Re: Asus Xonar DX (AV200) dmix resampling

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Wiebe, Clemens, list:


On Thu, May 16, 2013 at 4:23 AM, Wiebe Cazemier <wiebe@xxxxxxxxxxxx> wrote:
----- Original Message -----
> From: "Clemens Ladisch" <cladisch@xxxxxxxxxxxxxx>
> To: "Wiebe Cazemier" <wiebe@xxxxxxxxxxxx>
> Cc: alsa-user@xxxxxxxxxxxxxxxxxxxxx
> Sent: Thursday, 16 May, 2013 9:38:10 AM
> Subject: Re: Asus Xonar DX (AV200) dmix resampling
>
> > Now that high-end cards don't do this anymore, it seems to defeat
> > the
> > purpose to then put it in software.
>
> Modern cards don't do this anymore because *all* operating systems
> already do software mixing.

But don't they do this because cards don't hardware mix anymore?

Hmm chicken and egg how fun!

Another thing to think about is gapless playback.  How well does this work when a 44.1/16 song is followed by a 96/24 song?  The usual functionality is to mix the tail of one with the front of the other; I guess that means downsampling the latter (or a serious application of magic).
 

>
> > I understand it's necessary for mixing sources, but doesn't one
> > like
> > to retain full quality when there is one source?
>
> This is a restriction of dmix; using one predetermined sample rate
> avoids communicating between multiple instances.  Modern desktops use
> PulseAudio instead.

"Can't.... use ... new ... technology..." :)

I guess I have to give Pulse a try. Choosing the sample rate of the first stream is what would suit me. I don't care what music sounds like while I'm skyping, but when I'm just listening to music, I want original quality.

Wiebe please bear in mind that this is just my (perhaps valueless) opinion, but Pulse will cause you pain and agony.

The /etc/pulse/daemon.conf seems to like the idea of a fixed sample rate (looking at my computer, 44.1khz) and to want to resample to that.  I have in the past stumbled upon conversations about configuring pulse so it's bit-perfect but for me the Thing That Works is to use a player like guayadeque or quod libet or something + mpd that will talk directly to Alsa.
 

>
> Anyway, in what way does resampling from 192 to 48 kHz reduce
> quality?
> Are you a bat?  ;-)

While I agree that I find the whole HD audio stuff a bunch of marketing hype (CD quality is good enough for human hearing), I think it too bold of the subsystem to just downmix to 48 kHz, mostly because any resampling theoretically introduces aliasing artifacts. 

Being somewhat nervous of accusations of trying to start a discussion worthy only of an audio equipment enthusiast group (at best)....

I am not a bat either (in fact my ears aren't very young) but if I have the choice between some super-processed CD pressing perhaps from a 5th generation analogue copy vs. someone's effort to extract an analogue master at 96/24, or something that was originally recorded at higher resolution, I prefer to avoid the (possible) compression and gain limiting conversion to 16 bits and/or downsample, as well as the (possibly suspect) downsampling on my laptop.

It also seems apparent that DACs that take a little extra care in the analogue section tend to support 96/24 or higher anyway.

For what it's worth!
--
Chris Hermansen · clhermansen "at" gmail "dot" com

C'est ma façon de parler.
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