Re: [Rhythmbox-devel] Python Plugin-LED Cube Visualizations

[Jonathan Matthew <jonathan d14n org>]

On Fri, May 01, 2009 at 04:33:14PM -0700, EmbeddedMicro wrote:
> 
> Another question, how do I isolate the magnitude part. I though it would have
> been something like message.magnitude but that does not work.
> 
> Also I am getting messages on play/pause. How can I get only the messages
> that contain the magnitude info.

These are GStreamer questions, so I'd suggest first reading the GStreamer
application developers manual and API documentation (the python API is similar
to the C API), looking for example code, then asking on the GStreamer IRC
channel or mailing list if you have further questions.

I've never used the GStreamer spectrum element before, so I can't give
definitive or even particularly well informed answers, but I'll have a go..

- the magnitude would be a part of the message structure, so
msg.structure['magnitude'] would probably give you something (the element documentation
should be useful here)

- if you only want the spectrum information messages, connect to the
'message::element' signal and check that the message source is the spectrum
element (msg.src == self.spectrum)

- the messages are emitted as the spectrum element processes data, not as the
data is actually played.  There is a way to synchronize with the pipeline using
the timestamp data in the messages, but I don't know the details.