No sound when converting AVI to DVD

[vfwfw]

I have some AVI files which play OK on my PC, however when I convert them to MPEG's and burn them to a DVD, the sound disappears.
I have used GSpot to confirm that the audio codec on the AVI's is AC3 which I have 6 different codecs installed on my PC.
I have been converting AVI's to DVD's using TMPGEnc and TMPGEnc Author for ages and have not had any problems before. The only difference is that the AVI's I have burnt before are those captured from my Video Camera, and these new ones are files given to me by a friend, so I don't know what their source is.
I thought that if the codec was supported by the PC (which GSpot confirms) there should not be any problems??? Is there anything else I should be doing???

[redwudz]

There are different ways to encode AC3. Could be you have a odd one. I assume you insert the AC3 when you author with TDA?

Probably a lot of ways to fix the audio, assuming that's the problem. I use VirtualDub Mod along with the AC3 ACM Decompressor to input the audio. Then save it out as a WAV and re-encode it with ffmpeggui to AC3. I've never had any problems with ffmpeggui AC3 and TDA. ffmpeggui only does 2 channel, though.

[vfwfw]

Thanks Redwudz,

I have been using TMPGEnc to split the AVI into their Video and Audio streams, and thought that this audio strean was the AC3 stream. From searching this forum I now believe that I have to use something like Virtualdubmod to separate the AC3 stream, use TMPGEnc to separate the video stream and then load both these streams into TMPGEnc Author.

Is this right?

[redwudz]

That's the method I generally use. I save out the audio as a WAV, convert to AC3 with ffmpeggui and add that in when I author as the audio source. TMPGEnc can do AC3 with the plugin, but I don't use it. There are other ways to do all this, this is just what works for me. If you have a video with DVD compliant 5.1 AC3 audio, then you just mux it out and add it when you author.

[vfwfw]

Is there any reason why you save it out as a wav file rather than go straight to an AC3 file? The version of Virtualdubmod I have has that option (under Streams/Stream List/Demux).

[redwudz]

If it already has AC3 in the original file, sure, go ahead and demux it out. Then take that file and add it in when authoring. I had assumed you had already tried that. Some methods of encoding AC3 may not be compliant with all players. I'm not sure that even the ffmpeggui versions won't have problems with a few players.