[FFmpeg-user] 1080i AVC-I 100 frame rate conversion

[Carl Eugen Hoyos]

Am Mo., 29. März 2021 um 10:44 Uhr schrieb Bruce Roberts <roberb04 at gmail.com>:

> The background to this is that I have to transcode 23.976fps and 29.97fps
> content for a VOD platform that will only accept 25fps. Their
> documentation says that *prefer *speed change when going from 23.976fps
> or 24fps to 25fps but that they also require motion compensation.

I don't think this makes sense:
Either you are showing content where the speed (and duration) can be
changed but this does not matter - such content is rare but likely
exists, in this case you don't need any motion compensation at all.
Or you don't want to change the speed (and duration) of your video,
then you can either drop / duplicate frames or use motion compensation:
One of these techniques is very fast, the other extremely slow...

To shorten this discussion a little:
If you go from 24000/1001 or 24 to 25, it should be acceptable to
change the speed, just force an input framerate of 25 and change
the audio pitch.
If your input is 30000/1001, you either have to drop frames or
use some kind of motion compensation.

Carl Eugen