[gst-devel] comfort noise generation bin

[Marco Ballesio]

Hi all and especially Farsight developers,

checking on the Farsight todo
list<http://farsight.freedesktop.org/wiki/Farsight2Todo>I see
something is being cooked about CN generation.
On Farsight sources I can see a basic handling of CN sending, but not that
much about receiving it.

As it appears CN generation in the receive side is the trickiest part, I
wanted to know how it's planned to deal with it. In example, for g729
packets it's possible to receive only a SID frame and then nothing more
until the next talkspurt: because of DTX it's not possible to give any
direct relations between input packets and output uncompressed time length.
RFC3389 also defines some ways to adjust the noise level before the next
talkspurt but, again, DTX makes it hard to deal with CN by using a
traditional GStreamer decoder.

If nothing is already available, I was thinking about a generic support bin
to be controlled from the speech codecs or depayloaders. The bin structure
may be sketched with an audio source generating a coloured noise with the
pole-only spectral description obtained from the silence encoder, connected
togehter with the decoder to an input selector. The latter would be simply
controlled from the depayloader (or decoder) when e.g. a SID/talkspurt start
has been received.

Are there any other/better ideas (being) implemented?
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