Audio issues

[moses6533]

Avidemux is a great tool. But I have run into a couple of issues.
Trying to get all my videos to mp4.

Problems.
1) quite a few mkvs became out of sync when converting to mp4 with direct copy, tried re-encoding the audio and using the shift but no matter what i set it to it didn't seem to shift the audio. Workaround was that i used mkvextractor and mp4box to remux the mkv to mp4 and no sync issues.

2) losing audio channels when encoding just the audio, mp4 to mp4. Basically the movie soundtrack comes across but no the voice channels....i guess that's how it works. Details, i tried different bit rates, drc, gain, re-sampling, all with the same result of lost voice channels. However, that was just on a couple videos. i did not try remixing the audio to something else like Dolby or 5.1, the audio was AC3 5.1 to begin with. I even tried converting it to mkv ac3 in AVIdemux, but again lost voices.
I'm running the whole thing through handbrake now, and will grab the new audio from that and mux it to the original video, to avoid re-encoding the original video, not sure why it will work in Handbrake, i use AAC (faac) in both. I am fairly certain it is the channels thing, but haven't tested that theory, did check one of the videos that did work though and it was mixed to 2 channel, but even though i chose 384kbps as the rate it ended up being 192kbps....that's ok, but pretty far off, the source audio was 640kbps.

3) the information section seems to report every audio stream at 128kbps even though i know they all vary, the frequency seems to be accurate though.

[Jan Gruuthuse]

Are you using the latest avidemux 2.6.1 r8397? Check the Main Menu -> Audio -> Select Track. Up to 4 tracks can be handled there.
When using for audio: copy, the audio should not drop any channels.
When re-encoding audio tracks 5.1 or bigger. There is an issue of channel mapping from the used encoding. See this thread: AC3 5.1 to AAC 5.1
If audio track is DTS