[Stk] prototyping in python?

[Iain Duncan]

Hi Gary, Antoine, and any lurkers. I'm hoping to do the exact same audio
gen in an adaptation of the crtsine.cpp example in the stk and with
Antoine's py example so I can figure out just how much penalty doing it
python incurs. Unfortunately, I must be missing something, because in the
cpp example I get silence. If anyone can see my error, or knows why it
wouldn't work the same way, that would be helpful. Thanks!

Here is the audio gen code from the PyRtAudio examp:

def __call__(self):
   self.idx += 1
   # deleted the ascending scale code
   return 0.5 * cos( 2. * 3.1416 * self.freq * self.idx / SAMPLE_RATE )

And here is my attempt to do it in C++, not getting any sound:

int tick( void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames,
double streamTime, RtAudioStreamStatus status, void *dataPointer )
{
    // buffer to fill
    register StkFloat *samples = (StkFloat *) outputBuffer;
    int freq = 440;

   // loop through the number of samples we need to fill, filling the
output buffer
   // samp_index is a global int counter
   for ( unsigned int i=0; i<nBufferFrames; i++, samp_index++ ){
     *samples++ = ( 0.5 * cos( 2.0 * 3.1416 * freq) * samp_index /
SAMPLE_RATE );
   }

   return 0;
}



On Wed, Nov 2, 2011 at 1:02 PM, Iain Duncan <iainduncanlists at gmail.com>wrote:

> Preliminary tests seem to imply this works really well actually. I'm
> pleasantly surprised, I was able to put some pointless number crunching in
> the non-audio thread and spit to the screen, sending my python process up
> to 30-40% Cpu use and gnome -terminal up to about 50% ( on a quad core chip
> mind you ) without noticing any underruns. Mind you, I have no idea what
> the real latency is, I have my buffer set at 64, but dac.getStreamLatency()
> is reporting 0.00 so I might have to benchmark.
>
> Wondering if either of you would happen to have an idea of how I could
> easily make the audio gen really audio heavy?
>
> An ideal benchmark I think would be to get some audio-in, process it, and
> spit it out, but that may take a while.
>
> The gen as is now:
>
> 0.5 * cos( 2. * 3.1416 * self.freq * self.idx / SAMPLE_RATE )
>
> perhaps making a matrix of a whole bunch of those would do it.
>
> thanks
> Iain
>
>
>
> On Wed, Nov 2, 2011 at 12:52 PM, Iain Duncan <iainduncanlists at gmail.com>wrote:
>
>> Thanks Gary, I got in touch with Antoine and will be helping to extend
>> that example.
>>
>> thanks
>> iain
>>
>> On Wed, Nov 2, 2011 at 10:58 AM, Iain Duncan <iainduncanlists at gmail.com>wrote:
>>
>>> Well it works, and it seems to be running ok on my box ( some clicking,
>>> but the sine sounds clean ).
>>>
>>> I noticed the python file has a mixture of spaces and tabs, so it opened
>>> up looking funny in my editor, I'm converting that. I emailed Antoine to
>>> see if he's still working on this or what the status is. I'll definitely
>>> play around with it. I assume none of the other stk stuff has been ported
>>> given that Python is not really appropriate for real time dsp eh?
>>>
>>> Looking over my notes I realized I got busy and never tested the crtsine
>>> example on my firepod for you, I'll get to that to.
>>>
>>> thanks
>>> Iain
>>>
>>>  On Wed, Nov 2, 2011 at 7:24 AM, Gary Scavone <gary at ccrma.stanford.edu>wrote:
>>>
>>>> Hi Iain,
>>>>
>>>> If it helps, there is a python wrapper for RtAudio in the latest
>>>> release of RtAudio (look in the "contrib/python/" directory).
>>>>
>>>> --gary
>>>>
>>>> On 2011-11-02, at 12:22 AM, Iain Duncan wrote:
>>>>
>>>> > Hi, I'm working on an a project that I intend to do using the STK,
>>>> but am hoping I can prototype the architecture in python until I've figured
>>>> out the various components and their responsibilities and dependencies.
>>>> Does anyone know of any kind of python library ( or method? ) that would
>>>> let me simulate the way callback based STK apps using RTAudio work? IE I
>>>> want to have a python master callable that gets called once per audio
>>>> sample and has a way of sending out it's results.
>>>> >
>>>> > I've found a bunch of python audio libs but it doesn't seem like they
>>>> work that way, maybe I'm missing something?
>>>> >
>>>> > thanks!
>>>> > Iain
>>>> > _______________________________________________
>>>> > Stk mailing list
>>>> > Stk at ccrma.stanford.edu
>>>> > http://ccrma-mail.stanford.edu/mailman/listinfo/stk
>>>>
>>>>
>>>
>>
>
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