I had ever tried to only capture 15 frames per second (NTSC) for all 4 channels but that's can only reduce the possibility of PCI corruption. Another strange thing is if I capture only 2 channels with 30 frames per second (the total data is equal to the above situation, right?) then everything looks fine. BTW, how should I adjust the PCI latency in BIOS? The higher or lower value is better? Thanks! Regards, Kevin ----- Original Message ----- From: "Matthias Weingart" <v4l@xxxxxxxxxxxxxxxx> To: <video4linux-list@xxxxxxxxxx> Sent: Wednesday, May 22, 2002 3:33 AM Subject: Re: Noise... > On Tue, May 21, 2002 at 04:03:00PM +0200, Justin Schoeman wrote: > > Kevin Liao wrote: > > > Hi, > > > > > > I am using a video capture card with four BT878A and one INTEL PCI bridge on > > > it. Each video input channel is connected to one BT878A respectively. I am > > > trying to capture video data from all four channels and compress them to > > > JPEG files at the same time. But sometimes I will get some annoying line > > > noise (as indicated by red circle in the attached file). Does anyone know > > > it's hardware's or software's issue? Is there anyway to avoid this? Thanks! > > > > > > > This is a PCI problem. The Bt878's are not getting PCI bus access > > quickly enough, and are dropping data. You can try playing with the PCI > > bus latency settings in the bios, or through the module options of later > > versions of bttv. > > Well, but with the option of the module you are only setting the latency of > the Bt878 (right?). If so and you have a IDE oder network card with high > latency settings you have still a problem! > > I have the same problem (but much heavier!) with a bt848a (card=39). I can > only run at 384x288. With higher settings (e.g. 640x480) I have many > white horizontal lines (as above) and after some minutes the computer > gets crazy (gcc do not work, complety hang and so on). > > I have played with setpci (setpci -v -d *:* latency_timer=1) > (I tried all values 0,1,8,30,64,255 and more ...) > changed my cards in the slots (and was able to get the interrupt 5 for > the 848 only! :-) but all that did not help. > > Any idea what I can do to improve it? > replace the grabber card (maybe it is damaged?) > change the board? (currently: Athlon 800, VIA VT8363/8365 [KT133/KM133], 2000) > change the grabber chip? (does a 878 work better as a 848?) > change the VGA card? (the nVidia GeForce2 MX works better as a Riva 128) > change what else (i tried USB webcams, but the results are much worse)? > kernel: 2.4.17xfs and bttv-0.7.92 > > btw. I have the same problems if I run windows. So I guess > it is hardware related (not solveable by software). > > After some days of fiddling I am out of ideas, hope you can get me some hints. > > Matthias > > > > _______________________________________________ > Video4linux-list mailing list > Video4linux-list@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/video4linux-list
