[FFmpeg-trac] #2658(avformat:new): Written mp4 with h264/AAC doesnt use fps as video timebase (discrepancy with libav)
FFmpeg
trac at avcodec.org
Sat Feb 1 08:58:05 CET 2014
#2658: Written mp4 with h264/AAC doesnt use fps as video timebase (discrepancy
with libav)
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Reporter: Lastique | Owner:
Type: defect | Status: new
Priority: normal | Component: avformat
Version: 1.2.1 | Resolution:
Keywords: mov, libav | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by Lastique):
> To ensure the timebase is precisse enough to allow precissely specifying
timestamps of frames. Also some containers like mpeg-ps/ts use a fixed
90khz timebase that cannot be changed.
I think, that's the container details libavformat is supposed to abstract
away from the user. Timestamp conversion is performed in any case - either
inside the muxer or in the user's code, when it discovers what time base
the muxer wants. My point is that the muxer is a better place for the
conversion since it eases life for the user and makes libavformat
interface more uniform across different containers.
You could report the "desired" time base through some new interface before
the user opens the context so that when the user has the liberty of
choosing his internal timestamp granularity he can use the time base that
is best for the container. In this case the muxer wouldn't have to perform
the conversion.
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Ticket URL: <https://trac.ffmpeg.org/ticket/2658#comment:6>
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