Tuesday, October 8 1:00 pm 4:00 pm
W15: CODING OF SPATIAL AUDIO YESTERDAY, TODAY, TOMORROW
Chair: Christof Faller, Agere Systems, Murray Hill, NJ
Frank Baumgarte, Agere Systems, Murray Hill, NJ
Mark Davis, Dolby, San Francisco, CA, USA
Martin Dietz, Coding Technologies, Nürnberg, Germany
Gerald Schuller, Fraunhofer Institute, Ilmenau, Germany
Thomas Sporer, Fraunhofer AEMT, Ilmenau, Germany
Low bitrate audio coding has become ubiquitous in many of today's audio systems, most of which are able to handle stereo or multichannel audio signals. A closer examination of issues related to the compression of spatial audio reveals a number of complex perceptual and coding issues which need to be considered in order to achieve optimum coder performance. While a wealth of different approaches have evolved over the recent decade, there is no single technique serving all purposes equally well.
This workshop offers a review of the principles and practical approaches for coding of spatial audio, discusses the different dimensions of the trade-off 'bit-rate vs. spatial quality', and characterizes commonly used coders with respect to these aspects.
1. Introduction into the topic and short overview of the workshop by Christof Faller
2. Spatial Perception by Thomas Sporer
This presentation reviews spatial perception relevant to reproduction and coding of spatial audio.
3. Historical Development of Spatial Audio Reproduction and Transmission by Mark Davis
The historical development of stereophonic and multichannel audio reproduction is presented. This includes the description of early experiments with multi-speaker and two-speaker stereophony. Also early techniques for pseudo-stereophony etc. are described. For the historical development of spatial audio transmission, sum/difference transmission for FM radio stereophony is described and new techniques based on perceptual audio coding are briefly mentioned.
4. Coding of Stereophonic Signals by Gerald Schuller
Traditional ways of encoding of stereo audio signals such as:
- separate coding (fails for certain signals)
- L/R coding and S/D coding, BMLD consideration
- redundancy reduction, irrelevancy reduction
- intensity stereo
- matrices as used in popular coders
5. Parametric Stereo for very low Bitrate Stereo Coding by Martin Dietz
This presentation describes the idea of parametric stereo coding: a mono signal, down-mixed from the stereo source and compressed by powerful modern coding algorithms, is converted back into stereophonic sound by means of a coded parametric description of the spatial properties of the original signal.
6. Future Directions for Coding of Spatial Audio by Frank Baumgarte
Describes the technique and philosophy behind Binaural Cue Coding (BCC) and other
potential forward looking technologies for coding of spatial audio.
7. Conclusions by Christof Faller