[pulseaudio-discuss] 24 bit sound

Tanu Kaskinen tanuk at iki.fi
Fri May 7 06:47:00 PDT 2010

On Fri, 2010-05-07 at 10:01 +0200, David Björkevik wrote:
>   * If I buy a 96kHz / 24 bit card, use PulseAudio, and play such a
> .wav-file through mplayer, is that the rate and depth of audio that will
> be sent to the sound card?

Yes, assuming that the sink is configured to run at 96 kHz / 24 bit. By
default it won't be running in that mode - the default mode is 44.1
kHz / 16 bit. The easiest way to modify the sink mode is to put

    default-sample-format = <mode>
    default-sample-rate = 96000

in /etc/pulse/daemon.conf (I think this should be configurable in some
GUI, but currently that's not possible). <mode> is one of these: s24le,
s24be, s24-32le, s24-32be, s32le, s32be, float32le, float32be, depending
on the sound card. I guess some of those is the most common sample
format, but I don't know which (and I don't know off-hand how to find
out which one is used by your card, other than by trying each and seeing
which one works).

>  * With such a card, if I disable the alsa mixer and just use software
> mixing in PulseAudio, will the full 24 bit depth be utilized,
> effectively causing little or no degradation on sound quality when
> playing back a 16 bit sample?

Yes. (Btw, whatever you mean by "disable the alsa mixer", that's most
likely something you don't have to care about, if your Pulseaudio is set
up in the normal way.)

Tanu Kaskinen

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