[Ffmpeg-devel] Frame rates and time_base

[Måns Rullgård]

Rich Felker <dalias at aerifal.cx> writes:

> On Sat, May 07, 2005 at 11:33:58AM +0200, M?ns Rullg?rd wrote:
>> Rich Felker <dalias at aerifal.cx> writes:
>> 
>> > On Sat, May 07, 2005 at 12:00:46AM +0200, M?ns Rullg?rd wrote:
>> >> Bill May <wmay at cisco.com> writes:
>> >> 
>> >> > M?ns Rullg?rd wrote:
>> >> >> OK, I'll try to rephrase it.  Where does libavcodec get the values it
>> >> >> puts in AVFrame.pts?  If the demuxer supplies a pts with a frame, I'd
>> >> >> like that pts to appear in the corresponding AVFrame.  How do I tell
>> >> >> libavcodec about the pts of the encoded frames I'm feeding it?
>> >> >
>> >> > I'd like to know if:
>> >> >
>> >> > for the encoder, if it is possible to put a DTS, then get the PTS
>> >> > of the returned frame ?  (x264 has this).
>> >> >
>> >> > for the decoder, pass in a PTS, and get a DTS from the decoded frame.
>> >> 
>> >> 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?

> 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.

> 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?

-- 
M?ns Rullg?rd
mru at inprovide.com