[FFmpeg-user] Is it possible to just change the fps flags?

[J. Scott Edwards]

Hi Carl,

i don't know that it is a bug at all...  well, maybe that the output
is so terribly pixelated.

i assume that this command:

ffmpeg -i input.avi -r 24 output.avi

is trying to resample the frames so that there are 24 of them in every
second instead of 29.97, but the video is still playing at the same
speed.  I.E. the input file is 10:27 and the output file is 10:27.

But that is not what I want.  I want it to leave the frames exactly
the way they are now but only play 24 of them every second so that the
video runs slower.  I.E. instead of being 10:27 long the video is
13:02.

The command line output is below.

Thanks,
  -scott


$ time ffmpeg -i drag_races.avi -r 24 drag_races-24fps.avi
ffmpeg version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013
the Libav developers
  built on Apr  2 2013 17:00:59 with gcc 4.6.3
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in
a future release. Please use avconv instead.
[mpeg4 @ 0x8d75940] Invalid and inefficient vfw-avi packed B frames detected
Input #0, avi, from 'drag_races.avi':
  Metadata:
    encoder         : MEncoder 2:1.0~rc1-0ubuntu13.2
  Duration: 00:10:27.59, start: 0.000000, bitrate: 6615 kb/s
    Stream #0.0: Video: mpeg4 (Advanced Simple Profile), yuv420p,
720x480 [PAR 1:1 DAR 3:2], PAR 8:9 DAR 4:3, 29.97 tbr, 29.97 tbn,
29.97 tbc
[buffer @ 0x8d74f60] w:720 h:480 pixfmt:yuv420p
Output #0, avi, to 'drag_races-24fps.avi':
  Metadata:
    ISFT            : Lavf53.21.1
    Stream #0.0: Video: mpeg4, yuv420p, 720x480 [PAR 8:9 DAR 4:3],
q=2-31, 200 kb/s, 24 tbn, 24 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press ctrl-c to stop encoding
[mpeg4 @ 0x8d75940] Invalid and inefficient vfw-avi packed B frames detected
frame=15062 fps=223 q=31.0 Lsize=   72816kB time=627.62 bitrate=
950.4kbits/s dup=0 drop=3747
video:72450kB audio:0kB global headers:0kB muxing overhead 0.505254%

real    1m8.118s
user    1m0.412s
sys    0m5.992s

On Sat, Jul 6, 2013 at 10:57 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> J. Scott Edwards <lost.alternative <at> gmail.com> writes:
>
>> i have several videos that were created from film, one film
>> frame to one video frame, so it plays too fast (29.97 fps).
>
> Could you elaborate / command line and complete, uncut
> console output missing.
> (This may be a serious bug but I need more information to be
> able to reproduce.)
>
>>  ffmpeg -i input.avi -r 24 output.avi
>
> $ ffmpeg -i input.avi -vf fps=24000/1001 -qscale 2 out.avi
>
> Carl Eugen
>
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