[Stk] RTAUDIO Float64 vs 32 vs Integer SoundCard

[Perry Cook]

Hey Gary,

I’m feeling that this is likely not at the root of your audio crunchiness.
And I’m pretty certain that hard-wiring INT into format would not work.
STK assumes floats in the rough range +/- 1.0 throughout, and only
the last layer of the audio interface worries about getting it out to the
sound card.  I didn’t check all the RTAudio code but I think that format
type might be more wide-reaching than just the last audio hardware 
layer.

Spits and Fizzles on EFX sounds more like buffer/IO problems to me,
unless it’s purely signal (level) dependent, and in that case it sounds
more like clipping.  Starting with EFX, which has I/O and signal
processing, has too many potential areas for problems to happen
to be sure where things might be going wrong.  Maybe try a simpler 
demo yet (in the examples folder), like the single sine oscillator, or
playsimp on a really simple (sine wave ideally) .wav file.  Play with 
the gain a bit (from within the code) and see if clipping or other 
interruption occurs.  If you can get it to make a pure sine wave in 
real time that sounds like a pure sine wave (or play any sound file 
without distortion/clipping), then the FORMAT/32/64 is likely not the 
problem.  

Others please chime in if you have experience in this area.

PRC

> On Aug 27, 2016, at 5:51 PM, Gary Worsham <gary.worsham at gmail.com> wrote:
> 
> I understand I'm still messing around at the RtAudio stage, but I promise to ask some stk questions just as soon as I get this other stuff out of the way.
> 
> I accomplished 2 different things.
> 
> #1 I figured out how to determine the index of the USB interface and use this instead of "default" when picking the audio interface to use.
> 
> #2 I figured out how to get the USB interface down to the default position.  At least, let's say I changed some things and it's there but I couldn't actually explain it.  So now this interface is used by default with the stk example programs.  Yay!
> 
> Next issue is that for example, I am running "effects" via StkEffects.  The sound is very crunchy - not overdriven, but spits and fizzles with any signal at all.  I noticed in the effects.cpp:
> 
> effects.cpp:  RtAudioFormat format = ( sizeof(StkFloat) == 8 ) ? RTAUDIO_FLOAT64 : RTAUDIO_FLOAT32;
> 
> So we are choosing float 64 or float 32 format based on a runtime decision... however this particular interface only supports 32 bit int.  Seems like this code assumes support for 32 or 64 bit float.
> 
> Should I just hard-wire RTAUDIO_SINT32 in here to get started, or do I have to change the code itself to accommodate this?
> 
> Thanks,
> 
> Gary W.
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