Subject: [MMUSIC] Re: [AVT] RTSP and negotiation about Codec's capabilities

From: Magnus Westerlund <[email-masked]>
Date: Wed, 16 Feb 2005 09:37:03 +0100

Hi,

This discussion belongs to the MMUSIC list, not AVT. Anyone responding 
to this email, please remove AVT.

[email-masked] wrote:
> Hi, 
>         Could some please clarify: 
>         With RTSP as the control protocol for a streamed multimedia session, how does the Server determine if the Player has the capability to decode the content it receives? In other words, how does the Player specify the capabilities of the codecs available with it? 
>         An example might clarify the information I am looking for. Suppose the streamed content contains a MPEG-4 video bitstream (Simple Profile and level L3). Now the Server needs to check if the MPEG-4 video decoder available with the Player has the capability to decode this bitstream or not. Conceptually, it needs to query the Profile and Level supported by the MPEG-4 video decoder, and that can help it decide whether the Player can decode this particular MPEG-4 video bitstream or not. 
>         How is this handled in a generic sense (the decoder could be a MP3 decoder, MPEG-4 video decoder, AAC decoder ...) ? Is there standard set of parameters about each codec’s capability that the Player would inform the Server ? 

RTSP doesn't have any support for capability exchange. However this is 
resolved in for example 3GPP PSS, where it is specified that one can 
include UAProf profiles in the DESCRIBE request. See 3GPP TS 26.234 for 
the specification.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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