This is interesting. It appears the callback function is not called frequently enough. Really weird.. it must be some bug in my code.
You see, I have a sample rate of 44100hz per second, and a buffer size of 64. This basically means that for 1 second of audio I need to fill ~680buffers per second in my callback (the callback is called ~680 times per second, and each buffer is 64 frames in size), so ~680 * 64 = ~44100. The C code gets its callback called around 680 times, but interestingly the D code gets its callback called only 29 times. This is why I hear the sound stuttering, its because my callback isn't getting called frequently enough and the audio card is filling the missing buffers with zeros. Now I have to figure out why it's not getting called often enough. On 10/18/10, Andrej Mitrovic <[email protected]> wrote: > Yeah, that's what I would usually do. The trouble is there's a library > in DLL format, and there's only a couple of calls to it and that's it. > But somehow the C client code performs better. I've just tried a D1 > sample, with the same result. I'll have to investigate.. > > On 10/17/10, Denis Koroskin <[email protected]> wrote: >> On Mon, 18 Oct 2010 01:10:31 +0400, Andrej Mitrovic >> <[email protected]> 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. >> >
