On 9 Dec 2009, at 05:46, Philippe (Merov) Bossut wrote:
> Hi Aimee,
>
> I haven't looked in the code, just assumed you copied the relevant parts :)
>
> It seems to me that the intent of the code is to write in "newbuffer" by
> packets of "sizeof(MIXBUFFERFORMAT_T) == stride" bytes using "cursamplep" as
> a sliding pointer. That said then, having "stride == 4" when
> "MIXBUFFERFORMAT_T" is defined as S16 seems wrong.
>
> So the question is: why is "stride" set independently of
> "sizeof(MIXBUFFERFORMAT_T)"? Are there any situation where those 2 things
> need to be different? Looking at how "stride" is set should give you a hint.
MIXBUFFERFORMAT and stride are only set with:
#if LL_DARWIN
typedef S32 MIXBUFFERFORMAT;
#else
typedef S16 MIXBUFFERFORMAT;
#endif
and ...
#if LL_DARWIN
stride = sizeof(LLAudioEngine_FMOD::MIXBUFFERFORMAT);
#else
int mixertype = FSOUND_GetMixer();
if (mixertype == FSOUND_MIXER_BLENDMODE ||
mixertype == FSOUND_MIXER_QUALITY_FPU)
{
stride = 4;
}
else
{
stride = 2;
}
#endif
So stride seems only to be used as a (broken) hack when MIXBUFFERFORMAT is S16
and one of those two 32-bit mixer formats is in use, one of which wants S32,
the other which wants F32.
If on my Mac I set MIXBUFFERFORMAT to S16 and stride to 4, which should be the
same result as a PC using FSOUND_MIXER_BLENDMODE, the result is a really
horrible noise, as I would expect.
Aimee.
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