Multiple Audio Tracks

[Adamski11]

Hi

We use the free features of Quicktime to join multiple mp4 movie clips together into a single movie. We use Quicktime because we've found it produces much more accurate edits than editing with FFMpeg or MP4 Box which will usually cause audio sync to be lost as each edit is added. However we can't play in Quicktime because of its bugs with mp4 files audio sync. VLC plays the created files with perfect audio sync but introduces a new problem. When quicktime creates the multi clip file it appears to join the video into one long single track but stores the audio as individual tracks. Every other player we've tried correctly plays the audio as the movie is viewed but VLC doesn't. It starts playing with Audio track 1 selected and then after the first movie segment is passed there is no audio unless the user manually selects the next audio track each time. I don't understand why VLC differs from other players in this respect and it is really annoying because it turns out that VLC is the only player we've found which will keep perfect audio sync throughout the movie, if only it would automatically move to the next audio track when the current one ends.

I'm just wondering if anyone knows of a way to fix this. I've tried out ffmbc which has an option to combine audio tracks, but this is based on ffmpeg which unfortunatly doesn't accept the mp4 elst edits quicktime uses in creating the file.

Many thanks
Adam

[Rémi Denis-Courmont]

Normally, VLC wil reselect an audio track when the current track ends. So it may either be that the track is not ending in the file. Or VLC's MP4 parser fails to detect the situation, in which case you should probably file a bug and submit a patch.

One work-around is to render all tracks:

Code: Select all

vlc --sout-all --sout '#display'

but I admit it's an hack.

[Adamski11]

Hi

Many thanks for your response. Unfortunately using the command line with --sout-all doesn't work (the file plays with just track 1 selected as before) which seems odd. I'm not sure what the --sout '#display' option does as it is not accepted and I can't find any documentation on it, but from reading VLC help it seems just using --sout-all should have done the trick but didn't for some reason.

Any other ideas gratefully receied!

Thanks
Adam

[Rémi Denis-Courmont]

Works fine here (VLC 1.1).

[Adamski11]

I'm running V1.1.8 so I think it must be related to the specific files which have been created using Quicktime. I've posted a ticket with an example file in the hope this may get picked up.

[gidra]

I also experienced the same kind of problem with DVD disks. Please refer to my post : viewtopic.php?f=2&t=89502

[MOVGal]

Hi there! Sorry for the late response, but I'm still experiencing audio sync issues -- even after the suggested fixes. Like Adamski11, the issues only occur in Quicktime. VLC (the best video player ever) has all the right and perfected codecs to play the completed product just fine. Unfortunately, Quicktime is the primary player of my industry. Can anyone PLEASE, PLEASE, PLEASE help me out? Speaking of audio codecs, has anyone ever used Klipsch speakers before? Looking for something to hook up to my computer, but I don't know what to use. Thanks!