[Ffmpeg-devel] Frame rates and time_base
Sat May 7 07:04:58 CEST 2005
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. On the other hand
it's impossible to convert DTS to PTS without knowing specifics of the
The situation would be reversed if you store frames in display order
rather than decode order, but that's just stupid..
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