[FFmpeg-user] stream mapping seems to work, but doesn't

[Nicolas George]

Le sextidi 6 prairial, an CCXXIV, sean darcy a écrit :
> >But no joy:
> >
> >ffprobe -i out5A-x.VOB
> >..............
> >Input #0, mpeg, from 'out5A-x.VOB':
> >  Duration: 00:25:50.02, start: 0.500000, bitrate: 5516 kb/s
> >    Stream #0:0[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 224 kb/s
> >    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv,
> >smpte170m), 720x480 [SAR 8:9 DAR 4:3], max. 8500 kb/s, 29.97 fps, 29.97
> >tbr, 90k tbn, 59.94 tbc

There is no order of streams in VOB containers. Not the ones you read, and
not the ones you create.

> Or am I going at this all wrong? I have a set of VOB's that have random
> steam orders. I want an mp4.
> 
> fmpeg -safe 0 -f concat -i mylist.txt \
>  -c:v:0 libx264 -c:a:0 aac  out.mp4
> 
> where mylist.txt has the VOB's.

IIRC, you forgot to tell us you were using the concat demuxer. There is a
stream order in the concat demuxer, it is the order of the streams in all
the files, and it must be the same. Obviously, it does not work for VOB
files, but there is a countermeasure:

https://www.ffmpeg.org/ffmpeg-formats.html#concat

Search "This is especially useful for MPEG-PS (VOB) files, where the order
of the streams is not reliable.".

Regards,

-- 
  Nicolas George