[PlanetCCRMA] sound card IRQ and crackling sound on F7

[Fernando Lopez-Lezcano]

On Tue, 2007-06-12 at 20:17 -0400, Hector Centeno wrote:
> I found this guide:
> http://www.ibm.com/developerworks/library/l-hw2.html#N10093 (Linux
> hardware stability guide, Part 2) and followed the advice about
> setting the latency. It seems to be working better now but still have
> to test a little bit more. I don't know if the settings discussed in
> that article are still valid for a modern system (well, the article is
> from 2001 but technology changes so fast...). So basically I set the
> latency of all devices to 176 and my sound card to the maximum (248),
> so it can send longer bursts of data without interruptions...

Yes, that's correct (and that articles is still valid, I think I have a
link somewhere in the Planet CCRMA pages). 

> also I set the priority of Csound to 55.

Hmmm, so you are using csound in realtime? Is it using Jack?
-- Fernando


> On 6/12/07, Fernando Lopez-Lezcano <nando@ccrma.stanford.edu> wrote:
> > On Tue, 2007-06-12 at 19:30 -0400, Hector Centeno wrote:
> > > Hi Fernando,
> > >
> > > Thank you for your advice. It says the Audiophile has a latency of 64
> > > which is what it's set at in the BIOS. Should I reduce this?
> >
> > The latency in this context is how many pci cycles can the card use
> > before it has to give up the bus.
> >
> > The point would be to see if there is another card that has that value
> > set very high and then can hog the pci bus itself and starve the
> > soundcard (64 sounds right for a default).
> >
> > -- Fernando
> >
> >
> > > On 6/12/07, Fernando Lopez-Lezcano <nando@ccrma.stanford.edu> wrote:
> > > > On Tue, 2007-06-12 at 16:56 -0400, Hector Centeno wrote:
> > > > > Hi,
> > > > >
> > > > > I'm having problems with my new motherboard (Asus P5B-VM with an Intel
> > > > > Core 2 Duo) and a M-Audio Audiphile PCI audio interface. My problem is
> > > > > mainly with Csound and getting crackling sound on one channel. If I
> > > > > set jack buffers to anything higher than 512x2 the crackling gets
> > > > > worse. I tried switching the card to the other PCI slot (it has only
> > > > > two) and the problem got even worse as I would get crackling audio
> > > > > always. I noticed that both PCI slots are sharing IRQ with other 3
> > > > > devices (usb, video card, libata). In the motherboards manual it says:
> > > > >
> > > > > 1.8.2 Configuring an expansion card
> > > > > After installing the expansion card, configure it by adjusting the
> > > > > software settings.
> > > > > 1. Turn on the system and change the necessary BIOS settings, if any. See
> > > > > Chapter 4 for information on BIOS setup.
> > > > > 2. Assign an IRQ to the card. Refer to the tables on the next page.
> > > > > 3. Install the software drivers for the expansion card.
> > > > >
> > > > > There is no more details about how to perform step 2, Chapter 4 only
> > > > > talks about reserving IRQ for ISA interfaces and in the bios there is
> > > > > no way to manually assign IRQs and it looks like it's something you
> > > > > are supposed to do va software, so I was wondering if anyone knows how
> > > > > to do IRQ assignment in Linux using the CCRMA kernel. With my older
> > > > > motherboard and FC6 it was possible to get the Audiophile to have it's
> > > > > own IRQ and I never had any problems with the audio (until the hard
> > > > > drive controllers in the mobo started to fail and had to replace it).
> > > >
> > > > I would check the pci latency settings just in case that's the problem.
> > > >
> > > > Do a "/sbin/lspci -v" and see what numbers you have for the latency
> > > > parameter for the cards installed (included the video card).
> > > >
> > > > -- Fernando