[Libav-user] H264 stream width and height parameters from live streams

Sampsa Riikonen sampsa.riikonen at iki.fi
Tue Nov 29 14:47:38 EET 2016


Thanks for the reply.

I infer from it, that there is no routine in the api that would populate 
AVCodecContext on the basis of feeding it sps and pps packets only, right..?



On 29.11.2016 13:11, Carl Eugen Hoyos wrote:
> 2016-11-29 12:07 GMT+01:00 Sampsa Riikonen <sampsa.riikonen at iki.fi>:
>> When reading AVPackets from a file, it is straightforward to pass correct
>> parameters to the ffmpeg/vdpau decoder, i. e., we call
>> av_format_find_stream_info
>> and get the relevant data to "AVStream(s)".  Then we do:
>> av_codec_parameters_to_context(AVCodecContext,AVStream.codecpar[AVCodecParameters])
>> That populates correct parameters into AVCodecContext, namely,
>> AVCodecContext->width, height, etc.
>> This works also with "raw" H264 streams (i.e., with ".h264" files), that are
>> not "container" formats, such as matroska, etc..
>> .. so the only conclusion is, that "av_format_find_stream_info" does some
>> kind of sps/pps packet parsing, right?
> It calls libavcodec that does sps/pps parsing (this is the reason libavformat
> depends on libavcodec).
> Carl Eugen
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