[FFmpeg-user] filter for changing frame rate

[Daniel Oberhoff]

> 
> You can not.

I am curious what exactly the hindrance is. As I understand at least mp4 there is not really a concept of frame rate in the file and in theory every frame can have a different „rate“, defined solely by pts. So in theory pts should be all you need. Where am I going wrong in my understanding, and what exactly are the problems in ffmpeg that would arise?