[mythtv-users] Audigy Sound Card Upgrade Worthwhile?

[alhaz at xmission.com]

Quoting Calin Brabandt <cbrabandt at yahoo.com>:

> "Steven Adeff" <adeffs.mythtv at gmail.com> wrote:
>
>> The nForce2 chipset has a superior audio system to
>> the Audigy (as do the ALC chips) because they don't
>> convert  digital to analog for processing and then
>> *back* to digital for S/PDIF like ALL the Creative
>> sound cards do. This doesn't affect AC3 or DTS, but
> it > does affect allnon AC3/DTS audio.
>
> I've never run Audigy soundcards under Linux but I
> have not found this to be the case with the KX drivers
> under Windows.  If this is the case with Linux, which
> I doubt, it's a driver problem or, more likely, a
> setup problem.  I think even the Creative Labs Audigy
> drivers are capable of bit-perfect SPDIF capture, if
> the mixer sliders are set to maximum and other
> SPDIF/Dolby settings are correctly configured.


I don't think capture was what he was talking about.

And, I don't know that the creative cards literally process outbound  
digital audio as analog - that doesn't make much sense to me.

What the vast majority of audio codecs do is convert everything to  
48khz. This isn't an issue if you're only watching DVDs, which are  
48khz anyway (excepting fairly rare 96khz dolby surround tracks), but  
if you plan on listening to music or using the audio capture  
capability of a brooktree/conexant tv tuner, it's a problem, because  
there is no good or cheap way to convert 32khz or 44.1khz to 48khz  
without huge amounts of aliasing. To avoid aliasing when converting  
44.1khz to 48khz, nyquist demands that you upsample to about 580khz  
and then downsample to 48khz, else you get distortion at iirc 6khz  
intervals throughout the spectrum.

Some of the ALC chips allow multiple sample rates out, most don't. I  
know for sure that SB Live and Audigy 1 boards don't. Dunno about  
later Audigy products.