[maemo-developers] Using available DSP tasks

[From: Simon Pickering]

> 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

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