26 Feb
2015
26 Feb
'15
5:18 p.m.
Hei.
I am running linux on a Debian machine with kx repositories, connected
to a Mackie Onyx 1640-i.
Linux kx 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt4-3 (2015-02-03) x86_64
GNU/Linux
04:00.0 FireWire (IEEE 1394): Texas Instruments TSB43AB23
IEEE-1394a-2000 Controller (PHY/Link)
When i record multitrack audio using Ardour and jackd, i see that the
sample frequency is set to 44100.
The audio files are also at 44100, according to file:
root@kx:/home/humla/akt3bolger/interchange/akt3bolger/audiofiles# file
bass-2.wav
<head> bass-2.wav: RIFF (little-endian) data, WAVE audio, mono 44100 Hz
After doing a mix of the material on a separate machine using Ardour3 at
44100, and dumping the mix internally to a 44100 WAV, i received a mail
from the band in which they tell me that the mix is faster and at a
higher pitch than the audio they recorded through a video camera at the
concert.
When i playback audio from the linux machine (like mp3s ) through the
firewire and the Onyx console, i get random switches of speed and pitch.
I have been working in professional audio, and i know there must be a
problem with the sample frequency lock and synch between the two
devices, so that one is on the wrong sample frequency, and "translates"
the bitstream wrongly. Normally in a digital audio chain you have a
machine that is "master" and one that is "slave".
The problem here is that the console has no display showing the sample
frequency it is locked at, and the Linux machine does not show any
master / slave feature in jack or ardour.
There is something strange going on here.
The machine has also another analog audio card:
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio
Controller (rev 02)
And i don't know how this could influence the setup.
26 Feb
26 Feb
8:26 p.m.
On 2015-02-26 16:18, sub wrote:
[...]
The machine has also another analog audio card:
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio
Controller (rev 02)
And i don't know how this could influence the setup.
Anyway, if you dont need/use this soundcard (which is the one integrated
in the mainboard, I suppose), then it should be better to blacklist it.
It means avoid loading the related kernel module.
To see which are the loaded modules do:
$ lsmod
To blacklist the unwanted module (say it is named: 'snd_hda_intel'), add
the line:
blacklist snd_hda_intel
to the '/etc/modprobe.d/alsa-base-blacklist.conf' config file.
Another way is:
- create a file '/etc/modprobe.d/snd_hda_intel.conf' containing
'blacklist snd_hda_intel'
('snd_hda_intel' is just an example... you should use the "right" module
name)
Run 'depmod -ae' as root (sudo)
Recreate your initrd with 'update-initramfs -u'
(See: https://wiki.debian.org/KernelModuleBlacklisting)
Here some info about fixing the audio setup:
http://wiki.linuxaudio.org/wiki/system_configuration
http://wiki.linuxaudio.org/wiki/system_configuration#using_firewire
Regards
--
al3xu5 / dotcommon
Support free software! Join FSF: http://www.fsf.org/jf?referrer=7535
11:15 p.m.
On Thu, 26 Feb 2015, alexus / dotcommon wrote:
If the internal Audio is not to be used most BIOS will let you disable it.
I always do this on my systems because HDA audio and "low latency" don't
seem to mix. The only way I can think of that one audio device will affect
the other when only one is tied to jack is if PA-jack bridging is being
used, but I have not seen fluctuation in sample rate this way from that.
(it is why I disable internal audio though)
The only similar thing I have had is if I have sync set to follow S/PDIF
when it is not there to follow and then the sample rate wanders. But there
does not seem to be any external sync options in your case.
Are you using the jack FW backend? or the new FW ALSA device?
--
Len Ovens
www.ovenwerks.net
The machine
has also another analog audio card:
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio
Controller (rev 02)
And i don't know how this could influence the setup.
Anyway, if you dont need/use this soundcard (which is the one integrated in
the mainboard, I suppose), then it should be better to blacklist it.
It means avoid loading the related kernel module. 
27 Feb
27 Feb
11:16 a.m.
Hi,
On 02/26/2015 11:18 AM, sub wrote:
When i playback audio from the linux machine (like
mp3s ) through the
firewire and the Onyx console, i get random switches of speed and pitch.
If
pulseaudio is involved, check these settings in /etc/daemon.conf
default-sample-rate
alternate-sample-rate
The default settings, I believe were 44100 and 48000 respectively and
this caused certain applications (skype, in particular) to have their
signals downsampled from 48k -> 44k. Was an interesting affect during
skype conversations but ultimately got annoying so I changed both
settings above to the same value (48000) and all is well.
2:56 p.m.
On Fri, 27 Feb 2015, David Santamauro wrote:
If pulseaudio is involved, check these settings in
/etc/daemon.conf
default-sample-rate
alternate-sample-rate
The default settings, I believe were 44100 and 48000 respectively and this
caused certain applications (skype, in particular) to have their signals
downsampled from 48k -> 44k. Was an interesting affect during skype
conversations but ultimately got annoying so I changed both settings above to
the same value (48000) and all is well.
Both of mine are set to 48k as well... Pulse complains at startup that
alternate is the same as default :) It doesn't really matter in my setup
as pulse never has direct control of any audio interface, jack sets the
sample rate, I have not noticed skype oddness.
For the OP, do you run the CPU in performance mode? Or is it ondemand? I
would not think the CPU frequency would have anything to do with the
sample frequency unless something was broken.... but running in
performance mode is more stable anyway.
--
Len Ovens
www.ovenwerks.net
3366
days inactive
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4 comments
4 participants
participants (4)
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alexus / dotcommon -
David Santamauro -
Len Ovens -
sub