stuttering WinDVD audio

[sbaldwin]

I have what seems to be a unique problem with the USB-UIRT. First let me say that other than the following problem I'm very happy with the device and have it and girder controlling my whole system. My problem is when watching a DVD the audio stutters every so often. If I unplug the USB-UIRT or disable the USB-UIRT plug-in input device in girder the problem goes away. I'm using a sound blaster live 5.1 with digital I/O add on card and SPDIF out to my stereo receiver. The analog audio is fine only the digital I/O stutters. It seems that the background work between the USB-UIRT and USB hub is briefly interupting the SPDIF bit stream causing the stutter. I've tried everything I can think of.

Moved the sound card to a PCI slot with it's own IRQ
Reloaded the sound card drivers (several different versions)
Ensured DVD Rom IDE controller DMA is enabled and stays in DMA
Reloaded WinDVD
Tried PowerDVD with same result
Uninstalled and reinstalled USB-UIRT
Uninstalled and reinstalled Girder
Relocated USB-UIRT cable away from SPDIF cable (thought it might be an EMI issue)
Disabled all unused devices (serial, parallel, etc)
Have latest motherboard bios update

Nothing changes the problem except unpluging the USB-UIRT or turning it off in girder. I've searched Creative, Girder and this Forum and can't find anyone else with this problem.


My machine is a little dated 1Ghz Celeron on Abit BE6 (Intel BX440 Chipset with integrated USB Hub). ATI Radeon 7000, 192MB Ram, Windows XP Professional with minimal apps installed. With WinDVD running CPU runs at 20 - 30% The device manager shows 10% bandwidth allocated for the USB devices. The USB-UIRT is the only USB device plugged in. Any other ideas would be greatly appreciated! Any way to throttle back the USB bus usage on the USB-UIRT without negative impact to it's functionality?

[jrhees]

sbaldwin,

What I find really strange is how you mentioned that the analog audio is OK -- I assume the analog audio comes from the same sound card???

Anyway, would you say that the problem is consistent enough that you would be able to notice an improvement (but possibly not a total cure)?

-Jon

[sbaldwin]

Jon,
Thanks for the questions. Both the analog and digital audio come from the same sound blaster live card. The analog comes directly from the card. The digital comes from the add-on Digital I/O card that plugs into the sound blaster via internal ribbon cable. The I/O card does not actually plug into a PCI slot it just occupies one of the slots on the back of the PC. Some improvement is certainly a relative term. I'd say if I could make a before and after comparison 50% improvement would be very noticeble. The anomaly is hard to describe. The audio simply hesitates for a brief moment. This happens in no descernable pattern but very consistently. It doesn't matter if the USB-UIRT is idle or is transmitting or receiving anything. If the movie audio is quiet you don't notice the problem. During sound effects, music, speaking, etc. the problem is very evident. The only comparison I can come up with is listening to a CD that has lots of minor scratches in it. The interuption in audio is brief but very repetitive. I thought you might know of a way to adjust the amount of USB activity. If I slow the activity maybe the stuttering will go away. Any other suggestions would certainly also be welcome. Last night I tried plugging a USB webcam in and not the USB-UIRT. With this configuration I had no audio stutter. Not sure how different a web cam and the USB-UIRT are in terms of bus activity. I also found a registry tweak that supposedly reduces the USB bus polling from every 1 msec to every 5 msecs. The USB-UIRT continued to function although not as reliably but still no change in the problem. I'm starting to think the only fix may be a different sound card.
sbaldwin

[jrhees]

sbaldwin,

Please contact me at uirtsupport@earthlink.net and we'll try some long-distance debugging...

-Jon