MP3Surround

MP3 Surround

Introduction

MP3 Surround is a new type of MP3 that supports 5.1 channels of audio. MP3 Surround is a new format, it has been developed by the fathers of MP3, the Fraunhofer IIS and Thomson in 2004. MP3 Surround files have the extension *.mp3 like normal stereo MP3 files. That is possible as MP3 Surround encoded MP3-files are completely backwards compatible with standard MP3. Normal Hardware and Software MP3-players treat and report MP3 Surround encoded MP3 files as standard stereo MP3 as they do not recognize the surround extension.

So everyone might already have some MP3 Surround encoded MP3 files but does not know it ...

Players for MP3 Surround

Due to the backwards compatibility to MP3, any hardware and software MP3 player should be able to play MP3 Surround encoded files without any problem - although in stereo only. For the playback of the 5.1 content of MP3 Surround files, only three software-based possibilities exist at the moment: there is a Winamp plugin and a standalone player, both provided by all4mp3.com. The newest DivX player in the version 6.3.x and above can decode DivX-encoded movies with an MP3 Surround encoded audio layer.

Internet Streaming

Official streaming solutions for broadcasting MP3 Surround across the internet do not exist at the moment - but that might change sooner or later. Inofficial streaming solutions might be possible after tweaking the Icecast streaming server or by using the built in streaming capabilities of the VLC media player.

MP3 Surround Technology

The MP3 backwards compatibility of MP3 Surround has been achieved by downmixing six discrete audio channels to two stereo channels (!) while a third channel (the "surround" channel) outside the stereo MP3 frames contains the dispatching information (the surround info) necessary to get back the full 5.1 content. This third channel is invisible for normal MP3 players (as it is outside the defined MP3 frame structures), they treat the surround channel as they would treat id3 tags: they don't recognize them for playback. The data overhead needed for the third surround channel is 16 kbit/s, which allows for file sizes similar to standard stereo MP3 files.

Encoding of MP3 Surround

There are two ways of encoding MP3 Surround files, for TMB interesting is only the mp3SX converter:

• mp3sEnc: allows to encode mono MP3, stereo MP3, and to encode 6-channel MP3 Surround with 6 discrete channels by encoding one interleaved 6-channel WAV file or by encoding five (5.0) and six (5.1) mono WAV files. It supports only cbr bitrats: 128 / 160 / 192 / 224 / 256 / 320kbps. For TMB uploads this encoder is rather useless as there are no available non-commercial live DJ mix sets or broadcasts in 5.1 surround sound. However, one can also use it as a high quality free to use Fraunhofer stereo MP3 encoder.
• mp3SX: this converter is much more important for TMB members than the mp3sEnc encoder as it requires already existing 44.1kHz stereo MP3-files as input. It upgrades them to MP3 Surround files. Details are given below.

External links

• http://all4mp3.com Software, demos, information, and various mp3 resources
• http://mp3surround.com - Demo content, information and evalution software