[libav-api] Packaging Raw H264/AAC frames into FLV/RTMP Stream

Evgeny Yakimov john.yakimov at gmail.com
Mon Oct 3 15:16:34 CEST 2011


Hello Lu

I am using the same h264 raw frames (in this case from x264) both in my app
and the ones that avconv reads from using the command:
avconv -i /mnt/videos/raw.h264 -vcodec copy -f flv test.flv

I have just created two flv files, one from my own code, and the other from
the command above, which both use the same raw frames.

I then wrote a quick program to read and dump the frames from the flv files
so that I can compare them:
http://pastebin.com/GAGNUT3S

It seems that the first frame is much bigger, and every key frame is also at
least 2 bytes bigger, every non key frame although the same size has been
modified in byte 3 and 4. So it seems that avconv modifies these frames
before writing them into the flv container.

I have uploaded the entire program that I use to create my flv here (argv[1]
points to a source file of raw 422 frames which are converted to 420 prior
to being sent to x264)
http://pastebin.com/wMGe554k
(please ignore the audio for the time being)

Any Idea on how avformat modifies these frames?

Regards,
Evgeny
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