[FFmpeg-user] ffmpeg and aspect ratio changes with different container formats.

[Toerless Eckert]

On Wed, Nov 16, 2016 at 11:03:08AM +0100, Carl Eugen Hoyos wrote:
> 2016-11-16 3:53 GMT+01:00 Toerless Eckert <tte at cs.fau.de>:
> 
> > A) mp4 container _should_ be able to carry per-frame AR information,
> 
> (How would that work?)
> Please provide such a sample.

See old thread: 

http://lists.mplayerhq.hu/pipermail/mencoder-users/2010-September/012189.html

Sample at: https://trac.ffmpeg.org/attachment/ticket/5959/ar-change.mpg

Retested:

Encoder: ffmpeg = 3.2.git
Players: ffplay = 3.2.git, mplayer = 1.2.1, vlc = 2.2.4, kodi = 16.1

ffmpeg -i ar-change.mpg -vcodec mpeg4 ar-change-mpeg4.{ts,avi,mp4,mkv}
ffmpeg -i ar-change.mpg -vcodec libx264 ar-change-h264.{ts,avi,mp4,mkv}

all players correctly process AR change for mpeg4 or h264 codec with ts mux

Only mplayer correctly processes AR change for mpeg4 or h264 codec, avi mux

Q: Is this something that would have to be changed asking all "real" players 
(VLC, kodi), or would those players get working AR change from ffmpeg if this
was fixed somewhere in ffmpeg/ffplay ?

No player shows AR change for mpeg4 or h264 codec, mp4 or mkv mux

Q: Is this an ffmpeg encoding bug, or do these mux'es really suck, aka:
they do not support aspect ratio changes ? (And that would suck because
even avi is supporting it seemingly).

I primarily wonder what mux to use: Everybody told me mp4 and mkv are so great,
and avi is so obsolete. Doesn't match what i can do with them. At this point,
ts seems to be my best choice.

Also see https://trac.ffmpeg.org/attachment/ticket/5959, with h265 nothing wrt. AR
change works, but thats to be expected (still new code).

Cheers
    Toerless