Multiple Audio Tracks
Posted: 28 Mar 2011 12:56
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
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
