[gst-devel] LADSPA stereo plugins

[Stefan Kost]

On 20.06.2010 00:18, Remi+ wrote:
> Hi,
>
> I'm a beginer in Gstreamer, so perhaps my question is stupid.
>
> I'd like to record sound on ALSA (or Pulse) input and modify this sound
> with LADSPA plugins.
> It's Ok for me for LADSPA Mono plugins not for Stereo ones.
> (examples with swh-plugins)
>
> Using Mono sc4 LADSPA plugin OK :
> ---------------------------------
> gst-launch-0.10 --gst-debug-level=1 \
> autoaudiosrc ! progressreport name=Source update-freq=1 ! \
> audioconvert ! \
> audio/x-raw-float,channels=1,width=32,rate=44100,endianness=1234 ! \
> ladspa-sc4m ! audioconvert ! flacenc ! filesink location=f.flac
>
> Using Stereo sc4 LADSPA plugin KO.
> ----------------------------------
> gst-launch-0.10 --gst-debug-level=1 \
> autoaudiosrc !
> audio/x-raw-int,channels=2,width=16,depth=16,signed=true,rate=44100,endianness=1234
> ! \
> progressreport name=Source update-freq=1 ! \
> audioconvert ! \
> audio/x-raw-float,channels=2,width=32,rate=44100,endianness=1234 ! \
> deinterleave name=di \
> di.src0 ! queue ! audioconvert ! \
> audio/x-raw-float,channels=1,width=32,rate=44100,endianness=1234 !
> limit.Left_input \
> di.src1 ! queue ! audioconvert ! \
> audio/x-raw-float,channels=1,width=32,rate=44100,endianness=1234 !
> limit.Right_input \
> ladspa-sc4 name=limit \
> limit.Left_output ! audioconvert ! il.sink0 \
> limit.Right_output ! audioconvert ! il.sink1 \
> interleave name=il ! audioconvert ! flacenc ! filesink location=f.flac
>
> In gst-inspect, I can see that Stéréo plugins have 2 sound sink input
> and two src output. So I thinbk I should deinterleave left and right
> channel. My problem is gtreamer start but don't process signal input.
> Output file is empty and progress is stuck at 0 seconds.
>
> I really don't konw how to do...
>
> So my main question is :
> How to use LADSPA stereo plugin in Gstreamer ?
>   
this is all due to some over simplicity in ladspa (and still in lv2,
outch) - channel pairs cannot be detected (lv2 has a proposed
extension). In your example above you should not need the audioconverts
before ladspa-sc4 element. Now sure if you would need yet another queue
after interleave. If that does not help it could be another bug in the
ladspa wrapper.
maybe you could try more variants of the above pipeline to narrow it
down (e.g. leave out the ladspa-sc4 and just connect the
deinterleave/interleave ports). And finally file a bug with your findings.

Stefan

> Best regards,
> Rémi+
>
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