[ALSA - driver 0000818]: Web browsing in Mozilla causes ADAT clocks on HDSP 9652 to be invalid

bugtrack
2005-02-01T21:07:42Z

The following issue has been RESOLVED.
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<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=818>
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Reported By: Mark Knecht
Assigned To: charbonnel
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Project: ALSA - driver
Issue ID: 818
Category: PCI - RME HDSP
Reproducibility: always
Severity: major
Priority: normal
Status: resolved
Distribution: FC2
Kernel Version: 2.6.8.1-1.520.2vS7.ll.rhfc2.ccrma
Resolution: not an issue
Fixed in Version:
======================================================================
Date Submitted: 01-14-2005 18:35 CET
Last Modified: 02-01-2005 22:07 CET
======================================================================
Summary: Web browsing in Mozilla causes ADAT clocks on HDSP
9652 to be invalid
Description:
In my setup I's using 3 computers:

1) PanetCCRMA with HDSP 9652 as the center of an audio hub

2) Win XP GigaStudio with Hammerfall Light - two ADAT outputs streaming to
HDSP 9652 (ADAT input for clock)

3) Win XP Pro Tools Digi 002 Rack receiving GigaStudio audio from PC
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2

So the signal flow looks like:

XP Linux XP
GSt ====> HDSP 9652 ====> Pro Tools
<=== (ADAT Clock)

The HDSP 9652 is the master clock for the network. Both XP machine sync to
the HDSP 9652.

When no specific audio apps are running on the Linux box then this
configuration will work for hours if not days with no problems. All audio
data from GSt flows through the HDSP 9652's hardware and the hardware
mixer sends it on to the Pro Tools box. It works perfectly.

When Mozilla is started and I switch from page to page, after a few
minutes I will receive a message on the Pro Tools box that the clock
supplied by the HDSP 9652 was invalid. I can browse the same web pages on
either XP box and I do not corrupt the clocks.
======================================================================

----------------------------------------------------------------------
rlrevell - 02-01-05 22:03
----------------------------------------------------------------------
Mark,

Your problem is not Mozilla per se but the Flash player plugin. It uses
ALSA's OSS emulation.

A guaranteed workaround is to uninstall the Flash plugin. Then mozilla
will *never* touch your audio device. You could set up two browser
configs, one with Flash and one without, and use the Flash free config for
safe browsing while doing audio work.

Or, you could disable ALSA's OSS emulation. You could even map /dev/dsp
to /dev/null, and configure "well behaved" OSS apps use /dev/dsp1. Then
you could browse Flash pages, but Flash would not be able to make sounds
at all.

A side benefit is that you get less annoying ads with Flash removed.

Lee

----------------------------------------------------------------------
charbonnel - 02-01-05 22:07
----------------------------------------------------------------------
When using the hdsp as a clock source on which your whole studio setup is
dependant (without necessarily running an audio application, e.g. when
doing hardware routing and setting the desired sample rate in hdspconf or
through amixer), here are the options to prevent the audio clock to change
:

* make sure no application uses the card with unpredictable sample rate
requirements (don't use it as the default device, don't use it through the
oss emulation layer)

* make sure that if ever applications access the card, they do it at the
required sample rate (this can be done with the plughw device in your
~/.asoundrc file)

* run an audio application at the desired sample rate. when the device is
opened the clock can't be changed by any other app. typical candidates
here allowing you to keep using the card would be sound daemons (esd,
artsd, jack...)

Issue History
Date Modified Username Field Change
======================================================================
01-14-05 18:35 Mark Knecht New Issue
01-14-05 18:35 Mark Knecht Distribution => FC2
01-14-05 18:35 Mark Knecht Kernel Version =>
2.6.8.1-1.520.2vS7.ll.rhfc2.ccrma
02-01-05 21:35 charbonnel Note Added: 0003466
02-01-05 21:46 Mark Knecht Note Added: 0003470
02-01-05 22:03 rlrevell Note Added: 0003471
02-01-05 22:07 charbonnel Status assigned => resolved
02-01-05 22:07 charbonnel Resolution open => not an issue
02-01-05 22:07 charbonnel Note Added: 0003472
======================================================================

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