[Mplayer-cvslog] CVS: main/DOCS sound.html,1.68,1.69

[Anders Johansson]

Hi,

> > > while the MASTER is an analog control. This means that when lowering the PCM
> > > sound level the SNR is lowered. If one then compensates by increasing the
> > > MASTER level the result is a output signal with poor dynamic range combined
> > > with the noise created by the crappy amplifier on the sound card.
> > Then why some cards have distortion when PCM is maxed out?
> > BTW I'm not an audiophil at all, as you may have guessed :)
> 
> My guess is that on some soundcards, PCM is a digital control with
> some default value (75?) being no change, and greater values
> amplifying the samples digitally (=horrible distortion). However, I
> imagine all of this varies from card to card... I don't see any reason
> that PCM should be digital on all cards....
> 

I think you are right. It seems that some (older and cheaper) cards
have an analog mixer for the PCM data after the D/A followed by a
analog master mixer. More expensive and newer cards have a digital
premixer where even the sound from the mic and CD is digitized before
it is mixed. On these cards the master volume control is often an
analog mixer which is a part of the D/A converter. SB Audigy and the
Midiman cards works this way. Some ridiculously expensive cards like
the ones from RME doesn't have any analog volume control at all, on
these cards all mixing is done digitally by the chipset.

> Rich

//Anders