[LAD] python, gtk, gstreamer

drew Roberts zotz at 100jamz.com
Thu Feb 28 02:37:04 UTC 2013

On Wednesday 27 February 2013 18:51:34 Patrick Shirkey wrote:
> On Thu, February 28, 2013 8:14 am, drew Roberts wrote:
> > Ignorant here. Trying to scrounge around and make something work for a
> > demo
> > purpose.
> >
> > In python I am trying to build this pipeline:
> >
> >     pipeline_txt = (
> >             'jackaudiosrc ! '
> >             'level name=level interval=1000000000 !'
> >             'jackaudiosink')
> >
> >     pipeline = gst.parse_launch(pipeline_txt)
> >
> > I have been trying that a number of ways.
> >
> > So, I basically watch the bus for level info.
> >
> > In a subroutine, I can print the peak info to the terminal.
> >
> > I can't seem to figure out how to pass this info back to the rest of the
> > program so that I can hook it up to a graphical meter.
> Add a call to the callback for the meter to set the meter value from the
> subroutine?
> > Cna anyone point me to some simple code doing something like this? Give
> > me some clues that might help someone who seems to be being very dense
> > for days
> > now?
> Sounds like you just need to connect the meter to the subroutine but it's
> a bit had to say without a bit more code to demonstrate how you are
> setting up the meter.
> A few questions...
> Is the meter a class of it's own or just a widget in a draw routine?
> Do you have a "set_meter_value" type of function or are you just calling
> directly to the meter widget's value?
> What UI toolkit is the meter using?

Right now, I have not even tried to make a meter, I just want to get the peak 
value out of the subroutine and print it from outside. I can print it from 
the inside but can't even figure out how to get it out.

One  sample I started working with (there are others but this is one) can be 
found here:


In the def show_peak(bus, message):

there is:


but this is more of a "batch" type setup rather than an interactive one.

So let's say I do something like this instead:

	zpeak = message.structure['peak'][0]
	#print "message.structure: "
	print zpeak
	return zpeak

along with making a jack source and sink instead of a file source and fake 

I can get the peaks printed in there via the print zpeak.

But I am going around in circles (actually, circles is too clean a shape) in 
my head trying to figure out how to get that info out as it comes in.

Once I ge that, then I have to figure out how to hook it up to a meter widget.

One possibility I have looked at basing this on is this:


> --
> Patrick Shirkey
> Boost Hardware Ltd

all the best,


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