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MP3 is a coding format for digital audio developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg. It was designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners; for example, compared to CD-quality digital audio, MP3 compression can commonly achieve a 75–95% reduction in size, depending on the bit rate. In popular usage, MP3 often refers to files of sound or music recordings stored in the MP3 file format (.mp3) on consumer electronic devices.
The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and file formats for various applications. Together with JPEG, MPEG is organized under ISO/IEC JTC 1/SC 29 – Coding of audio, picture, multimedia and hypermedia information.
MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) practical.
MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, which permit storage and transmission of movies using currently available storage media and transmission bandwidth. While MPEG-2 is not as efficient as newer standards such as H.264/AVC and H.265/HEVC, backwards compatibility with existing hardware and software means it is still widely used, for example in over-the-air digital television broadcasting and in the DVD-Video standard.
MPEG-1 Audio Layer II or MPEG-2 Audio Layer II is a lossy audio compression format defined by ISO/IEC 11172-3 alongside MPEG-1 Audio Layer I and MPEG-1 Audio Layer III (MP3). While MP3 is much more popular for PC and Internet applications, MP2 remains a dominant standard for audio broadcasting.
Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. It was designed to be the successor of the MP3 format and generally achieves higher sound quality than MP3 at the same bit rate.
MPEG-4 Part 3 or MPEG-4 Audio is the third part of the ISO/IEC MPEG-4 international standard developed by Moving Picture Experts Group. It specifies audio coding methods. The first version of ISO/IEC 14496-3 was published in 1999.
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time.
Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech audio coding standard developed based on Adaptive Multi-Rate encoding, using a similar methodology to algebraic code-excited linear prediction (ACELP). AMR-WB provides improved speech quality due to a wider speech bandwidth of 50–7000 Hz compared to narrowband speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by Nokia and VoiceAge and it was first specified by 3GPP.
G.722 is an ITU-T standard 7 kHz wideband audio codec operating at 48, 56 and 64 kbit/s. It was approved by ITU-T in November 1988. Technology of the codec is based on sub-band ADPCM (SB-ADPCM). The corresponding narrow-band codec based on the same technology is G.726.
Harmonic Vector Excitation Coding, abbreviated as HVXC is a speech coding algorithm specified in MPEG-4 Part 3 standard for very low bit rate speech coding. HVXC supports bit rates of 2 and 4 kbit/s in the fixed and variable bit rate mode and sampling frequency of 8 kHz. It also operates at lower bitrates, such as 1.2 - 1.7 kbit/s, using a variable bit rate technique. The total algorithmic delay for the encoder and decoder is 36 ms.
High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496–3. It is an extension of Low Complexity AAC (AAC-LC) optimized for low-bitrate applications such as streaming audio. The usage profile HE-AAC v1 uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. The usage profile HE-AAC v2 couples SBR with Parametric Stereo (PS) to further enhance the compression efficiency of stereo signals.
TwinVQ is an audio compression technique developed by Nippon Telegraph and Telephone Corporation (NTT) Human Interface Laboratories in 1994. The compression technique has been used in both standardized and proprietary designs.
These tables compare features of multimedia container formats, most often used for storing or streaming digital video or digital audio content. To see which multimedia players support which container format, look at comparison of media players.
Program stream is a container format for multiplexing digital audio, video and more. The PS format is specified in MPEG-1 Part 1 and MPEG-2 Part 1, Systems. The MPEG-2 Program Stream is analogous and similar to ISO/IEC 11172 Systems layer and it is forward compatible.
MPEG-4 Part 14, or MP4, is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images. Like most modern container formats, it allows streaming over the Internet. The only filename extension for MPEG-4 Part 14 files as defined by the specification is .mp4. MPEG-4 Part 14 is a standard specified as a part of MPEG-4.
The MPEG-4 Low Delay Audio Coder is audio compression standard designed to combine the advantages of perceptual audio coding with the low delay necessary for two-way communication. It is closely derived from the MPEG-2 Advanced Audio Coding (AAC) standard. It was published in MPEG-4 Audio Version 2 and in its later revisions.
G.719 is an ITU-T standard audio coding format providing high quality, moderate bit rate wideband audio coding at low computational load. It was produced through a collaboration between Polycom and Ericsson.
Part 3 of the MPEG-2 standard defines audio coding:
References
- ↑ M. Nilsson (November 2000). The audio/mpeg Media Type. Network Working Group. doi: 10.17487/RFC3003 . RFC 3003.Proposed Standard.
- ↑ S. Casner; P. Hoschka (July 2003). MIME Type Registration of RTP Payload Formats. Network Working Group. doi: 10.17487/RFC3555 . RFC 3555.Proposed Standard. Obsoleted by RFC 4855, 4856. Updated by RFC 3625, 4629.
- ↑ Patel K, Smith BC, Rowe LA (1993-09-01). "Performance of a software MPEG video decoder". Proceedings of the first ACM international conference on Multimedia - MULTIMEDIA '93. ACM Multimedia. New York City: Association for Computing Machinery. pp. 75–82. doi:10.1145/166266.166274. ISBN 978-0-89791-596-0. S2CID 3773268. Reference 3 in the paper is to Committee Draft of Standard ISO/IEC 11172, December 6, 1991.
- ↑ "ISO/IEC 11172-3:1993 - Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s -- Part 3: Audio". ISO. 1993. Retrieved 2010-07-14.
- ↑ "ISO/IEC 13818-3:1995 - Information technology -- Generic coding of moving pictures and associated audio information -- Part 3: Audio". ISO. 1995. Retrieved 2010-07-14.
- ↑ "Philips DCC System Description Draft". Archive.org. Philips Consumer Electronics B.V. September 1994. Retrieved 14 April 2021.
The padding bit [...] indicates whether the current frame has a 'dummy' slot
- 1 2 "MPEG Audio Frame Header". 2003-08-03. Archived from the original on 2015-02-08. Retrieved 2009-05-29.
- ↑ "MPEG-1 audio layer 1". TheFreeDictionary.com.
