[FFmpeg-user] time padding when muxing

[Robin Gareus]

Hi all,

Suppose I have a 1 minute video and a 2 minute audio track.

I want a muxed version:
  20 sec black,  the 1 min video, 40 sec black
along with the 2min audio-track.

Is this possible using a single command?


-=-

Using '-t' and -itsoffset synchronizes A/V correctly. But the first 20
seconds is audio-only and video-window (mplayer or VLC) only opens after
20sec. Also the last video-frame remains frozen for the final 40sec.

-=-

A rawvideo pipeline can do the trick, IFF I query and parse the geometry
and fps of the video first. I'm also uncertain if that'd work x-platform
(windows pipes, anyone?), and besides that it is not very elegant:

( \
  ffmpeg -s $SIZ -f rawvideo -pix_fmt rgb24 -r $FPS   \
                 -i /dev/zero -f rawvideo -t 20 -;    \
  ffmpeg -i $INPUTVIDEO -f rawvideo -pix_fmt rgb24 -; \
  ffmpeg -s $SIZ -f rawvideo -pix_fmt rgb24 -r $FPS   \
                 -i /dev/zero -f rawvideo -t 40 -     \
) \
| ffmpeg -s $SIZ -pix_fmt rgb24 -r $FPS -f rawvideo -i - \
         -i $INPUTAUDIO \
         ..ENCODER..PARAMS..

Is there a better solution?

TIA,
robin