[Libav-user] Can I skip some packets when decoding

Lucas Soltic lucas.soltic at orange.fr
Tue Dec 9 08:46:43 CET 2014

> Le 9 déc. 2014 à 08:12, YIRAN LI <mrfun.china at gmail.com> a écrit :
> Hi, 
> I have a question about read frame,
> Suppose I've just opened a file, so the readpointer is at the beginning of the file.
> Compare these two methods:
> 1. call av_read_frame + avcode_decode_video2 to decode 100 video packets( suppose each packet can decode into a frame)
> 2. call av_read_frame, but only decode the 100th packet (all previous 99 packets are just discarded)
> Will the 100th frame from method 1 and the frame from method 2 have same content, timestamp, etc?
> Thanks


Decoding the 100th packet alone can be equivalent in both situations only if this packet is a keyframe. If not, FFmpeg will need all the packets up to the first preceding key frame in order to be able to give you a frame with correct content. I'm unsure whether other metadata like timestamp depend on the method (although I don't think so).

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