[PlanetCCRMA] crackling sound on F7 - using Csound in realtime

[Hector Centeno]

ok, now this is getting strange.. changing the PCI latency timer
didn't really make a difference, as soon as I increase the buffers in
Jack (i.e. something higher than 256x2 like for example 512x2 and also
setting the -B -b flags in Csound accordingly) I start getting
crackling on the right channel... but I found that if at the same
time, while Csound is running in realtime (and crackling like crazy),
I start another sound application that uses jack (like Ardour or
Aqualung player) the crackling disappears immediately! If I quit that
jack application without stopping Csound then the sound remains clean.
If I restart Csound (without any other app. running) the crackling
comes back, but if I restart Csound without closing the other jack
app. then Csound is clean! It's like the presence of another jack app.
at the same time makes Csound to enter in sync with jack properly...
or something like that.


Hector

p.d. I'm forwarding this to the Csound list

On 6/12/07, Fernando Lopez-Lezcano <nando@ccrma.stanford.edu> wrote:
> 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
>
>
>


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