[Libav-user] Getting SPS and PPS-information from x264 encoding

Christian Brümmer christian.bruemmer at gmx.de
Tue May 29 15:26:12 CEST 2012

Am 29.05.2012 14:00, schrieb Christian Brümmer:
> Am 28.05.2012 19:21, schrieb Christian Brümmer:
>> Hi,
>> i encode video frames using a default codec configuration via 
>> avcodec_get_context_defaults3(). That video frames are further used 
>> for rtsp streaming based on live555. For compatibility i need the SPS 
>> and PPS-informations for the rtsp server but i didnt know them (cause 
>> default configurations i cant access).
>> How can i get that infos out of a AVCodecContext after setting to 
>> default values (c-code)?
>> Best regards and thanks for reading,
>> Christian
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>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
> I figured out that those informations typically found in 
> SDP-descriptions. So i tried av_sdp_create which works so far but it 
> has no sprop-parameter-sets :/.
> Cant be that hard - or?
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"Cant be that hard - or? "

Okay now im pretty sure it is:

I read AVCodecContex.extradata contains the informations i need. For 
decoding i used that code -> 
http://cgit.lscube.org/cgit.cgi/feng/tree/src/media/parser/h264.c#n218 - 
in a slightly modified way (replaced glib functions with e.g. libavs 
base64.h). Finally the decoding stuff is running - BUT...

my AVCodecContext.extradata_size == 0 <- what the heck?!? So no data for 
decoding and really no idea left how to get those informations.... WHAA!

I make desperate efforts but i cant get into that...

At least i need another hint. Im not asking for complete solution - its 
enough to know roughly the right way!

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