Re: Audigy2 in SNDRV_PCM_FMTBIT_S32_LE mode.

[Takashi Iwai <tiwai@suse.de>]

At Tue, 18 May 2004 17:03:17 +0100,
James Courtier-Dutton wrote:
> 
> Takashi Iwai wrote:
> > At Tue, 18 May 2004 16:47:01 +0100,
> > James Courtier-Dutton wrote:
> > 
> >>What would I need to change in the emu10k1 driver, to get alsa-lib to 
> >>send it 32bit audio samples.
> >>I tried just adding the SNDRV_PCM_FMTBIT_S32_LE to the playback options, 
> >>but that did not work.
> >>
> >>When I did that, everything just played at half speed.
> >>
> >>Can anyone give me any pointers as to where else I should change things 
> >>in order to get 32bit audio to the Audigy2 DSP.
> > 
> > 
> > AFAIK, emu10k1 engine processes only 16bit PCM.
> > or do you know the register (or anything else) to handle 32bit data
> > for audigy?
> > 
> > 
> > Takashi
> > 
> > 
> 
> The SB Live DSP can only handle 16bit PCM.
> The SB Audigy DSP can handle 24/32 bit PCM.
> 
> I am working from what someone has told me to get 24bit sound. Send it 
> to the Audigy inside a 32bit value: -
> For playback:
> You can use voice grouping - alloc 4 FX busses for 1 stereo stream
> or use TRAM.
> 
> Does this help you ?

if i understand the above correctly, audigy can assign 4 mono streams
as a stereo (interleaved?) 32bit stream.
it's similar as emu10k1 uses 2 mono streams for a single stereo 16-bit
interleaved stream.

in the case of 16-bit stereo, CPF_STEREO_MASK is used to toggle this
mode.  so, there must be a similar register switch for 32-bit mode.
otherwise it can't work...


Takashi


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