Audio Lossless Coding

Last updated
Audio Lossless Coding
Developed by ISO
Initial releaseMarch 2006;18 years ago (2006-03)
Latest release
RM23
2009;15 years ago (2009)
Type of format Lossless audio
Contained by MP4
Standard ISO/IEC 14496-3
Open format?Yes
Free format?No

MPEG-4 Audio Lossless Coding, also known as MPEG-4 ALS, is an extension to the MPEG-4 Part 3 audio standard to allow lossless audio compression. The extension was finalized in December 2005 and published as ISO/IEC 14496-3:2005/Amd 2:2006 in 2006. [1] The latest description of MPEG-4 ALS was published as subpart 11 of the MPEG-4 Audio standard (ISO/IEC 14496-3:2019) (5th edition) in December 2019. [2]

Contents

MPEG-4 ALS combines a short-term predictor and a long term predictor. The short-term predictor is similar to FLAC in its operation – it is a quantized LPC predictor with a losslessly coded residual using Golomb Rice Coding or Block Gilbert Moore Coding (BGMC). [3] [4] The long term predictor is modeled by 5 long-term weighted residues, each with its own lag (delay). The lag can be hundreds of samples. This predictor improves the compression for sounds with rich harmonics (containing multiples of a single fundamental frequency, locked in phase) present in many musical instruments and human voice.

Features

Software support

As of 2020, there has not been wide acceptance of this format, possibly due to the lack of encoders and decoders available. [8]

A reference implementation of MPEG-4 ALS encoder and decoder (mp4als – e.g. mp4alsRM23) can be obtained at the MPEG-4 ALS homepage and it was also published as ISO/IEC 14496-5:2001/Amd 10:2007/Cor 3:2009. [7]

There is a MPEG-4 ALS Decoder plugin for Winamp player. [9]

On November 11, 2009, the FFmpeg open source project gained an MPEG-4 ALS decoder in its development version. [10] Only a subset of the format is currently supported.

History

In July 2002, the Moving Picture Experts Group issued a call for proposals of lossless audio coding procedures to be sent in before December. Seven companies submitted their proposals which were examined taking into consideration compression efficiency, complexity and flexibility. By July 2003, Lossless Predictive Audio Compression (LPAC) was selected as the first draft for the future standard. The reference model was further developed under participation of Technische Universität Berlin (TUB), RealNetworks, and Nippon Telegraph and Telephone (NTT).

See also

Related Research Articles

<span class="mw-page-title-main">MP3</span> Digital audio format

MP3 is a coding format for digital audio developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg, with support from other digital scientists in other countries. Originally defined as the third audio format of the MPEG-1 standard, it was retained and further extended—defining additional bit rates and support for more audio channels—as the third audio format of the subsequent MPEG-2 standard. A third version, known as MPEG-2.5—extended to better support lower bit rates—is commonly implemented but is not a recognized standard.

<span class="mw-page-title-main">Moving Picture Experts Group</span> Alliance of working groups to set standards for multimedia coding

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-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal standard ISO/IEC 14496 – Coding of audio-visual objects. Uses of MPEG-4 include compression of audiovisual data for Internet video and CD distribution, voice and broadcast television applications. The MPEG-4 standard was developed by a group led by Touradj Ebrahimi and Fernando Pereira.

<span class="mw-page-title-main">Super Audio CD</span> Read-only optical disc for high-fidelity audio storage

Super Audio CD (SACD) is an optical disc format for audio storage introduced in 1999. It was developed jointly by Sony and Philips Electronics and intended to be the successor to the compact disc (CD) format.

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.

WavPack is a free and open-source lossless audio compression format and application implementing the format. It is unique in the way that it supports hybrid audio compression alongside normal compression which is similar to how FLAC works. It also supports compressing a wide variety of lossless formats, including various variants of PCM and also DSD as used in SACDs, together with its support for surround audio.

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.

<span class="mw-page-title-main">High-Efficiency Advanced Audio Coding</span> Audio codec

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.

MPEG-4 Part 2, MPEG-4 Visual is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosine transform (DCT), similar to previous standards such as MPEG-1 Part 2 and H.262/MPEG-2 Part 2.

FAAC is a software project which includes the AAC encoder FAAC and decoder FAAD2. It supports MPEG-2 AAC as well as MPEG-4 AAC. It supports several MPEG-4 Audio object types, file formats, multichannel and gapless encoding/decoding and MP4 metadata tags. The encoder and decoder is compatible with standard-compliant audio applications using one or more of these object types and facilities. It also supports Digital Radio Mondiale.

<span class="mw-page-title-main">MPEG-4 SLS</span> Extension to the MPEG-4 Audio standard

MPEG-4 SLS, or MPEG-4 Scalable to Lossless as per ISO/IEC 14496-3:2005/Amd 3:2006 (Scalable Lossless Coding), is an extension to the MPEG-4 Part 3 (MPEG-4 Audio) standard to allow lossless audio compression scalable to lossy MPEG-4 General Audio coding methods (e.g., variations of AAC). It was developed jointly by the Institute for Infocomm Research (I2R) and Fraunhofer, which commercializes its implementation of a limited subset of the standard under the name of HD-AAC. Standardization of the HD-AAC profile for MPEG-4 Audio is under development (as of September 2009).

<span class="mw-page-title-main">MP4 file format</span> Digital format for storing video and audio

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.

MPEG Surround, also known as Spatial Audio Coding (SAC) is a lossy compression format for surround sound that provides a method for extending mono or stereo audio services to multi-channel audio in a backwards compatible fashion. The total bit rates used for the core and the MPEG Surround data are typically only slightly higher than the bit rates used for coding of the core. MPEG Surround adds a side-information stream to the core bit stream, containing spatial image data. Legacy stereo playback systems will ignore this side-information while players supporting MPEG Surround decoding will output the reconstructed multi-channel audio.

The ISO base media file format (ISOBMFF) is a container file format that defines a general structure for files that contain time-based multimedia data such as video and audio. It is standardized in ISO/IEC 14496-12, a.k.a. MPEG-4 Part 12, and was formerly also published as ISO/IEC 15444-12, a.k.a. JPEG 2000 Part 12.

Unified Speech and Audio Coding (USAC) is an audio compression format and codec for both music and speech or any mix of speech and audio using very low bit rates between 12 and 64 kbit/s. It was developed by Moving Picture Experts Group (MPEG) and was published as an international standard ISO/IEC 23003-3 and also as an MPEG-4 Audio Object Type in ISO/IEC 14496-3:2009/Amd 3 in 2012.

References

  1. ↑ ISO (2006). "Audio Lossless Coding (ALS), new audio profiles and BSAC extensions – ISO/IEC 14496-3:2005/Amd 2:2006". ISO. Retrieved 2009-10-07.
  2. ↑ ISO/IEC (2019). "ISO/IEC 14496-3:2019: Information technology — Coding of audio-visual objects — Part 3: Audio" (PDF). ISO. Retrieved 2022-01-01.
  3. ↑ Tilman Liebchen & Yuriy Reznik (2004-04-03). "MPEG-4 ALS: an Emerging Standard for Lossless Audio Coding" (PDF). Data Compression Conference. Retrieved 2010-09-03.
  4. ↑ Tilman Liebchen; Takehiro Moriya; Noboru Harada; Yutaka Kamamoto; Yuriy A. Reznik (2005-08-03). The MPEG-4 Audio Lossless Coding (ALS) Standard – Technology and Applications (PDF). 119th Audio Engineering Society Convention, 2005 October 7–10 New York. Audio Engineering Society. Retrieved 2009-10-08– via Technische Universität Berlin.
  5. ↑ Noboru Harada; Takehiro Moriya & Yutaka Kamamoto (2009-05-07). "MPEG-4 ALS: Performance, Applications, and Related Standardization Activities". NTT Technical Review. Retrieved 2009-10-08.
  6. ↑ ISO/IEC 14496-3:200X/PDAM 2 – ALS Simple Profile and Transport of SAOC – N10826, 2009-07-03, archived from the original (DOC) on 2014-07-29, retrieved 2009-10-15
  7. 1 2 Communication Systems Group (2009-10-01). "MPEG-4 Audio Lossless Coding (ALS)". Technische Universität Berlin. Archived from the original on 2019-03-21. Retrieved 2019-03-21.
  8. ↑ Hydrogenaudio Knowledgebase (2006). "Lossless comparison". Hydrogenaudio Knowledgebase. Retrieved 2022-01-01.
  9. ↑ "MPEG-4 ALS Decoder plugin 1.00 for Winamp". Codecs.com. 2007-06-05. Retrieved 2009-10-08.
  10. ↑ FFmpeg (2009-11-11). "FFmpeg-cvslog r20517". FFmpeg. Archived from the original on 2010-02-11. Retrieved 2009-11-20.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.