GNOME Bugzilla – Bug 400550
support for mp3 surrround format
Last modified: 2008-05-26 10:53:40 UTC
+++ This bug was initially created as a clone of Bug #398196 +++ (Edited for brevity): Rhythmbox doesn't handle multichannel mp3 files properly. They are playable only in stereo. Sample multichannel files: MP3: http://www.all4mp3.com/music/ MP3: ftp://ftp.tnt.uni-hannover.de/pub/MPEG/audio/mpeg2/compliance/testdata/test23.tar.gz Way to reproduce: Import and play in rhythmbox. Actual results: The file plays in stereo only. Expected results: Always play the file and an option to playing it in stereo or multichannel (one could be default). Other information: I would like to see an option (like in vlc for example) for how may channels i would like to listen (1.0 mono, 2.0 stereo, 2.1, 4.0, 4.1, 5.0, 5.1 multichannel). The default playback channel could be recognised from the file (5.1 files at 5.1 channels) or always stereo (downmix), but add an option to listen the multichannel file in multichannel surround. Most of the files can be played in vlc or mplayer with full multichannel surround.
These appear to be mp3 files in 'mp3 surround' format. The fact that they are played back in stereo on 'normal' mp3 players is a feature of the format. If I'm not mistaken, the 'mp3 surround' format is closed and there are no acceptably-licensed libraries that support this format yet either. In any case, you would need to request support for this format from upstream libraries, GStreamer itself does not contain decoders, we only wrap them into GStreamer plugins. When playing the file in vlc or mplayer I can't find any indication that more than 2 channels are decoded. - what versions of VLC and mplayer have you tried this with (and what's the source/distro these are from)? - can you point us to an open-source library or tool that implements this? - can you point us to a place where format specifications are available?
I cannot say more than what you can read here: http://www.iis.fraunhofer.de/fhg/iis/bf/amm/mp3sur/index.jsp >>If I'm not mistaken, the 'mp3 surround' format is closed and there are no >>acceptably-licensed libraries that support this format yet either. I don't know, but i'm afraid it seems so. One important thing for that: There are 2 kinds of multichannel mp3's! One is the MP3 Surround and the other is the MP3 SX (fake surround informations from regulary stereo mp3's). Maybe the samples from http://www.all4mp3.com/music/ are MP3 SX, or differently encoded, because these samples are played as stereo in vlc too. But if i make MP3-Surround with BeHappy (http://www.gotdotnet.com/workspaces/workspace.aspx?id=1bb59ddf-901b-43a5-bd54-b0999e8e223e) that use the Aud-X (http://www.aud-x.com/) encoder, than vlc (0.8.5 debian) can play this mp3 file in 5.1 surround, gstreamer gives noises and say stereo. As you said, all surround MP3's are compatible with the existing decoders, and can be played with these in stereo (as for the Aud-X encoder, gstreamer not work that way). (Sorry, but i have no more information for that atm. I will look around and post more when i find something.)
Ok, let's close this bug for now then as nobody knows details and there are apparently no free decoder libraries supporting these formats.