[FFmpeg-devel] [PATCH] RTSP multicast fix

Thijs Vermeir thijsvermeir
Thu Jul 12 21:25:17 CEST 2007


Hi

On Thu Jul 12 16:35:55 CEST 2007, Michael Niedermayer wrote :

>> Index: libavformat/rtsp.c
>> >===================================================================
>> --- libavformat/rtsp.c	(revision 9556)
>> +++ libavformat/rtsp.c	(working copy)
>> @@ -967,7 +967,7 @@
>>                  av_strlcat(transport, ",", sizeof(transport));
>>              snprintf(transport + strlen(transport),
>>                       sizeof(transport) - strlen(transport) - 1,
>> -                     "RTP/AVP/UDP;multicast");
>> +                     "RTP/AVP;multicast");
>>          }
>
>why is this needed?

in the rfc that describes this SDP protocol [1] RTP/AVP/UDP is only
for unicast streams, RTP/AVP must be used for multicast streams. (also
in the examples in the RFC for RTSP [2] page 66)

> ...
> ttl looks unused after this change
Now it usses the ttl value announced in the SDP messages.
> also the indention doesnt really look good
fixed in this patch

> also which rtsp stream needs these changes?
Now, the implementation is just wrong... it asks the stream from the
IP from the encoder and from the wrong port. It needs to be the
multicast adress announced in the SDP message. ( same for the port)
So, no rtsp multicast encoder will work corretly with the old code.
This patch allows (tested) the Axis encoders [3] (and others...) to
stream multicast streams to the ffmpeg libs.

Gr,
Thijs


[1] RFC 2327 : http://www.faqs.org/rfcs/rfc2327.html (  Media
Announcements, 3rd point)
[2] RFC 2326 : http://www.ietf.org/rfc/rfc2326.txt
[3] http://www.axis.com/products/video/video_server/index.htm
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