Author Topic: wrong framerate for mkv  (Read 218 times)

eumagga0x2a

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wrong framerate for mkv
« on: April 07, 2017, 10:07:37 AM »
Yes, now the values calculated by Avidemux and ffprobe match, thanks (the same logic should apply to the mp4 demuxer, shouldn't it?).

The 1000 fps issue is a different thing. I was wrong attributing it to the copy mode, it is enough to specify MKV as muxer. The bad: it is not enough to remux the video as mp4 to restore the old fps, both Avidemux and ffmpeg calculate different, deviating values. My test sample: a video with the vimeo-id 67995158 (1080p at 25fps) A supercell near Booker, Texas.

STR:

  • Load the sample video, check the properties
  • Save in copy mode or reencode with codecs compatible with the MP4 muxer as a MKV
  • Load the resulting .mkv, check the properties
  • Save this MKV in copy mode as MP4
  • Load the resulting .mp4, check the properties
  • Run ffprobe with the .mp4 as argument

Actual Results:

The fps value is displayed as 1000.000 fps in Step 3, as 24.991 fps in Step 5 and as 25.03 in Step 6.
« Last Edit: April 07, 2017, 02:55:28 PM by mean »

mean

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Re: wrong framerate for mkv
« Reply #1 on: April 07, 2017, 02:56:37 PM »
It's caused by the new ffmpeg
Since mkv has a built-in accuracy of 1ms, they force the timebase to be in ms, hence screwing avidemux which tries
to provide a rational