[FFmpeg-user] MPEG-4/WAV container for quick A/V sync tweaking

[Andrew Berg]

On 2011.04.18 03:56 PM, Olivier Guilyardi wrote:
> Okay, yes H.264, not sure about AVC. Should be.
H.264 and AVC (and MPEG-4 Part 10) are all names for the same video
compression standard.
> Actually, the original data is
> in a 3GP container, which FFmpeg reports as:
>
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/VID_20110418_110132.3gp':
>   Metadata:
>     major_brand     : 3gp4
>     minor_version   : 768
>     compatible_brands: 3gp43gp6
>   Duration: 00:00:07.47, start: 0.000000, bitrate: 2033 kb/s
>     Stream #0.0(eng), 1, 1/24000: Video: mpeg4, yuv420p, 720x480 [PAR 1:1 DAR
> 3:2], 1/24, 2030 kb/s, 23.94 fps, 24 tbr, 24k tbn, 24 tbc
That's ambiguous, but I think FFmpeg reports AVC/H.264 as h264 instead
of mpeg4 (which means your original is MPEG-4 Part 2). I'm pretty sure
3GP supports MPEG-4 Part 2. You can always use MediaInfo to find out
exactly what you have.
> Can I use FFmpeg from the command line to:
I recommend using MP4Box for this. Of course, if you don't specify an
offset (or specify the wrong offset) the first time you mux, you will
need to rewrite the entire file. MP4Box is great for producing compliant
containers, but it requires rewriting or remuxing for damn near everything.

In any case, Matroska will work if it can specify an offset.