Anyone using Portaudio?

[Denis Koroskin]

On Mon, 18 Oct 2010 01:10:31 +0400, Andrej Mitrovic  
<andrej.mitrovich at none.com> wrote:

> There's a .d header file in the Bindings project on dsource which I'm  
> using with the Portaudio DLL v19, and I'm implicitly loading the DLL.  
> There's a  sine playback example, and I'm comparing the usage of  
> Portaudio from the C sine example (patest_sine.c) compared to the D one  
> (patest_sine_hello.d). The C and D code are almost identical, however  
> there seems to be a pretty big overhead when using D.
>
> I can safely use a buffer size of 64 frames in the C example, but in the  
> D one the minimum I could get was around 1800 frames.
>
> I've tried compiling with-O -release -inline, and issuing a call to  
> GC.disable() before the call to Pa_StartStream(). I've also tried  
> compiling the portaudio DLL in Release mode. But none of this had any  
> effect. Anything lower than 1800 for the buffer size gives me choppy  
> sound in D.
>
> There shouldn't be a problem with such a small buffer size, all the data  
> is preallocated and the buffers are prefilled with data, so it can't be  
> a CPU bottleneck issue. Since D uses C functions directly, I just don't  
> see where the overhead could be.
>
> Has anyone used Portaudio with D2 (or D1 for that matter) with  
> close-to-equal performance as when using C?

 From my experience, starting with D that purely calls C code and then  
slowly porting it to D (one piece of code at a time) usually helps  
revealing the problem. Just try to keep it the same (i.e.  
interchangeable). You can do that by marking functions as extern (C) and  
optionally having some of the variables as extern (C) __gshared.