Ok, this is probably one of the most commonly asked questions, so I try to explain it very shortly.
In cases where you want to re-encode your existing DivX into VCD or SVCD format using TMPGEnc and the DivX has AC3 surround audio in it, TMPGEnc gives you an error "Audio source not recognized or not supported" or something similiar.
This happens because TMPGEnc really doesn't know how to handle AC3 audio and therefor it has to be removed from the video file and downmixed to stereo WAV file (or MP2).
There's really no easy way to do it, but this is one what I've found after searching a LOT -- courtesy of http://www.vcdhelp.com/ so thank them, not me.
Go to http://www.doom9.net and download GraphEdit. Install Nimo codec pack and either install it in full or so that you get WAVE dest filter installed to your system.
<-------this part is copy/paste from VCDhelp.com's forums------->
Open GraphEdit, open the AVI/DivX, render media file.
Delete the DivX Decoder Filter, Video Renderer and Default Direct Sound devide.
Graph, insert filters (ctrl F), Direct Show Filter
Add one Wav Dest and one Filewriter. When filewriter asks you for a name tell it to use whatever.wav
Connect the output from Morgan Stream Switcher to Wav Dest, connect Wave Dest to Filewriter. To do this just click and drag your mouse from the "output box" from one filter to the input box on the next filter.
Now select Graph and then play, or just hit the play button. Wait afew minutes. Now you got a perfect wav file. You will most likely have to lower the sample rate to 44100 for it to work with a SVCD or VCD. Use SSRC for this.
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Full article and additional infos related to this are in here:
