Am 31.05.2012 15:51, schrieb Christian Brümmer:
Am 30.05.2012 12:44, schrieb Christian Brümmer:
Am 30.05.2012 04:07, schrieb Kalileo:
On May 29, 2012, at 20:26 , Christian Brümmer wrote:
"Cant be that hard - or?"
Okay now im pretty sure it is:
I read AVCodecContex.extradata contains the informations i need. For decoding i
used that code ->
http://cgit.lscube.org/cgit.cgi/feng/tree/src/media/parser/h264.c#n218 - in a
slightly modified way (replaced glib functions with e.g. libavs base64.h). Finally
the decoding stuff is running - BUT...
my AVCodecContext.extradata_size == 0<- what the heck?!? So no data for
decoding and really no idea left how to get those informations.... WHAA!
I make desperate efforts but i cant get into that...
At least i need another hint. Im not asking for complete solution - its enough
to know roughly the right way!
> From what I think I understood extradata contains what you expect when your
source is a video format with a global header.
What's the source format you use for your tests?
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I create dummy images (should be replaced later on) and encoding them
to x264 frames. Further i stream those images via rtsp which is
working on VLC but not on android and i thinks its a stream
configuration problem.
When should extradata be filled? In my text a dont encode a frame
before i try to get the sps pps infos out of extradata. I may have to
call a special function or encode a frame or header before?
So my source format is:
codec = avcodec_find_encoder(c->codec_id);
if(!codec)
{
std::cout << "Codec not found." << std::endl;
std::cin.get();std::cin.get();exit(1);
}
*if(avcodec_get_context_defaults3 (c, codec) < 0) // cause i dont
know a working x264 configuration without deprecated flags *
{
std::cout << "Cannot get default codec context! \n" << std::endl;
std::cin.get();
exit(1);
}
and
codec = stream->codec;
codec->codec_id = codecID;
codec->codec_type = AVMEDIA_TYPE_VIDEO;
codec->bit_rate = mParameters.mBitRate;
codec->width = mParameters.mWidth;
codec->height = mParameters.mHeight;
codec->time_base.den = mParameters.mFrameRate;
codec->time_base.num = 1;
codec->gop_size = mParameters.mFrameRate;
codec->pix_fmt = PIXEL_FORMAT;
codec->b_frame_strategy = 0;
codec->level = 12;
if(codec->codec_id == CODEC_ID_MPEG2VIDEO)
codec->max_b_frames = 2; // for testing, B frames
if(codec->codec_id == CODEC_ID_MPEG1VIDEO)
codec->mb_decision = 2;
if(context->oformat->flags & AVFMT_GLOBALHEADER)
codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
where mParamters are:
imLiveStreamParameters param;
param.mBitRate = 4000;
param.mCodec = "x264";
param.mFrameRate = 24;
param.mHeight = 240;
param.mWidth = 320;
Thank you for your reply!
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I figured out that if i add c->flags |= CODEC_FLAG_GLOBAL_HEADER; for
my video codec configuration AVCodecContext.extradata.size is bigger
than 0.
Whats a reason for dont using global headers?
Further i tried the av_sdp_create function again and now i get a
string containing "sprop-parameter-sets". My rtsp server accept the
sdp string but the vlc cant play my stream. But i will ask the live555
mailing list for that!
Are there other aspects i have to consider using global header with
x264 encoding (other configurations)?
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I finally got it. The created sdp-line is working as expected. I had to
create a substring and only parsing the "bytestream" of the
sprop-parameter-sets without the qualifier "sprop-parameter-sets=". But
thats nothing about libav.
Thanks for reading,
best regards,
Christian
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