[Live-devel] mp3 sdp question

[Ross Finlayson]

>I'd like to stream mp3 with livemedia, but I have a question about 
>the sdp string. I want to send information such as sampling 
>frequency and channels number to the client so that the client can 
>work correctly, but the mpeg1or2audiortpsink doesn't have parameters 
>to pass these information, how can I put these into the sdp?

You can't - and you don't need to.  For MPEG-1 or 2 audio (which 
includes 'MP3'), the audio frames are 'self-describing', which means 
that the sampling frequency and number of channels are part of the 
audio frame data (specifically, the MPEG audio header within the 
frame).  Therefore, these parameters are not transmitted separately 
within the RTP packets, or in the SDP description.

>  Or the client can get these information from the frames data by itself?

Yes, see above.

Note that our software can already be used to stream MP3 audio (using 
"live555MediaServer" or "testOnDemandRTSPServer" for unicast 
transmission, or "testMP3Streamer" for multicast transmission).  You 
don't need to write any more code to do this!
-- 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/