IRQ's: Do they still matter?

[jksmurf]

I am trying to pinpoint my source of dropped frames. It happens on a very regular time interval, every 8 secs approx. (sorry I haven't timed it exactly, it might be less, is there anyway how to time it?) but in between the video is fine. More details on that here:

http://forums.gbpvr.com/showpost.php?p=1...stcount=18

My question is related to IRQ's. In the old days, PC's didn't like IRQ conflicts, these days it doesn't "seem" to be a problem, but I found that if I let the computer assign them autmatically, it gives many cards the same IRQ. Refer attached assignments by my PC.

Could this be a potential source of this "regular dropped frames" issue, with one card on the bus demanding time away from another card?

k.
[EDIT1] http://support.microsoft.com/kb/314068/EN-US/ I do not fancy having to reinstall Windows XP ... the HAL thingy sounds scary...
[EDIT2] http://www.anandtech.com/guides/viewfaq.aspx?i=47 All about IRQ assignments in WinXP
[EDIT3] http://www.anandtech.com/guides/viewfaq.aspx?i=2 In win98 ANY Creative SB Card was apparently a monster

[sub]

IRQ's: Do they still matter?

I dont think there is an definitive answer to that question, but until very recently PVR250/350 cards would stop producing data mid way thru a recording (regardless of app) when it shared an IRQ with another device (which usually ended up being a Creative SB device). It didnt seem to be a problem on the very newest motherboards, but was certainly affecting users with motherboards made two or three years back. I dont think they were coping with the high DMA data volumes that would be generated by these cards. Newer boards seemed to cope much better.

I'm not sure whether any similar problems exist for PVR150s or not.

Given the number and type of devices you're sharing with in that screenshot, I'd certainly be tempted to try to get it to use another IRQ.

[martint123]

And isn't IRQ 9 the odd one on the second PIC (in old style hardware) that is used to daisy chain down to the first controller as IRQ2 ?? - ISTR IRQ 9 could problematical in the old days just on it's own ??

Martin

[daphatty]

I used to have a similar "dropped frames" issue and I found that specifying the third audio option (the one underneath Audio Decoder) actually rectified the issue. It seems that with every PVR build I have done, if I don't specify this option I would get the dropped frame symptom.

IMO, I don't think the problem is your PVRs inability to draw the picture on screen but rather the OS's attempt at keeping the Audio insync with the Video.

[jksmurf]

Cheers daphatty, actually I never know which one of those renderers to choose , so leave it on auto. The Video/Audio are both Nvidia, but oddly the lastgraph doesn't always show the audio codec being Nvidia. (probably a merit thing?)

In any case, as I noted here, http://forums.gbpvr.com/showpost.php?p=1...stcount=36, I can confirm that leaving the downstairs MVP on while trying to play upstairs is the biggest culprit. No more dropped frames with the MVP off (standby), unless I do something like work on the PC while watching a video on the PC).

IF you have a dedicated HTPC the quickest and easiest thing to do is disable in the BIOS devices you do not use, eg. Com ports, printer ports, FDC, etc..

Good idea, but it is unfortunately my main PC too. I have already disabled everything I do not use (com ports, MB USB etc.).

Also, are you using SATA disk drives? There were a lot of reports of these sorts of problems with these drives on early model Mobos.

Nope, with a MB as old as that, I keep everything as old-tech as I can bar the PVR-150 and the Video Card.

Thanks to you both for your recommendations, in any case. I might have a play with the BIOS settings, hopefully I won't stuff it up... :o

k.