[Live-devel] Mplayer and SDP

emanuele bottegoni emanuele.b at automaonline.com
Wed Oct 1 02:27:32 PDT 2008

Hello developers!

I need to solve an issue regarding the local playing of both audio and
video streams.
I have a an audio/video Intercom (using SIP/SDP protocols) that is
connected in P2P to a lightweight SIP UA (PJSIP).
When the communication starts I can play the H264 video launching:

mplayer -fps 10 sdp:///home/ema/123-pj.sdp 

with the following sdp file:


o=- 3429958819 3429958820 IN IP4


c=IN IP4

t=0 0

m=video 1234 RTP/AVP 126 125

a=rtpmap:126 H264/90000

a=fmtp:126 profile-level-id=42801E; packetization-mode=1

a=rtpmap:125 H264/90000

a=fmtp:125 profile-level-id=42801E; packetization-mode=0


Now I want Mplayer plays also the ulaw (or alaw) audio stream coming in
from the intercom.
I've added some lines to the mentioned sdp file, but I get always the same
The lines added are:

m=audio 4002 RTP/AVP 0 101

a=rtcp:4003 IN IP4

a=rtpmap:0 PCMU/8000


a=rtpmap:101 telephone-event/8000

and the log error is:

Failed to initiate "audio/PCMU" RTP subsession: getsockname() error: Bad
file descriptor

I've tried some modifications of the audio lines but I get always the same

Anyone can suggest me the correct solution?



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