07
Sep
07

excuses

Earlier this year, I built a new computer for music recording and photo editing.  For audio, I installed my cheap-but-good old M-Audio 410 PCI card, not the greatest, but it’s kept me from needing to invest in another interface.  But audio performance was dreadful.  If I didn’t run it with a 2048 sample buffer (over 40ms of delay), dropouts were unacceptable and the driver often crashed. The computer itself is modern and very fast, so there was obviously some other sort of problem.  I went through all the usual suspects – driver updates, IRQ conflicts, etc – but couldn’t find it.  Ultimately, some surfing led me to doubts about the interaction of the modern PCI Express video interface with the PCI bus, and a belief that the video subsystem was stealing cycles and interrupts from PCI, and hence killing audio performance.  I decided I would invest in a PCI Express Firewire card and a new Firewire audio interface whenever I had the money – and that’s a fair bit of money.

So last night, I decided to take another look at it.  Turned out that the soundcard was on IRQ 16… a virtual IRQ assigned by ACPI in Windows.  That meant it could be conflicting with a sub-15 IRQ.  I disabled the serial and parallel ports to free up their IRQs, rebooted, and viola!  I was able to crank the card down to 256 samples, or about 5ms of delay, where it ought to be.  So it was an IRQ conflict after all… I just wasn’t enough of a studly nerd to spot the Windows ACPI hazard. Now I can put off getting a new audio interface until I really need more inputs/have money to buy something extra nice.

The lesson to be learned, though, isn’t technical.  Rather, the lesson is that when I see a problem, I should keep trying to resolve it, rather than making excuses and looking for something/someone to blame.  And this applies to non-technical problems as well.

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