difference. (This is researched on using LAME.)User:195.64.95.116 18:53, 4 Oct 2004 (UTC) :Can you link to a study, other than that German study from 4 years ago? Can you link to any specific posts on rec.audio.pro? ::You can all test it yourselves, this is quite easy to do. If you can't understand that, you don't belong in this discussion anyway. It's like discussing existence of gravity, or the magnetic polar fields. They are there, and you can't babble on about it the way you want to. Furthermore, the articles in rec.audio.pro or elsewhere would not be read or understood by you anyway. User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :The burden is on you. If you refuse to discuss your edits or link to any studies, you are not "worth my time" either. Please do not curse in your edit summaries, and do not personally attack me. ::I do as I see fit thank you very much. You must have been deserving of me personally attacking you. User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :MP3 and CDDA are not directly comparable. I will not defer to your self-proclaimed "authority." ::Of course they are; they are both the end-medium formats people listen to.User:195.64.95.116 16:04, 31 Dec 2004 (UTC) :Also, if you insist on reverting, please don't reintroduce your own grammar and spelling errors. User:Rhobite 19:13, Oct 4, 2004 (UTC) ::If anything I've corrected yours.User:195.64.95.116 15:54, 31 Dec 2004 (UTC) It may help here to consider a fact as something that is not known to be disputed anywhere today by otherwise reasonable people. Since there is obviously some dispute here about this "fact", our WP:NPOV policy arises to meet the occasion. Perhaps it is time to "characterize the dispute" if necessary, or merely to to back off on the fact with something like, "many people even claim they cannot detect a difference between P and Q." I will watch this page for a while. Be sure you are well familiar with the contents of the WP:NPOV article. And as always, remember wikilove and have a nice day! User:Hawstom - User_talk:Hawstom 16:35, 6 Oct 2004 (UTC) any criticisms toward the technology would be personal points of view made by the users of mp3's. :This makes no sense. Quality of audio-reproduction can be measured. If this wasn't the case, something like MP3 wouldn't exist, nor would it sound as good as it does these days.User:195.64.95.116 15:54, 31 Dec 2004 (UTC) as they are based on the opinions of persons they should not be included in the article. instead try adding links to reveiws made by some sort of professional organization and let reader form their own opinions instead of trying to guide their opinions with your own through the artical--User:Larsie 21:40, 19 Oct 2004 (UTC) ==Compression scheme vs. encoding scheme== CDDA does not compress audio. It is uncompressed 44.1 kHz, 16-bit stereo audio. CDDA is merely a format for encoding this audio along with error correction. MP3, on the other hand, is a compression format which can compress many sample rates and sizes, including 44.1/16/stereo, as well as a wide range of other combinations. Such as 22 kHz, 48 kHz, and even 96 kHz. Because of this, CDDA and MP3 are not directly comparable. You simply CANNOT say that one is better than the other, it's apples and oranges. User:Rhobite 21:42, Oct 27, 2004 (UTC) :Agreed, you cannot simply say that one is "better" than the other. But this is not because CDDA does "encoding" while MP3 does something completely different called "compression", but because the domain of MP3 is much greater than that of CDDA. Both are formats for storing PCM digital audio, and from the experience of the average computer user, both are ''overwhelmingly'' used for nothing except 44.1/16/stereo. For such an appropriately restricted application, they are perfectly comparable. One might say "using equipment XYZ and audio samples PQR, 50% of sample of 100 untrained listeners considered MP3 (using encoder MNO with settings JKL and bitrate ABC) to be not noticably worse than its CDDA source", and this would be a perfectly valid, reproducible test. User:Smyth">User:Smyth|– User:Smyth 11:53, 30 Oct 2004 (UTC) ::Fact remains that one can encode to MP3 from a much higher (high-end) quality audio source than the "box" where CDDA needs to fit in. For CDDA one would need to bring quality down, where samplerate, dynamics and bit-depth are concerned. This is not related to "tests" or opinions, this is sheer reality. CDDA has limitations as well, and they can actually be regarded as more important (reproduction-quality wise) than those of MP3. All this as long as it concerns playback quality and nothing more. User:195.64.95.116 16:24, 31 Dec 2004 (UTC) == Sampling rate == The text refers to "available sample frequencies." Would it be possible to define what "sample frequences" or "sample rate" means? :Sampling frequency? User:Smyth">User:Smyth|– User:Smyth 01:46, 8 Nov 2004 (UTC) == Value judgments == Wikipedia articles don't make value judgments or recommendations, such as recommending that non-professionals never have a reason to use lossless compression. In any case, this statement is not true: "Those who will only listen, do not need to use lossless compression, since they won't hear the difference with MP3." You can't make blanket statements like that, some people can indeed tell MP3 - even with a good compressor - from audio that has never been compressed. :They can up to a measured degree. This can be proven and it often has been. Beyond certain high enough bitrates NO HUMAN will be capable of telling the difference.User:195.64.95.116 16:16, 31 Dec 2004 (UTC) Etree and archive.org distribute lossless copies of nearly every show - there is obviously a large group of listeners who feels MP3 is inadequate for their uses. User:Rhobite 23:06, Nov 15, 2004 (UTC) :The fact that MP3 is now often considered a degraded format, surpassed by other formats, has nothing to do with that. It's simply because
:1) there are bad mp3 encoders around (lots of them in fact)
:2) MP3 tends to need some type of special treatment beforehand to reach optimum quality, other formats don't.
:3) MP3 is being used the wrong way a lot, cascaded, with low quality encoding, within mastering mix-CD's and so on.
:I mention the obvious importance in the different ways of use for audio(files), since THAT is the main reason people start to think MP3 is a bad quality format; They use it to re-encode, they start to use it as a professional format, they end up mastering CD's from MP3 files. Of course they shouldn't, MP3 is intended as a final "play and listen" format only, not to be processed further on in any way or form possible. CDDA and MP3 are almost the same in that regard.User:195.64.95.116 16:16, 31 Dec 2004 (UTC) ==Possible Plagiarism== I just searched for info about the use of Tom's Diner in early MP3 work and I found this page: [http://www.secretmaker.com/technopedia/m/mp3/default.html]. Does anyone know what's what? :It looks like this page is a possible Wiki clone? Several pages seem similar to Wiki and it calls itself "Technopedia". 08:16, 14 Feb 2005 (UTC) ::It is a wikipedia clone site. This is explicitly allowed by the GFDL, but they do have to credit the original authors and provide access to the source of the article, which they're not doing. I've listed them on the Mirrors and Forks page at Wikipedia:Mirrors_and_forks/Stu#Secretmaker, as a low compliance site. Thanks for pointing this out. User:Rhobite 08:31, Feb 14, 2005 (UTC) == Incorrect Statement of The Law== I believe this statement: '' However, non-commercial use and distribution of any item, with software codecs included, is by definition free of any relevance or impediments under patent law. '' Is legally incorrect. For example, there is no U.S. law provision allowing for "fair use" of patents, in the sense that any noncommercial or ''de minimis'' use is not an exception for infringement. See 35 USC 271. The only exception to partent infringement that I know of is experimentation to validate that the patent is operative. Perhaps the author was referring to "fair use" in a copyright sense. If so, that makes sense as 17 USC 107 "Limitations on exclusive rights: Fair Use" would apply. As the topic referenced in the article is patents I deleted the sentence. I note that it is unlikely the patent holder would sue an individual who was making non commercial use of the patent, but in theory I think the indivudual has no legal defense due to the noncommercial nature of the use. Would be interesting how this would play out in other countries. == Online music resources == This section seems a non sequitur -- for example, Apple's music store does not use the MP3 format at all. == Patents and details == What parts, exactly, of the algorithm are patented? Also, time-to-frequency conversion and physcoacoustics have much prior art. Should this be inclueded? And we also need to include a description of the algorithm. User:Watsonladd 19:09, Apr 25, 2005 (UTC) == patent == When does the patent expire in the US and other countries?
Mp3
#REDIRECT MP3
See other meanings of words starting from letter:
M
MA | MB | MC | MD | ME | MF | MG | MH | MI | MJ | MK | ML | MN | MO | MP | MR | MS | MT | MU | MW | MX | MY | MZ |Words begining with MP3:
MP3
MP3
Mp3
MP3-PRO
MP3-pro
Mp3-PRO
Mp3-pro
MP3.com
MP3.com
Mp3.com
Mp30dancer
MP38
Mp3hist
MP3PRO
MP3Pro
MP3pro
Mp3PRO
Mp3pro
MP3Search.Ru
MP3tunes
MP3tunes
Mp3tunes
Mp3tunes
MP3_(album)
MP3_blog
MP3_blog
Mp3_blog
Mp3_files
Mp3_files
MP3_Newswire
MP3_Player
MP3_player
MP3_player
Mp3_player
Mp3_player
MP3_players
Mp3_players
MP3_PRO
MP3_pro
Mp3_PRO
Mp3_pro
MP3_sounds
MP3_Surround
MP3_surround
These materials are based on Wikipedia and licensed under the GNU FDL
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