Re: [LAD] Do professionals use Pulse Audio? ; xfce4-mixer

On Wed, 25 Apr 2018, Philip Rhoades wrote:

> I am not a professional LA user but I have regard for what serious LA
> users have to say. A post turned up on the Fedora XFCE list about
> removing xfce4-mixer for F29 - I responded with:
>
> "Every time I upgrade I immediately UNinstall PA and use ALSA only - so
> I still depend on xfce4-mixer . ."
>
> Someone replied that PA has greatly improved since the early days
> especially and "controlling streams separately is an added feature" -
> but I can do that with the .asoundrc I have now - are there any good
> reasons for me to reconsider the situation the next time I do a fresh
> install? (I realise I am likely to get biased comments here but I am
> not going to post on a PA list . .).

Having some kind of ALSA mixer is still required. Pulse controls levels as
a mix of sound card and digital gain stage levels. You have no way of
knowing what it is really doing. This is great for desktop use, absolutely
useless for any kind of profesional use. Note that input levels are worse
as pulse uses a mix of input level, input/mic boost (even on aux inputs)
and digital gain stage.

An interesting experiment is to run alsamixer and watch the audio card
control levels while adjusting pulse's one level control full range.
Input levels on the internal audio card will see the input level go up
then bounce to 0 as the boost is set up a notch then the level goes up
again, then down plus more boost. I have found that each boost level has
it's own unique noise that I can work around with alsamixer that pulse
tramples all over.

Pulse offers no guaranty of any particular audio card being used for sync
or of any source not having SRC applied.

Pulse offers no guaranty of no drop outs or stable latency.

Pulse offers no guaranty that some other application (skype is
particularely bad) will not change your audio card levels for you.

pulse makes a good audio front end for desktop applications so long as
Jackd is it's _only_ output. The Pulse-jackd bridge appears to be set up
as a client (using jack terms) rather than a device or back end. This
means that even when another device connected to pulse is not being used
for output, pulse continues to rely on it for sync :P This means that
jack free wheel will not work correctly if pulse has a connection to any
audio HW.

I personally use jackdbus as my audio server, started at session start. I
use pulse as a desktop front end with the pulse-jack bridge, but with the
udev and alsa modules removed so that jackd is it's only audio in/output.
This means pulse does not ever control audio device levels, and free wheel
works correctly.

Jack (or alsa direct) is the only way to do profesional audio is you want
bit perfect throughput. Pulse offers no such thing. I agree pulseaudio has
improved a whole lot, but it is no replacement for jack or alsa direct.
Alsa direct is great except if you want to be able to mix two audio
sources without stopping your proaudio application.

I have no comments on xfce4-mixer. I don't use it because I have an
ice1712 based card that has it's own much better control utility
(mudita24) and I find qasmixer (and it's extra tools) easier to use. I
also still use alsamix in a terminal because it is faster to access in
many cases :)

So I am not of the "pulse must be removed" community, but I still feel
that pulse is a long way from usable in any kind of profesional audio (or
even semiprofesional) environment. I would even go so far as to say it
never will be because it's original design goal was as an easy to use
desktop application/server. The possibility to do pro-audio would require
starting over not patching.

--
Len Ovens
www.ovenwerks.net
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