[Libav-user] Encoding with variable frame rate

[Carl Eugen Hoyos]

Robert Krüger <krueger at ...> writes:

> >> > FFmpeg's mov muxer does not support vfr.
> >>
> >> Do you know what exactly is missing?
> >
> > No, but it was discussed recently on irc.

(Maybe not recently or not on irc, sorry.)

> OK, I am asking because in the code there is neither 
> a comment regarding that nor is it obvious that a 
> frame rate is used anywhere with the exception of 
> timecode tracks where it is needed for obvious 
> reasons and in mov_write_uuidprof_tag, which is 
> only used in PSP mode and the Quicktime spec AFAIK 
> offers no means of specifying a constant frame 
> rate explicitly.

The point is that it will not try to write vfr files 
because the relevant flag is not set.
(iiuc)

> It will just result in a time-to-sample table that 
> looks differently if it is constant. But, of course, 
> there may be not so obvious places in the code, 
> where constant frame rate is assumed and for people 
> considering working on the mov muxer, this would be 
> valuable information. That's why I am asking. Is 
> IRC traffic archived publicly somewhere?

http://ffmpeg.org/pipermail/ffmpeg-devel-irc/
But I searched hard and couldn't find the (short) 
discussion I thought to remember ;-(

This might help you:
http://git.videolan.org/?p=ffmpeg.git;a=commit;h=91360ce

Carl Eugen