[FFmpeg-devel] [RFC] SDP Generation

Luca Abeni lucabe72
Mon Jun 11 09:06:54 CEST 2007

Hi Michael,

Michael Niedermayer wrote:
>> Well, the problem is that every single media stream can have a different 
>> destination address. If the "filename" field in AVFormatContext is used 
>> for indicating the destination address, then I need an AVFormatContext 
>> per media stream.
> in what cases are different destination addresses needed/wanted?
The classical example is video streamed to a multicast group, and audio 
streamed to a different multicast group. If an application wants to 
receive both audio and video, it joins both the two groups; if an 
application wants to receive audio only, it only joins the audio group. 
In this way, if multicast is routed in a smart way it is possible to 
reduce the network traffic.

> and why do we need them in a single SDP thingy?
Because both audio and video streams are part of the same session.

> i can also put each stream into a different file, this though does not
> prevent me from putting them in the same file ...
Do you mean, each stream described in a different SDP file? In this 
case, how can a receiving application understand that the streams are 
part of the same session? Or did I misunderstand you here?


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