wrong framerate for mkv

[eumagga0x2a]

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.

[mean]

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