[FFmpeg-user] Timestamp for variable frame rate (VFR ) video

Wolfgang Hugemann auto at hugemann.de
Mon Sep 24 19:02:59 EEST 2018

> I will inform you about the results.

In short: ffmpeg and ffprobe perform very well on VFR video. The
presentation time stamp %{pts} is the right information to display by
drawtext if you need to know the exact time for a certain frame.

It's a pity that you cannot format the float number displayed; it seems
to be set to 6 decimal places.

In regard to the several mobile phone cameras we have tested, we found
that all of them (including an iPhone) recorded VFR video, but the
framerate was not very variable: It lies between 29-something and 30
fps. Only the iPhone dropped down to 28 fps every few seconds, obviously
being occupied by some other task.

In the case of the VFR video that started this discussion, the framerate
allegedly varied between 15 and 30 fps, but this was due to a single
frame drop at its very beginning, the rest of the time it behaved like
any other mobile phone.

The variations in the vehicle movement seem to have to be blamed on the
supervision cam.

Thank you for your support!

Wolfgang Hugemann

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