RE: [GD-Windows] Streaming WAVE audio

[Brian H. <bri...@py...>]

At 09:36 AM 4/28/2002 -0700, Jon Watte wrote:
>Yeah, that'd do it. If you count it, you're running with only a single
>buffer, if this is what you're doing.

Yeah, that was part of me being lazy and tired -- I didn't run through 
simulation steps.

> > Changing it to this fixed it:
> >
> > waveOutWrite( nextBuffer );
> > fillBuffer( completedBuffer );
> > waveOutWrite( completedBuffer ); //keep the chain going
>
>This can't possibly work right, as you enqueue two buffers for each
>buffer played. I think you actually mean something else, such as
>just calling fillBuffer() and waveOutWrite().

Actually, using your nomenclature, where "nextBuffer" indicates the 
"nextBuffer to be filled", I was doing this:

waveOutWrite( ( nextBuffer + 1 ) % 3 );
fillBuffer( nextBuffer );
waveOutWrite( nextBuffer );
nextBuffer = ( nextBuffer + 1 ) % 3;

And you're right, it didn't make sense -- it WORKED, but only because 
waveOutWrite is friendly when you send it a buffer it can't use.  In the 
case of the first completion, nextBuffer+1 would have pointed to a 
previously INQUEUED buffer, generating an error (which would be silent if 
the return values weren't checked...fwiw, the return value was '33', which 
isn't an MMSYSERR_xxxx).

So basically that first waveOutWrite() wasn't doing anything -- in fact, it 
was a legacy of my initial implementation where I always tried to have a 
premixed buffer waiting to go next.  That is, the completion routine was 
expecting to dispatch _immediately_ to avoid any hiccups, it originally 
didn't have any other buffers queued waiting to go.

That's the problem with long debugging sessions -- you start getting old 
code interfering with new code, but you're so tired and pissed you're 
scared to change stuff that seemingly works =)

>setup:
>   memset( buffers[0], QUIET, SIZE );
>   memset( buffers[1], QUIET, SIZE );
>   memset( buffers[2], QUIET, SIZE );
>   prepareBuffer( 0 );
>   prepareBuffer( 1 );
>   prepareBuffer( 2 );
>   nextBuffer = 0;

That's exactly what I was doing.

>start:
>   queueBuffer( 0 );
>   queueBuffer( 1 );
>   queueBuffer( 2 );

Ayup.

>completion:
>   fillBuffer( nextBuffer );
>   queueBuffer( nextBuffer );
>   nextBuffer = (nextBuffer + 1) % 3;

Yup.

The above is pretty much identical to the code I have now, but with my last 
e-mail I had a spurious queueBuffer((nextBuffer+1)%3) before I did the fill 
buffer.

Brian