--- On Tue, 13/5/08, Luca Abeni <[EMAIL PROTECTED]> wrote:
> From: Luca Abeni <[EMAIL PROTECTED]>
> Subject: Re: [libav-user] (no subject)
> To: "Libav* user questions and discussions" <[email protected]>
> Date: Tuesday, 13 May, 2008, 7:10 PM
> Hi Gavin,
Thanks for your help thus far.
> Gavin Smith wrote:
> [...]]
> > My goal is to now packetize the H264 data into an RTP
> packet and stream
> > it over a network to another node.
> >
> > From what I read, it appears that FFMPEG already has
> the facilities to
> > do what I want, is that correct?
>
> Yes, it is. You just need to write the H.264 ES to an
> rtp://... URL (using
> the rtp output format).
>
I was able to edit the output_example.c with some mixed success. I was able to
submit MPEG-2 (video) over rtp to a VLC client.
What I actually did was I "tricked" the AVOutputFormat *fmt variable by parsing
fmt = guess_format("mpeg2video", NULL, NULL )
instead of:
fmt = guess_format("mpeg2video", filename, NULL );
This was a quick, easy hack, and I knew it would work because I was sure of the
type of input source. The above worked for "mpeg" (which I presume is mpeg1
format - I couldn't exactly determine this from the VLC client).
All is well, but if I try and submit an h264 ES (video-only) file over rtp and
call:
fmt = guess_format("h264", NULL, NULL )
it appears to find the correct codec, but when I call the open_video function,
it exits because it cannot find the h264 codec when calling
avcodec_find_decoder. I know for a fact that the AVOutputFormat is what I
expect because fmt->video_codec == CODEC_ID_H264.
This isn't the end of the world, because I don't plan on using FFMPEG to
encode...
> >
> > In all honesty, I'm a bit unsure of where to
> start.
> > I've been looking at some doxygen generated
> documentation (in the link below),
> > and cannot quite determine which functions ought to
> be called.
>
> Look at output_example.c to learn how to write a video ES
> into an output
> file. You can start with an avi file, for example. Once you
> have some code
> that successfully writes your H.264 ES in an avi, just
> change the output
> file name to "rtp://<dest addr>:<dest
> port>", and change the output format
> from avi to rtp.
>
> You might want to call avf_sdp_create() to get an SDP
> describing the stream
> (needed to receive it). See ffmpeg.c for details.
Again, I successfully submitted the test clip over the network using RTP. In
addition, I managed to successfully create a valid SDP file using the
avf_sdp_create function.
All that I have transmitted thus far has been the test clip. Now, my end goal
is to use my own encoder and my own h264 encoded data.
I found the AVPacket struct which encapsulate the h264 data to be transmitted.
I understand how to add data to the packet and the rest, but I'm unsure on how
I can parse my h264 data (such that it recognizes NALs and the like) and add it
to the packet.
All I get out of my own encoder is a byte array which is populated every now
and then which [I suspect] contains a couple of h264 es frames.
Suggestions would be appreciated...
Gavin
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