[Libav-user] Format in which ES data is stored in (AVPacket*) pkt->data buffers

[Sergey Fedorov]

By the way, you can find the stream header in AVCodecContext::extradata
after avformat_find_stream_info() call.

2013/6/14 Sergey Fedorov <night.rain.whisper at gmail.com>

> H.264 Video Types<http://msdn.microsoft.com/en-us/library/windows/desktop/dd757808%28v=vs.85%29.aspx>:
>
>
>> 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<http://aviadr1.blogspot.ru/2010/05/h264-extradata-partially-explained-for.html>
>
>
>
> 2013/6/13 Anshul maheshwari <er.anshul.maheshwari at gmail.com>
>
>> 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" <arvind_raman at yahoo.com> 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 AACaudio.
>>>    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
>>> Libav-user at ffmpeg.org
>>> http://ffmpeg.org/mailman/listinfo/libav-user
>>>
>>>
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20130614/d08042f7/attachment.html>