> From: Sergey Fedorov <[email protected]> >By the way, you can find the stream header in AVCodecContext::extradata after >avformat_find_stream_info() call.
Thanks that was a life saver tip. I could review the code and see how extradata was being processed. For everyone's benefit I am copying the link to the blog post H.264 extradata (partially) explained for dummies http://aviadr1.blogspot.in/2010/05/h264-extradata-partially-explained-for.html ~ Arvind >2013/6/14 Sergey Fedorov <[email protected]> > >H.264 Video Types: >> >>The MP4 container format stores H.264 data without start codes. Instead, each >>NALU is prefixed by a length field, which gives the length of the NALU in bytes. The size of the length field can vary, but is typically 1, 2, or 4 bytes. >> >>See also: H.264 extradata (partially) explained - for dummies >> >> >> >>2013/6/13 Anshul maheshwari <[email protected]> >> >>U can try using gdb, put a brk point on above line u provided, >>>Print the pkt, >>>If trouble using gdb, reply me I wud do fr u! >>>It was never required to me! >>>Anshul >>>On Jun 13, 2013 10:16 PM, "Arvind Raman" <[email protected]> wrote: >>> >>>Question - What is the format in which audio / video ES data is stored in >>>(AVPacket*) pkt->data? I am trying to demux and decode AV data from a MP4 >>>file using libavformat and libavcodec. >>>> >>>> >>>>More details >>>> 1. Using the sample application demuxing.c >>>>(http://www.ffmpeg.org/doxygen/trunk/demuxing_8c_source.html) I tried >>>>demuxing and decoding a MP4 file containing H.264 video and AAC audio. >>>> 2. While the sample application worked fine, I wasn't able to interpret >>>>the content in the pkt.data buffer (line #66 in the above file). Since the >>>>video was H.264 I was hoping to see familiar "nal_unit_type" but I don't >>>>think I saw that for the stream I was trying to decode. If I remember the >>>>data correctly the first 4 bytes in the pkt.data buffer were "0x00 0x00 >>>>0x02 0x72" >>>>I haven't spent much time figuring this out yet but searching on the >>>>Internet / forum didn't help. I intend to dig deeper tomorrow, but just >>>>wanted to check if indeed ES was being passed in the pkt.data buffers in a >>>>special way. >>>> >>>> >>>>Appreciate any points that you can provide. >>>> >>>> >>>>Best regards >>>>Arvind >>>> >>>> >>>>_______________________________________________ >>>>Libav-user mailing list >>>>[email protected] >>>>http://ffmpeg.org/mailman/listinfo/libav-user >>>> >>>> >>>_______________________________________________ >>>Libav-user mailing list >>>[email protected] >>>http://ffmpeg.org/mailman/listinfo/libav-user >>> >>> >> > >_______________________________________________ >Libav-user mailing list >[email protected] >http://ffmpeg.org/mailman/listinfo/libav-user > > > _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
