28 Feb
2013
28 Feb
'13
1:25 p.m.
Date: Wed, 27 Feb 2013 14:05:40 +0100
From: "Kaj Ailomaa" <zequence(a)mousike.me>
To: linux-audio-user(a)lists.linuxaudio.org
Subject: Re: [LAU] Jack users - how many channels do you want with PA
module-jackdbus-detect?
I don't typically think of "stereo", but, just 2 channels that happen
to be left and right.
I don't pretend to know about PA. I'm guessing, from your question,
that PA has the concept of pairing two JACK sinks/sources as a stereo
sink/source?
I happen to agree. If there are x PA devices on my MOBO, I want to see
x of them in JACK.
Not sure if we're talking about the same thing here. I wasn't suggesting
we make devices not show. Only that the module connecting PA to jack would
be stereo by default.
28 Feb
28 Feb
11:30 p.m.
New subject: Jack users - how many channels do you want with PA module-jackdbus-detect?
On Thu, February 28, 2013 4:25 am, Mac wrote:
Pulse audio thinks in stereo, not channels.
Date: Wed, 27
Feb 2013 14:05:40 +0100
From: "Kaj Ailomaa" <zequence(a)mousike.me>
To: linux-audio-user(a)lists.linuxaudio.org
Subject: Re: [LAU] Jack users - how many channels do you want with PA
module-jackdbus-detect?
I don't typically think of "stereo", but, just 2 channels that happen
to be left and right.
I happen to agree. If there are x PA devices on my MOBO, I want to see
x of them in JACK.
Not sure if we're talking about the same thing here. I wasn't suggesting
we make devices not show. Only that the module connecting PA to jack
would
be stereo by default.
I don't pretend to know about PA. I'm guessing, from your question,
that PA has the concept of pairing two JACK sinks/sources as a stereo
sink/source?
Pulseaudio is designed to work with the standard desktop audio setup:
-left and right input or mic input (mic is normally mono on L/R)
- 2 to 8 outputs labeled:
1)stereo
2)4.1
3)5.1
4)7.1
5)spdif out, normally stereo (ASE3/spdif are stereo standards)
but may be encoded as surround.
A stereo signal that is converted to a 4.1, 5.1, 7.1, may have a left and
right channel that is different than the original stereo signal. So unless
you are using a pulse/jack bridge to do surround sound output, you need a
stereo line from pulse to jack to get the same two channels that went in.
Personally I have not noticed the difference, but then an MP3 is not
quality audio, it already sounds "off" (the kind of off milk left out
goes).
Jackd, is a multi-channel setup. Any one channel is on it's own and not
connected to any other except for being in sample sync.
So any audio coming from Pulse has to be expected to having been dealt
with as stereo, that is, if there is some effect on one side, it will be
on the other as well. (or if there are more than two channels they will
have been all effected together as well) Any audio going to Pulse, must be
expected to be effected together on their way to whatever app is capturing
that audio via pulse.
The PA-jack bridge is not only a bridge between audio servers, but a
bridge between two different paradigms. A channel paradigm on the jack
side and a stereo/surround paradigm on the pulse side. A bridge between
the desktop and pro-audio. In this case, the best way for pulse to see
jack is as a stereo sound card with no controls. The only time more
channels should be granted to Pulse is if the desktop is using jack as a
surround device for playback to a firewire device. Any other device does
not need jack at all and can playback surround directly to the audio
device on it's own.
If we are creating a surround recording in jack, we don't need pulse at
all and can do all our surround processing in jack.
No matter what pulse defaults to in channel numbers, it will always allow
configuring to as many channels as the device supports if the default is
not what the user wants.
--
Len Ovens
www.OvenWerks.net
11:48 p.m.
New subject: Jack users - how many channels do you want with PA module-jackdbus-detect?
On Thu, Feb 28, 2013 at 02:30:32PM -0800, Len Ovens wrote:
No matter what pulse defaults to in channel numbers,
it will always allow
configuring to as many channels as the device supports if the default is
not what the user wants.
I hope it can be configured as well to just create its Jack ports and
NOT connect them to whatever device Jack is using, leaving this to
the user.
This is required if any processing is done before the signal goes
to the hardware (room correction or EQ, crossover filters, etc.).
It is also required if PA is providing e.g. a telephone signal
which probably should connect to a SW mixer and not directly to
the HW output.
Ciao,
--
FA
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
11:52 p.m.
New subject: Jack users - how many channels do you want with PA module-jackdbus-detect?
On Thu, 28 Feb 2013 23:48:03 +0100, Fons Adriaensen <fons(a)linuxaudio.org>
wrote:
On Thu, Feb 28, 2013 at 02:30:32PM -0800, Len Ovens
wrote:
It autoconnects, which I think is totally fine for most use cases.
In some cases one would of course like to configure that, just like with
any application. There's no parameter for autoconnection yet, to my
knowledge. Something one would like to be able to set for any jack
applications in fact.
No matter what pulse defaults to in channel
numbers, it will always
allow
configuring to as many channels as the device supports if the default is
not what the user wants.
I hope it can be configured as well to just create its Jack ports and
NOT connect them to whatever device Jack is using, leaving this to
the user.
This is required if any processing is done before the signal goes
to the hardware (room correction or EQ, crossover filters, etc.).
It is also required if PA is providing e.g. a telephone signal
which probably should connect to a SW mixer and not directly to
the HW output.
Ciao,
1 Mar
1 Mar
12:29 a.m.
New subject: Jack users - how many channels do you want with PA module-jackdbus-detect?
On Thu, February 28, 2013 2:48 pm, Fons Adriaensen wrote:
On Thu, Feb 28, 2013 at 02:30:32PM -0800, Len Ovens
wrote:
Yes that has been available for some time.
in /etc/pulse/default.pa there is a line like:
load-module module-jackdbus-detect
Change it to:
load-module module-jackdbus-detect connect=no
And pulse will not auto connect. I have had this set on my system and a
jack session set up to just connect what I want.
The number of channels Pulse bridges has quite a large effect on cpu use.
No matter what pulse defaults to in channel
numbers, it will always
allow
configuring to as many channels as the device supports if the default is
not what the user wants.
I hope it can be configured as well to just create its Jack ports and
NOT connect them to whatever device Jack is using, leaving this to
the user. This is required if any processing is done before the
signal goes
to the hardware (room correction or EQ, crossover filters, etc.).
It is also required if PA is providing e.g. a telephone signal
which probably should connect to a SW mixer and not directly to
the HW output.
I agree.
The pa-jack bridge is still in development, though I think it is not that
near the top of the list of priorities :) The channels=x parameter is in
git I am told, but not in the release packages I am aware of.
There is also some talk about moving the package system defaults to
/usr/share so that a distro can drop it's own config file into /etc/pulse
without over writing the package defaults. There is also ~/.config/pulse/
where a user could add this. Though to be honest I am not sure how.
--
Len Ovens
www.OvenWerks.net
4222
days inactive
4222
days old
linux-audio-user@lists.linuxaudio.org
4 comments
4 participants
participants (4)
-
Fons Adriaensen -
Kaj Ailomaa -
Len Ovens -
Mac