[FFmpeg-devel] Reordering of GOP Frames

[QuickTime]

Dear:

The simplest answer :
 the I/P will be cached until the next I/P frame reaches when "has_b_frame
"is true


On 9/13/07, Axel Gallus <uh5d at rz.uni-karlsruhe.de> wrote:
>
> Can please someone comment on my thoughts...
>
> Lets say we have the following display sequence: I B B P
> Where both B's depend on the following P.
> Therefore the above sequence has be arranged to I P B B in the videofile.
>
> 1.)    av_read_frame() first reads I in AVPacket struct.
>        avcodec_decode_frame() decodes AVPacket and has complete frame,
> because I = Keyframe
>        frame gets converted and shown ( e.g. via sws_scale() )
>
> 2.)    av_read_frame() reads P in AVPacket struct.
>        avcodec_decode_frame() decodes AVPacket and signals no frame,
> because it must'nt show it at this time.
>        So the P-Frame just gets buffered
>
> 3.)    av_read_frame() reads B in AVPacket struct.
>        avcodec_decode_frame() decodes AVPacket and has complete frame,
> because P frame already has been decoded
>        frame gets converted and shown ( e.g. via sws_scale() )
>
> 4.)    av_read_frame() reads B in AVPacket struct.
>        avcodec_decode_frame() decodes AVPacket and has complete frame,
> because P frame already has been decoded
>        frame gets converted and shown ( e.g. via sws_scale() )
>
> 5.)    av_read_frame() now reads P in AVPacket struct. !??!
>        avcodec_decode_frame() has complete frame, because P frame already
> has been decoded and buffered
>        frame gets converted and shown ( e.g. via sws_scale() )
>
>
> Are those thought right 5 reads for 4 frames?
> If not, when does the P-frame get shown?
>
> Regards
>
> A.Gallus
>
>
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>



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