[FFmpeg-user] Wrong input framerate detected

Mike Scheutzow mike.scheutzow at alcatel-lucent.com
Fri May 11 14:54:52 CEST 2012

Brendan Brewster wrote:
> It seems that ffmpeg is incorrectly detecting the input framerate of a
> video I have.
> ...
> Input #0, mpeg, from
> 'concat:VTS_02_1.VOB|VTS_02_2.VOB|VTS_02_3.VOB|VTS_02_4.VOB|VTS_02_5.VOB':
>   Duration: 01:40:30.97, start: 0.041500, bitrate: 6199 kb/s
>     Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [SAR
> 32:27 DAR 16:9], 9800 kb/s, 26.69 fps, 59.94 tbr, 90k tbn, 59.94 tbc

Mediainfo does not tell the whole story, and is not doing the same 
calculation that ffmpeg does.

For ffmpeg, I believe that the 'fps' value is the average framerate of 
the beginning of the video. If ffmpeg can't get the info from the file 
header, ffmpeg evaluates a few hundred frames to calculate this.

If the movie is a mix of 23.97 frame/sec material and 29.97 frame/sec 
material, 26.69 is a reasonable number for an average value.

Look up the word "telecine" if you care to understand this better.

Mike Scheutzow

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