[FFmpeg-user] FFmpeg accuracy issues.

Roger Pack rogerdpack2 at gmail.com
Tue Aug 7 23:04:38 CEST 2012

> *    Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p,
> 480x360, 733 kb/s, 24.46 fps, 29.97 tbr, 600 tbn, 1200 tbc*
> ...
> As you probably noticed, the video file duration is 00:00:40.38. Using the
> following command, I ripped it's audio track:
> ...
> '*ffmpeg -i foo.mov foo.wav*'
> *size=    3482kB time=00:00:40.42 bitrate= 705.6kbits/s    *

(basically it went from 40.38 to 40.42)
One interesting note is that 0.04 is "about" one frame at 29.97 fps,
which the input "pretends to be" I wonder if there is an off by one
issue or something...

Actually just doing a test like this (converting mp3 to mp3):

$ ffmpeg -i yo.mp3 -vn -acodec libmp3lame yo2.mp3

over and over yields durations like:
yo.mp3 (start): 50.25 seconds
yo2.mp3 : 00:00:53.28
yo3.mp3 : 00:00:53.30
yo4.mp3 : 00:00:53.32

Something doesn't seem quite right here, the same audio file appears
to be getting longer and longer...


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