[FFmpeg-devel] [RFC] Add duration info to AVFrame
stefasab at gmail.com
Fri Jun 1 11:14:04 CEST 2012
On date Thursday 2012-03-08 15:50:21 +0100, Stefano Sabatini encoded:
> the feature would be useful for different purposes, especially for
> normalization/correction timestamp filters (e.g. setpts).
> Different approaches:
> 1. I could export pkt_duration in AVFrame, like it is done with
> pkt_pts, duration is expressed in stream time_base units.
> This alone is not sufficient, because to decode pkt* things we need
> to reference the AVStream, which is not always available.
> 2. I create a duration field in AVFrame, with no specified timebase,
> which is done for passing the duration information between
> different layers (e.g. lavc -> lavfi -> lavc), similar to what we
> did for pts.
> Then I could add a time_base unit in AVFrame, which is used for
> specifying the PTS and duration timebase.
> 3. a combination of 1/2
> Comments are welcome.
Done like 1.
* as mentioned, pkt_pts alone can't be interpreted if there is no
reference to the stream timebase.
* it is not possible to distinguish between duration=0 and
duration=unknown, because 0 == unknown, which depends on how
duration is defined in AVPacket.
Otherwise: would it make sense to change the semantics in AVPacket
* how to get a frame duration from the pkt duration? I assume it is
pkt_duration = frame_duration for video, for audio it could be
FFmpeg = Fierce & Fantastic Mega Power Enhancing Gadget
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