1. Shift audio
I use ffmpeg / avconv quite often ... and usually I hate it. Those tools do what they are instructed to do about 30% of the time. I could give you countless examples but I don't want to start flame war, so please help me with my current problem (really easy one).
I wanted to shift audio (content is standard mp4 file with aac and h264 tracks), so I have found a "highly upvoted" solution:
https://superuser.com/a/983153/758887
the only problem with it is that it doesn't work. I downloaded latest stable ffmpeg (even on windows as in the thread, so it's version was 3.4.1) and executed command without changing literaly anything:
ffmpeg.exe -i "movie.mp4" -itsoffset 3.84 -i "movie.mp4" -map 0:v -map 1:a -vcodec copy -acodec copy "movie-audio-delayed.mp4"
Result was no shift (I expected audio to be 3.84s late).
2. Remove MPEG4 atoms
I would be also grateful if you could recommend some tool for removing MPEG4 boxes from content. For examining MPEG4 content I use MP4 Explorer / Codec Visa (limited) on Windows and AtomicParsley on Linux, however they only print atoms and I would like to edit / remove them. For example MP4Box can remove whole moov->track with "-rem" option but what if I would like to remove moov->track->edts only?