First Look:

Will MPEG Surround replace Dolby Digtal 5:1 for high quality audio streaming?

By Bernard Cole
iApplianceWeb
(05/30/06, 6:54 AM GMT)

Paris, France – At the Audio Engineering Society (AES) Expo details were revealed on the nature of  MPEG Surround, a new audio standard that after its final draft publication in July could knock Dolby from its spot as the defacto standard for multichannel audio compression.

The big thing going for MPEG Surround is that it is supposed to allow allows broadcasters and content providers to high-quality surround sound to MP3 files or other MPEG audio streams for Internet Protocol TV, mobile entertainment and Internet, without setting aside additional channels for transmission.

Based on a highly efficient parametric coding algorithm, it is able to reduce bit-rate requirements for high-quality multichannel audio compression, and maintain backward compatibility with existing stereo equipment.

The technology can transform mono or stereo audio signals compressed in MP3, MPEG-4 Advanced Audio Codec or MPEG-4 HE-AAC into high-quality multichannel surround audio with only a slight increase in data rate, compared to the existing Dolby spec, which can operate only when severe transmission-channel bandwidth limitations are imposed.

Unlike the 5.1-channel Dolby Digital, which requires proprietary multichannel audio compression separate from MP3 and other MPEG audio codecs, MPEG Surrond can be implemented by simply replacing a stereo encoder with a surround encoder, with no other changes in the existing audio streaming infrastructure.

MPEG Surround, because of its minimal infrastructure re-engineering brings a number of high end audio capabilities down the cost cure, such as the ability to transmit a compact set of parameters representing the spatial image of the original surround-sound signal along with an automatic mono or stereo downmix as well as a separate optional, hand-optimized downmix signal.

As this spatial side information is sent in an auxiliary data field, a receiving device's MPEG Surround decoder can expands the transmitted downmix signal into a high-quality multichannel output.

In a low end receiver, with no MPEG Surround decoder, this information in the  spatial parameters is ignored and it decodes the stream as stereo. MPEG Surround's surround-enhancement data rate is scalable from 3 to 32 kbits/second.

Because it does not require broadcasters or content owners to send (or store) both stereo and multichannel versions of audio, the new specification, when finally available will be rapidly adopted with potential applications in digital radio systems and Internet streaming, as well as multichannel services for mobile-TV broadcasts.

For more information, go to www.aes.org.  

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