On 6/20/2013 4:51 PM, Alex Cohn wrote:
On 20 Jun 2013 11:13, "Dragos Iordache" <[email protected]
<mailto:[email protected]>> wrote:
>
> Hi again,
>
> So I tested some more and the stream works ok with .\ffmpeg.exe -i
.\test.h264 -c:v copy -f flv rtmp://live.justin.tv/app/live_****
<http://live.justin.tv/app/live_****>
> But the stream does not work with my implementation using libffmpeg.
>
> I tried different methods for sending the stream with libffmpeg but
none worked ok. What I do now:
>
> -create an oformat of flv
> -create a context for flv and filename=rtmp:/...
> -initialize a stream of h264 codec
> -write header
> -encode using stagefright
> -create a packet
> -write the packet
>
> The test.h264 in the ffmpeg line is created using this method and
filename is set to "test.h264" and not a rtmp server, so I think this
is ok.
>
> The captured frame data differs slightly between the command I run
with ffmpeg and my code using libffmpeg. One of the diferences if that
the NAL header "00 00 00 01" is not like this in the ffmpeg method.
Absolutely. FLV uses the AVCC format to store h264 NALUs. See for
example an excellent explanation at
http://livertmpjavapublisher.blogspot.co.il/2011/06/h264-avcvideopacket.html.
> What do you think is not right?
Stagefright encoder produces packets in annex-b format. It could be
enough to change their headers to AVCC format to make your rtmp happy.
> Thanks for your help.
>
> Dragos
Regards,
Alex
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Yes,
Take the annex-b stream nals, typically sps,pps,idr,slice,slice......
extract the sps and pps from the stream and create the flv avc config
packet. For the rest of the frames, the idr and slices. Swap the marker
bytes for size values, pre-pend pts offset and then wrap with the AMF
flv audio block header.
I often refer to this java class which transcodes annex-b into AMF flash
live streams for the red5 server.
http://code.google.com/p/comserver/source/browse/trunk/plugins/shoutcast/src/org/red5/server/plugin/shoutcast/marshal/transpose/VideoFramer.java#421
Although the raw frame parsing code is old, the beef of the critical
packets and format of the AMF payload is still valid.
If writing a file, those AMF packets will need to be wrapped with the
FLV context tag header and trailing size marker, but for rtmp they are
ready to fly..
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