Re: [Alsa-user] C-Media 8768+ Support

[Peter Z. <pz...@po...>]

I don't think this chip has hardware mixing and DD encoder in hardware. 
I think these features are in windows software drivers.

Peter Zubaj

Wilfried Weissmann wrote:

> Hi,
>
> I am interested in Alsa support of the C-Media 8768+ chipset, which 
> has a very promising feature list. However, all information that I 
> have found about this chip is somewhat vague.
> Currently I am using an Aureal Vortex 2 (8830) that supports hardware 
> pcm mixing. This card is connected to a Dolby Digital Decoder via 
> S/PDIF. This setup works great but only provides stereo PCM output 
> because the aureal has no Dolby Digital encoder. According to the spec 
> of the CMI8768+ it does support Dolby Digital Live encoding and 
> therefor enables me to use my 5.1 speaker setup.
> Does anyone know if the PCM mixing and Dolby Digital Live encoding of 
> the CMI8768+ is done in _hardware_ or is it done in software by the 
> (windows) driver?
> I had a quick look at the register spec and programming guide of the 
> standard CMI8768 and I could not find anything about Dolby encoding 
> for S/PDIF. Also the hardware mixing seems to be missing in 
> snd-cmipci.o which should be possible if the DirectSound 3D is indeed 
> supported in hardware. But there is nothing written about that in the 
> programmig guide.
> Does someone have access to the programming guide of the CMI8768+ so 
> that DDL and hardware mixing can be implemented? Does the chip even 
> support this?
>
> Greetings,
> Wilfried