[maemo-developers] Using available DSP tasks

[From: Daniel Charles]

Hi,

See the merged pipeline below

On Dec 31, 2007 7:49 AM, Simon Pickering <S.G.Pickering at bath.ac.uk> wrote:
>
> > Thanks for your explanation.
>
> np
>
> > After having read the basic Gstreamer documentation, I understand
> > better the sink pad concept of the mp3 task. In the application I am
> > thinking about now, I don't need to look at the raw audio data decoded
> > by the MP3 task as long as I can mix with it an other raw audio stream.
> > I fact I need to mix a MP3 stream and a G711|G729|ILBC|AMR stream. You
> > can see it as a kind of karaoke: mixing music (MP3) and voice (low
> > bandwidth codec). The result should simply be available on the output
> > jack.
> >
> > Did you think it is already doable now ?
>
> Yes, this is certainly doable already. I don't have any G7.11 data to
> hand, but have tried it by mixing ogg and mp3 data (ogg using Tuomas
> Kulve's gstreamer plugin which uses the pcm dsp sink).
>
> E.g. These two commands can be run is separate terminal windows and are mixed:
>
> gst-launch-0.10 filesrc location=20-16000HzExp5sec.mp3 ! dspmp3sink
>
> gst-launch-0.10 filesrc location=opensource.ogg  ! application/ogg !
> tremor ! dsppcmsink

gst-launch-0.10 filesrc location=20-16000HzExp5sec.mp3 ! dspmp3sink \
filesrc location=opensource.ogg  ! application/ogg !
tremor ! dsppcmsink

This way you can be sure that both pipelines are running on a single
process.  I'm not certain it is going to work as expected due to
constraints with two audio streams running at the same time, but you
can write as many source->filter->sink pipelines in a single
gst-launch as you want.

Thanks,

Daniel.

>
> So this uses the mp3 sink and the pcm sink simultaneously. I imagine
> it must be possible to start two separate sources in a single
> gstreamer pipeline and then send them to separate sinks (i.e. as I've
> done in the above example but all in one command). Anyone know how to
> do this?
>
>
> Simon
>
>
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