Date: Wed, 19 Jul 2006 22:19:41 -0700 From: "Frank Jahnke" <jahnke@sonatabio.com> To: <freebsd-multimedia@freebsd.org> Subject: Re: Sound Issue -- Bzzzzt! Message-ID: <004801c6abbc$1af06000$6600a8c0@zinfandel>
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> Thus spake Frank Jahnke (jahnke@sonatabio.com) [19/07/06 12:29]: > : I recently installed a Turtle Beach Santa Cruz card in my FreeBSD box. > : Mostly I use the Gnome media applications, and audio playback gives me a > : loud BZZZT every 20 second or so. Otherwise it seems to work OK. > > Does normal sound continue to work, unchanged, while the buzzing occurs? > i.e Does it sound like the buzzing is an audio overlay, or audio > replacement? When using other audio apps, do you have the same issue? It sounds like a brief interruption in the audio stream (bzzt) and then the audio resumes. I've not used other audio applications yet. I'm just bringing up multimedia, with which I've never bothered before. So there are some teething pains. > > Higher-end sound cards tend to be a bit more sensitive to interference. If > I run my speaker wires to close to my monitor, I can hear a background buzz, > that's always amplified whenever anything graphically intensive is going on. > > Ditto for the HD: unless your sound card is shielded (which it likely > isn't), HD spinups will cause some interference. However, this is generally > extremely quiet, and most people don't notice it, so I doubt this is your > issue. More information is in order, as my configuration is a bit unusual. First, this is off the DVD player, and not the HDs (which also do not turn off so spinup should not be an issue). This happens running an SMP kernel with APIC (not ACPI) turned off, so it was running on a single CPU. That's necessary to run VMware on BSD, which I need to do once in a while. When I removed the sysctl.conf line that increased the vchans to 4 (namely, it was commented out) and rebooted, sound worked fine in this configuration. It did "tick" once in a while, like a small dust speck on an LP record (and much less than a scratch), but the timing was unchanged. That may well be interference. It also disabled audio in the video portion of things. When I reenabled APIC (and hence had two CPUs) the noise went down even further. Resetting vchans to four gives a tick once in a while, but is not too bad. And the video audio stream works again. The machine has the famous MPX Southbridge, which is quirky, to say the least. The card does not share an IRQ with any other device, and it is the only thing in use on the 33MHz/32 bit bus other than the DVD player. Ethernet and the SCSI controller are both on the 64 bit bus, and the machine is lightly loaded. I would still like to sort out the "bzzt." I will be in XP quite a bit over the next week, and some background music would be nice. I'd also just like to understand better what is going on. Frank
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