Just a quick question...

Just a quick question...

[Jim]

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I beleive that many modern cards have multiple hardware channels (err not channels' that's like stereo... uhmm streams?) ?  I've been browsing through the documentation, examples, faq's etc, and have found no refernence to such things... So was wondering, does ALSA support multiple opens to get multiple hardware (...) to allow the hardware itself to mix?  Is this even a thing?  and if not - then what's it mean when a sound card has 256 channels?  (64 3D) ...

And if it IS supported - any chance that on the driver page a field could be added that's 'simultaneous opens?'

Jim

Maybe I'm asking something that's meaning something other than what I do mean :) 

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Re: Just a quick question...

[Patrick Shirkey]

Jim wrote:
> I beleive that many modern cards have multiple hardware channels (err 
> not channels' that's like stereo... uhmm streams?) ?

You are correct.

>  I've been browsing 
> through the documentation, examples, faq's etc, and have found no 
> refernence to such things... So was wondering, does ALSA support 
> multiple opens to get multiple hardware (...) to allow the hardware 
> itself to mix?  Is this even a thing?  and if not - then what's it mean 
> when a sound card has 256 channels?  (64 3D) ...
>  

It's called hardware mixing and there is not much info availabel about 
it. There are a few cards/devices with ALSA drivers theat have support 
for hardware mixing. There are a few that have the capability but no 
support because the manufacturers  refuse to probvide the necessary 
specifications.

> And if it IS supported - any chance that on the driver page a field 
> could be added that's 'simultaneous opens?'
>  

Maybe not a field but a note. Lets call it [G] :)

> Jim
>  
> Maybe I'm asking something that's meaning something other than what I do 
> mean :)



-- 
Patrick Shirkey - Boost Hardware Ltd.
For the discerning hardware connoisseur
Http://www.boosthardware.com
Http://www.boosthardware.com/LAU/guide/
========================================



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Re: Just a quick question...

[Jim]

>
> Unfortunately the i810 driver is one of the undisclosed code family. I
> haven't used the nforce so I don't know about it.

I went out looking for information - being from Intel - SURELY it's
documented, and such information is publicly available.... I've found a
plethora of information - but everything about the design of the ac97 spec
indicates one register set, one set of dmas ... one could interpret one
portion... there's 256 ranges of base registers one can select - but then
you'd have a full set of mixing registers etc - just totally impracticle :/
and therefore 256*3 dma units ... which isn't all that much memory bandwidth
at 256*44.1khz*16*2 is only 45MB/sec ...  less than a hard disk... and I
don't understand the PCI interface entirely.... but then I did go back to
nVidia's page on the nForce chip






informative links regarding the ac '97 chip aka i810 audio controller...

http://www.intel.com/design/chipsets/manuals/298028.htm

slightly different information...
http://www.intel.com/design/chipsets/manuals/298238.htm

directory containing ac97 specs...
ftp://download.intel.com/labs/media/audio/download/

page detailing statuses etc (links for download are broken see prior link)
http://www.intel.com/labs/media/audio/index.htm
>


> The ones that I know work are the trident, the es1968 (maestro), the
> interwave. I think there are a few more but cannot remember. It is a
> question for the LAU FAQ though so I'll try to find out some more.
>
> --
> Patrick Shirkey - Boost Hardware Ltd.
> For the discerning hardware connoisseur
> Http://www.boosthardware.com
> Http://www.boosthardware.com/LAU/guide/
> ========================================
>



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