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 The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

/ IEC 14496-3:2005/Amd 2:2006 in 2006. The latest description of MPEG-4 ALS was published as subpart 11 of the

MPEG-4 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 ...

Audio standard (ISO/IEC 14496-3:2019) (5th edition) in December 2019. MPEG-4 ALS combines a short-term predictor and a long term predictor. The short-term predictor is similar to

FLAC FLAC (; Free Lossless Audio Codec) is an audio coding format for lossless compression of digital audio, developed by the Xiph.Org Foundation, and is also the name of the free software project producing the FLAC tools, the reference software ...

in its operation – it is a quantized LPC predictor with a losslessly coded residual using Golomb Rice Coding or Block Gilbert Moore Coding (BGMC). 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

* Support for PCM resolutions of up to 32-bit including floating-point * Arbitrary sampling rates * Multi-channel / multi-track support (up to 65536 channels) *

Streaming Streaming media refers to multimedia delivered through a network for playback using a media player. Media is transferred in a ''stream'' of packets from a server to a client and is rendered in real-time; this contrasts with file downl ...

* Seekable (fast random access to any part of the encoded data). * Optional storage in MP4 file format; can be multiplexed with video and other media content supported by the MP4 container. * An MPEG-4 Audio profile "ALS Simple Profile", invoked with "-sp1" in the reference encoder.

Software support

, there has not been wide acceptance of this format, possibly due to the lack of encoders and decoders available. A

reference implementation In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The 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. There is a MPEG-4 ALS Decoder plugin for Winamp player. On November 11, 2009, the

FFmpeg FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing vide ...

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

project gained an MPEG-4 ALS decoder in its development version. Only a subset of the format is currently supported.

History

In July 2002, the

Moving Picture Experts Group 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 ...

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 (TU Berlin; also known as Berlin Institute of Technology and Technical University of Berlin, although officially the name should not be translated) is a public university, public research university located in Berlin, Germany. It was the first ...

(TUB), RealNetworks, and

Nippon Telegraph and Telephone (NTT) is a Japanese telecommunications holding company headquartered in Tokyo, Japan. Ranked 55th in ''Fortune'' Global 500, NTT is the fourth largest telecommunications company in the world in terms of revenue, as well as the third largest pu ...

(NTT).

References

External links

MPEG-4 ALS homepage – Technische Universität Berlin

MPEG-4 Audio Lossless Coding (ALS) – MultimediaWiki

– NTT (2007) * ttp://www.reznik.org/software.html#ALS Technical papers describing design of residual coding and quantization algorithms in MPEG-4 ALS codec
Announcement on ACN Newswire

Technical specifications (ISO/IEC 14496-3:2005/Amd 2:2006)
(not free)
Official MPEG web site
{{Compression software implementations MPEG-4 Lossless audio codecs

Features

Software support

History

See also

References

External links