[gst-devel] Mixing silence suppressed RTP into a continuous stream

[Marco Ballesio]

Hi,

On Fri, Nov 26, 2010 at 1:45 PM, Joakim Koskela <joakim.koskela at hiit.fi> wrote:
> Hi,
>
> I'm having problems mixing an RTP stream with something else (testing with an
> mp3 file), as the RTP does silence suppression (sending packets only when
> noise is actually made). It seems that mixing is done only when *all* sound
> sources have data to contribute, leading to a chunky output.

it's possible as you don't have any CNG elements in your pipeline.
I've been hacking for a while on it but, unfortunately, there's
nothing really presentable so far. Shame on me :( .

>
> What I would like to have is a continuous output stream into which sound is
> mixed from different sources as it becomes available. Seems like a really
> basic thing, but I somehow couldn't find anything using the search terms I
> thought relevant.

Actually, there's no support for comfort noise in GStreamer. You may
find something in Farsight, but when I last checked it there was
nothing really working. Since I've not tried again for a while maybe
the thing has evolved in the meanwhile.

>
> Any help is appreciated, even just tips on what to look at more closely (the
> adder or the sources) or keywords to search for.

I'm loosely working on the CNG element which may help you with this.
Maybe it'll be possible to completely prototype it during winter
vacations.

Regards

> The pipeline i'm using is:
>
> filesrc location=file.mp3 ! decodebin ! audioconvert  ! audioresample !
> audio/x-raw-int,channels=1,rate=8000 ! adder name=mixer \
> udpsrc port=%s caps="application/x-rtp,media=(string)audio,clock-
> rate=(int)8000,encoding-name=(string)PCMA" ! gstrtpbin ! rtppcmadepay !
> alawdec ! audioconvert ! audioresample ! audio/x-raw-int,channels=1,rate=8000
> ! mixer. \
> mixer. ! audioconvert  ! audioresample ! audio/x-raw-int,channels=1,rate=8000
> ! alawenc ! rtppcmapay ! udpsink host=127.0.0.1 port=8000
>
> br, j
>
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