Stuttering Sound on Windows

Monday, October 26, 2009 / Posted by Luke Puplett /

An LG LS55 laptop I bought for a family member from eBay had an awful affliction which I seem to have encountered a number of times and is a common condition.

The sound stutters or vibrates, particularly when playing Microsoft encoded sound and video files, WMV, WMA and now Silverlight movies and particularly when the machine is busy or buffering.

I fixed it and so for the sake of helping people googling the symptoms, here’s what I did.

Firstly, I ensured it wasn’t a codec or driver issue. The laptop in question has a C-Media 9880 sound chipset, which is Intel I think and runs under the Microsoft UAA standard. I tried to disable the Xear 3D DSP but its just not possible – its ‘in’ the driver.

Reinstalling Microsoft codecs is a case of downloading and installing Windows Media Player again. Suspecting a conflict with the ATI video card, I used the performance settings of Display in Control Panel to take the hardware acceleration to none and did the same in Windows Media Player.

After a lot of time and with horrible pixellated videos, I still had stuttering, echoey and stretched sound, and I was really sure that it was a hardware conflict.

Also, the mouse pointer would jolt every second when smoothly drawing a circle, even though the CPU was at 4%.

Device manager showed that many devices were hanging off IRQ 15 or 16, and of course I couldn’t change them. The BIOS on this machine is pretty basic, too.

Although the BBC iPlayer was fine, the growth of Silverlight meant that it wouldn’t be long before my uncle would call from Belgium complaining about video playback – I couldn’t let him have it like this.

I tried disabling the parallel port to free up IRQ5 and hoped that Windows would move a device. No joy.

So my only choice was to disable IRQ Steering and take back control of my device allocations. There was some bad advice and warnings out on forums about this but I came across a great article.

I have a friend in the music business and their needs for high-performance and reliable studio computers tells me that if anyone knows how to solve pops and clicks in sounds, it’s the music industry. (my friend now runs an 8-core Mac with 32 gig RAM)

This article from Sound-on-sound magazine was my saviour.

I simply when into Device Manager, right-clicked “Computer” and updated the driver to Standard PC from its current ACPI one. It copied over a new HAL, I rebooted and Windows started back up and happily detected and reinstalled all devices!

My mouse moved quickly, my sound sounds sound and videos are silky smooth. I just have to press the power button when Windows shuts down now, and there’s no standy, but its worth it.

Apparently Vista and Win7 are better at spreading devices across the available interrupts. I just wish that user and computer could work cooperatively when I need to force a device setting and let IRQ Steering work around my needs.

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