[Libav-user] H264 Nal type Unspecified and Undefined filtered?

[Indio]

Hi all,
in order to get nal types can i use codec extradata?
Using buffers like
(https://github.com/FFmpeg/FFmpeg/blob/dfe7e5501d4acf007f66f7ad8606499f7d7dc2cb/libavformat/tests/movenc.c):

static const uint8_t h264_extradata[] = {
0x01, 0x4d, 0x40, 0x1e, 0xff, 0xe1, 0x00, 0x02, 0x67, 0x4d, 0x01,
0x00, 0x02, 0x68, 0xef
};
i could inform the codec to not discard my NAL 30 (or 0) packets and
get it at application level. Is it correct?
Thanks


On Fri, Jun 23, 2017 at 5:19 PM, Indio <ealloradai at gmail.com> wrote:
> Hi all,
> this is my first post in the list and i'm quite new to libav and ffmpeg.
>
> For an experimental project i'm developing an RTSP client and server using
> live555 for server and libav/ffmpeg as client.
> The server treams live video from a webcam.
>
> After each IDR frame we are sending a checksum in the NAL stream using
> unspecified and undefined NAL types. From client side the expected behaviuor
> is to read the checksum un the av_read_frame function.
>
> We tried Nal type 30 but libav discard it with message "Undefined type (30)"
> which happen in the demuxer in the h264_handle_packet function. Looking at
> this function we tried to ne NAL type 0 because the comment says "undefined,
> but pass them through". The problem is that the packet seems to be discarded
> somewhere ad never arrive to be read in the av_read_frame.
>
> So are those NALU filtered? Ho could i embed in the H264 stream a NAL packet
> with user data?
> Thanks in advance
> Indio
>
>
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