[FFmpeg-user] decode multiple rtp stream for multichannel usage

[s p]

hello,

I am looking to decode (and play) multiple audio (rtp) stream through one
multichannel audio stream

I am able to play one stream with ffplay by simply opening the related .sdp
file

but as I am looking to redirect each stream to a specific audio device, and
that for this I need to create a 6 channel audio stream from those 6 inputs.
(this is well documented here
https://trac.ffmpeg.org/wiki/AudioChannelManipulation )

And as I am not able to decode the stream directly with ffmpeg, it looks
like there is a problem wiith the Header (I don,'t understand why it works
with ffplay then?)

How can I use several instances of ffplay as multiple input for one
instance of ffmpeg ?
or maybe how can I simply decode the rtp stream directly with ffmpeg ?

thank you for your help !