Chair: James Johnston (Send E-mail) Chair: Juergen Herre (Send E-mail) Mission Statement:
This committee has as its scope the theory, study, research, practice, engineering, and other standing issues involving the coding (i.e. bit rate reduction) of audio signals, especially but not limited to methods that use knowledge of human perception in the coding process.
The goal of this committee is to further work, knowledge and interest in subjects within its scope, and to increase awareness of the methods, problems, and standards within the AES. Within its scope, the committee will provide an informal technical forum for discussion of scientific and engineering problems as well as non-technical matters, participate in convention programs at the invitation of Convention Chairs, and work with the editor of the JAES, allowing it to distribute accurate and timely information to the membership.
Areas of ConcentrationCurrent Areas Of Work
- Coding Research and Engineering
- Bit Rate Reduction Theory and Practice
- Human Perception
Recent/Planned Activities
- Parametric Multi-Channel Audio Coding
- Parametric Multi-Object Audio Coding
- Low Delay General Audio Coding
Audio Coding CD-ROM
- 105th AES Convention: Workshop on Perceptual Audio Coding
- 106th AES Convention: Workshop on MPEG-4 Audio
- 17th AES International Conference on High Quality Audio Coding
- 107th AES Convention: Workshop on Internet Audio
- 108th AES Convention: Workshop on MPEG-4 Audio, Version 2
- CD-ROM Project on Coding Distortions. Listener training and education on coding distortions
- 109th AES Convention, Workshop on CD-ROM Project
- 110th AES Convention, Introduction & Introductory Paper on CD-ROM "Perceptual Audio Coders - What To Listen For"
- 111th AES Convention: Release of CD-ROM "Perceptual Audio Coders - What To Listen For"
- 112th AES Convention: Workshop on CD-ROM, Workshop on Tandem Coding (together with AES TC on Perception)
- 113th AES Convention: Workshop on recent MPEG-4 Audio Extensions, Workshop on "Coding of Spatial Audio", 2nd Release of CD-ROM
- 114th AES Convention: Workshop on MPEG-4 Audio Extensions, Workshop on "Coding of Spatial Audio"
- 115th AES Convention: Workshop on MPEG-4 AudioBIFS
- 117th AES Convention: Workshop on Lossless Audio Coding
- 117th AES Convention: Workshop on Spatial Coding of Surround Sound
- 119th AES Convention: Workshop on Next Generation Audio Communications
- 120th AES Convention: Workshop on MPEG Surround Parametric Multi-Channel Audio Coding
- 121st AES Convention: Workshop on Lossless Audio Coding
- 121st AES Convention: Workshop on MPEG Surround
- 123rd AES Convention: Workshop on MPEG Spatial Audio Object Coding (SAOC)
Emerging Technology TrendsA CD-ROM on audio coding artifacts was prepared by the members of the AES Technical Committee on Coding of Audio Signals. This is the first educational/tutorial CD-ROM presented by the AES Technical Council on a particular topic, combining background information with specific audio examples. To facilitate the use of high-quality home playback equipment for the reproduction of the audio excerpts, the disk can also be played back on all standard audio CD players. Available via AES publications!
Over time audio coding has moved beyond the research stage and into use, and it has emerged as a strong force in the consumer market. A variety of implications and trends are visible:
• The consumer can choose various options with regard to quality and means of delivery.
• The frontiers of compression have been pushed further, allowing full bandwidth signals at very low bit rates to the point where some people consider such systems broadcast quality. Examples are the so-called bandwidth-extension technology, Parametric Stereo and Spatial Audio Coding/MPEG Surround, WMA Pro 10.
• Even after a considerable number of previous attempts, an important issue still is how to use low- and broadband- rate Internet connections for piracy-free E-commerce. This is part of the problem of how to use the Internet and how to move current business models into the Internet. First promising steps in this area have been made recently with distribution models that also receive wide consumer acceptance. More such steps have to follow, including openly standardized solutions. It is, however, noted that the problem is not of purely technical nature, involving the expectation of both music producers and consumers. Some demands of this new business form are:
• Watermarking of audio, including compressed audio;
• Support for intellectual property control, licensing, and permissions;
• The trend toward integration of compressed audio, video, film, and graphics, and integration of the demands of the various media requiring sophisticated licensing and permission models.
• There is a consistent trend toward hybrid coding techniques that employ parametric modeling to represent certain signal aspects. While the core of most successful audio coders is still largely based on a classic filterbank-based coding paradigm, the recent success of parametric additions in both market deployment and standardization demonstrates this tendency (again, this includes techniques for bandwidth extension, parametric stereo, and multi-channel coding). Such techniques are also vital for enabling object-oriented representation and rendering of audio signals in a computationally and bitrate-efficient way.
• As an alternative to hybrid model-based techniques, methods are also emerging that use low-rate coding methods previously encountered in speech coding to extend bandwidth in an efficient fashion.
• Also, the role of higher level psychoacoustics/ perception is becoming increasingly important in audio coding. Detection of auditory objects in an audio stream, separation into auditory (as opposed to acoustic) objects, and storage and manipulation as auditory objects is beginning to play a role. Since we have observed that listeners learn to hear new kinds of artifacts over time, it will be interesting to see how the new layer of coding algorithms interact with listeners’ learning to hear them, and what the final outcome will be.
Solid-state and hard drive-based audio is proliferating, and lots of transcoding and direct processing in the compressed and/or transform domain may be necessary in the future. Ten years ago the hardware required to run a real-time audio codec was expensive and difficult to work with. Now, present audio coders work in a fraction of readily available CPU capacity, even for multi-channel coding, and new research may be needed to discover how to use the additional CPU cycles and memory space. Some possibilities are improved psychoacoustic models and sophisticated acoustic scene analysis. Seen overall, the research in audio coding is moving to the extremes, both toward lowest bit rates (very lossy compression with bandwidth extension) and highest bitrates (noiseless/lossless coding for high-resolution audio at high sampling rates/resolutions), as well as the more complex (scene analysis and soundfield synthesis of various sorts). Another open challenge is the development of a truly universal audio coder which delivers state of the art performance for all sorts of input signals, including music and speech, across a wide range of bitrates. As an alternative to a “universal” coder, the marketplace may simply enforce a “many-decoder” model where metadata tells the decoder what is required. As the proliferation of standard, de-facto standard, and specialty codecs continues, this may turn out to be the only viable solution.
Meeting Report:These documents do not necessarily express the official position of the AES on the issues discussed at these meetings, and only represent the views of committee members participating in the discussion. Any unauthorized use of these publications is prohibited. Authorization must be obtained from the Executive Director of the AES: E-mail, Tel: +1 212 661 8528, Address: 60 East 42nd Street, Room 2520, New York, New York 10165-2520, USA.
05/26/2008 TC_CAS Minutes Amsterdam '08
Description: Minutes of TC on Audio Coding at 124th AES Convention, Amsterdam, 05/0810/29/2007 TC_CAS Minutes New York '07
Description: Minutes of TC on Audio Coding at 123rd AES Convention, New York, 10/0706/18/2007 TC_CAS Minutes Vienna '07
Description: Minutes of TC on Audio Coding at 122nd AES Convention, Vienna, 5/0711/24/2006 TC_CAS Minutes San Francisco '06
Description: Minutes of TC on Audio Coding at 121st AES Convention, San Francisco, 10/0609/24/2006 TC_CAS Minutes Paris '06
Description: Minutes of TC on Audio Coding at 120th AES Convention, Paris, 5/0612/15/2005 TC_CAS Minutes New York '05
Description: Minutes of TC on Audio Coding at 119th AES Convention, New York, 12/0506/23/2005 TC_CAS Minutes Barcelona '05
Description: Minutes of TC on Audio Coding at 118th AES Convention, Barcelona, 5/0511/04/2004 TC_CAS Minutes San Francisco '04
Description: Minutes of TC on Audio Coding at 117th AES Convention, San Francisco, 10/0406/23/2004 TC_CAS Minutes Berlin '04
Description: Minutes of TC on Audio Coding at 116th AES Convention, Berlin, 5/0411/14/2003 TC_CAS Minutes New York '03
Description: Minutes of TC on Audio Coding at 115th AES Convention, New York, 10/0304/08/2003 TC_CAS Minutes Amsterdam '03
Description: Minutes of TC on Audio Coding at 114th AES Convention, Amsterdam, 3/0310/22/2002 TC_CAS Minutes Los Angeles '02
Description: Minutes of TC on Audio Coding at 113th AES Convention, Los Angeles, 10/0209/22/2002 TC_CAS Minutes Munich '02
Description: Minutes of TC on Audio Coding at 112th AES Convention, Munich, 5/0212/11/2001 TC_CAS Minutes New York '01
Description: Minutes of TC on Audio Coding at 111th AES Convention, New York, 12/0105/29/2001 TC_CAS Minutes Amsterdam '01
Description: Minutes of TC on Audio Coding at 110th AES Convention, Amsterdam, 5/0110/17/2000 TC_CAS Minutes Los Angeles '00
Description: Minutes of TC on Audio Coding at 109th AES Convention, Los Angeles 9/0008/02/2000 TC_CAS Minutes Paris '00
Description: Minutes of TC on Audio Coding at 108th AES Convention, Paris, 2/0011/04/1999 TC_CAS Minutes New York '99
Description: Minutes of TC on Audio Coding at 107th AES Convention, New York, 9/9909/29/1999 TC_CAS Minutes New York '97
Description: Minutes of the TC on Audio Coding at the 103rd AES Convention in NY, 9/9709/29/1999 TC_CAS Minutes Amsterdam '98
Description: Minutes of TC on Audio Coding at 104th AES Convention, Amsterdam, 5/9805/26/1999 TC_CAS Minutes Munich '99
Description: Minutes of TC on Audio Coding at 106th AES convention, Munich, 5/9912/22/1998 TC_CAS Minutes San Francisco '98
Description: Minutes of TC on Audio Coding at 105th AES Convention, San Francisco 10/98
Other:10/06/2007 Workshop: FROM SAC TO SAOC - RECENT DEVELOPMENTS IN PARAMETRIC CODING OF SPATIAL AUDIO
Description: Slide presentations from workshop W10 chaired by Juergen Herre at the AES 123rd Convention, October 200710/29/2006 Audio Coding Tutorial
Description: Tutorial on Perceptual Audio Coding, presented at 121st AES Convention, October 2006 (Part by Marina Bosi)10/20/2006 Workshop: LOSSLESS AUDIO COMPRESSION — TECHNOLOGY AND FORMATS
Description: Slide presentations from workshop W14 chaired by Tilman Liebchen at the AES 121st Convention, October 200610/16/2006 Workshop: MPEG SURROUND — THE MPEG STANDARD FOR PARAMETRIC MULTICHANNEL AUDIO CODING
Description: Slide presentations from workshop W16 chaired by Juergen Herre at the AES 121st Convention, October 200606/05/2006 Workshop: MPEG SURROUND—RECENT PROGRESS IN PARAMETRIC CODING OF MULTICHANNEL AUDIO
Description: Slide presentations from workshop W9 chaired by Juergen Herre at the AES 120th Convention, May 2006
Committee Members
Antonio Pena Bernd Edler Bernhard Grill Christof Faller David Spector Gerald Schuller Gerhard Stoll Grant Davidson Heiko Purnhagen James Johnston Jens Spille Jon Rowlands Jont Allen Juergen Herre Karlheinz Brandenburg Kenzo Akagiri Louis Fielder Marina Bosi Mark Sandler Markus Erne Martin Dietz Mike Goodwin Mohammed Javed Absar Noel McKenna Schuyler Quackenbush Takehiro Moriya Thomas Sporer Werner Oomen Ye Wang Stefan Geyersberger Enrique Alexandre Michael Kelly Andreas Ehret Hossein Najaf-Zadeh Andre van Schaik Thomas McLaughlin Ricardo Garcia Frank Baumgarte Tilman Liebchen Michelle Daniels Anibal Ferreira Deepen Sinha Gregory Massey Ralf Geiger Regis Rossi Alves Faria Oliver Hellmuth David Trainor
To request membership in this Technical Committee please e-mail the Chair by using the link above.
(C) 2008, Audio Engineering Society, Inc.
