[FFmpeg-devel] [PATCH] H.264 timestamps in h264_parser - complete set
Thu Feb 26 00:56:30 CET 2009
On Wed, Feb 25, 2009 at 09:38:17PM +0100, Ivan Schreter wrote:
> Michael Niedermayer wrote:
>> On Tue, Feb 24, 2009 at 09:38:55PM +0100, Ivan Schreter wrote:
>>> Michael Niedermayer wrote:
>>>> On Tue, Feb 24, 2009 at 08:20:53PM +0100, Ivan Schreter wrote
>>>>> I'd propose adding a flag field_picture_flag to AVPacket (and pass it
>>>>> from the parser) to notify the user about field pictures, so it can
>>>>> correctly compute frame rate. What do you think? Or do you have a
>>>>> better idea?
>>>> i dont know, it doesnt seem to be such a big issue to me to have 2*fps
>>> It is for the user. See, I want to convert a H.264 interlaced video to
>>> some other format. So I'd call ffmpeg -i h264.mts -vcodec mpeg2video
>>> -acodec mp2 -f vob h264.vob. What will this do? It will create a vob with
>>> 2*fps and each picture duplicated, which is definitely not what we
>>> want... True, the user could specify -r 25 to force frame rate to 25fps,
>>> but it's not logical. So IMHO we need this. Agreed?
>> yes, there is a problem
> The three attached patches introduce field_frame_flag for
> AVCodecParserContext and AVPacket, use it to correct durations and generate
> field frame flag in H.264. This fixes the problem and interlaced H.264
> movies are now detected at correct fps.
i think (but maybe i miss something) that a solution based on
your "ticks_per_frame" and repeat_pict == 0
could be used to detect fields and this would have the advantage of also
providing a simple way to find the "old time_base" that is
time_base*ticks_per_frame if ticks_per_frame is in AVCodecContext.
> @@ -149,6 +149,17 @@
> * subtitles are correctly displayed after seeking.
> int64_t convergence_duration;
> + /**
> + * Normally, parsed container frames contain a complete video frame.
> + * However, for some formats (e.g., H.264), it is possible that a frame
> + * contains only a field. As fields have just half the duration of normal
> + * frame, frame rate detection would detect 2*fps instead of fps.
> + * By setting this field, frame rate detection will detect correct fps.
> + *
> + * Default 0, set to 1 by parser, if a frame containing single field detected.
> + */
> + int field_frame_flag;
> } AVPacket;
> #define PKT_FLAG_KEY 0x0001
possibly irrelevant now, but this could be done simpler, like PKT_FLAG_KEY
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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