[Ffmpeg-devel] Frame rates and time_base

Rich Felker dalias
Sat May 7 19:25:45 CEST 2005

On Sat, May 07, 2005 at 06:17:00PM +0200, M?ns Rullg?rd wrote:
> >> >> If PTS and DTS are different for an encoded frame, there is no way to
> >> >> determine one from the other.  While decoding a sequence of frames, it
> >> >> is of course possible to determine any PTS, given the PTS of one of
> >> >> the frames.
> >> >
> >> > Huh? Given a sequence of frames and their order, it's possible (and
> >> > easy -- see the NUT spec) to convert PTS to DTS.
> >> 
> >> The NUT spec is irrelevant.  Most containers don't give the display
> >> order explicitly.
> >
> > NUT does not either. RMFM (read my fucking mail) and RTFNS (nut spec)!
> So what on earth does NUT have to do with the issue?

Nothing except that the NUT spec documents the alogorithm for
PTS+order->DTS conversion, which works for all containers with decode
ordering, not just NUT.

> > The point is that, given the frames in DECODE ORDER (which any sane
> > container uses) and given PTS for each frame, you can reconstruct DTS.
> I've never said you can't.  What I said, was that there is no way of
> converting between PTS and DTS, without a sequence of frames.

OK, this is obviously true.

> > Obviously you cannot go the other way around (which is what you're
> > arguing and what I already said) unless the frames are stored in
> > display order, which, I repeat, is stupid.
> So why are you arguing, if you agree with what I've said?

I could have asked the same of you.. :)


More information about the ffmpeg-devel mailing list