[vlc-devel] Re: Audio Mixing Plugin

Christophe Massiot massiot at via.ecp.fr
Thu Oct 5 00:13:48 CEST 2006

At 12:29 -0500 2/10/06, Ehren Jarosek wrote:
>I am looking to develop an audio mixing plugin associated with mosaic
>feeds which would allow all audio streams from the mosaic to be mixed
>together into a single audio stream to be sent along with the video
>mosaic stream.
>The reason we would want this (vs sending the audio streams as
>selectable) would be for video conference applications (so that we could
>watch a feed where people are talking to each other as a single stream).
>Anyway, I have not been able to determine a way of doing this with the
>existing plugins and was wondering if I could get some guidance as to
>where to begin.  I have looked over the API documentation for sound
>plugins and am not sure what type I would need to develop.  From
>watching the verbose debug logs I can see that the existing mixer
>plugins seem to be used exclusively when outputting sound to a device
>(sound card) and are applied to a single audio feed.  Where would I need
>to insert the mix login into the plugin path and what type of plugin
>should it be?

Indeed you need to develop a new plug-in which would work like the 
bridge-in and bridge-out modules. A "mixer-out" pseudo-audio_output 
module to place the decoded sound of each input instance in a global 
variable, and a "mixer-in" sout_stream module to do the actual mixing 
and encoding, and place the result in a new elementary stream of the 
main input chain, like the bridge-in module does for every audio.

Christophe Massiot.

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