lines on screen when second cam is added on channel

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darkpaw
Posts: 164
Joined: Thu Apr 26, 2007 2:35 am

lines on screen when second cam is added on channel

Post by darkpaw » Fri Oct 06, 2017 8:32 pm

Hello. Using version 1.30.0 on Ubuntu. I have 4 cams running on a generic Conextant 878a 16-port (4 chips). When running only one cam on each /dev/video channel, the image quality is good. But if I add a second cam to any of the channels, I get intermittent lines on some of the horizontals (not a blurry image, think of it more of what it would look like if a digital image was partially pixellated).

Does anyone know what can cause this? The cams are both set at exactly the same capture rate and resolution.

Baylink
Posts: 330
Joined: Sun Jun 19, 2005 3:19 am

Re: lines on screen when second cam is added on channel

Post by Baylink » Sat Oct 07, 2017 2:36 pm

Ah, capture cards. I remember capture cards. :-)

Could your frame rate be too high? It takes a finite amount of time for the video switch in front of the A/D converter to settle. You generally need an entire frame for each switch.

What frame rate are you recording at?

darkpaw
Posts: 164
Joined: Thu Apr 26, 2007 2:35 am

Re: lines on screen when second cam is added on channel

Post by darkpaw » Sat Oct 07, 2017 11:43 pm

Yeah, I'm still old school because I have too much of an investment into analog gear. :) Some day I'll move to digital.

All cams are at 5 FPS analysis, 10 FPS max, and 15 FPS alarm max.

Thanks for the input, it's appreciated.

Baylink
Posts: 330
Joined: Sun Jun 19, 2005 3:19 am

Re: lines on screen when second cam is added on channel

Post by Baylink » Sat Oct 07, 2017 11:56 pm

5 is the recommended rate; I can't imagine that's too fast for 2 cameras.

What happens if you have 2 cameras on one chip, and nothing on the other 3?

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knight-of-ni
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Re: lines on screen when second cam is added on channel

Post by knight-of-ni » Mon Oct 09, 2017 1:09 pm

A screenshot would be very helpful so we all can see exactly what you are talking about.

The root cause of capture card problems typically goes back to not-quite-right driver settings (under modprobe.d) or color palette settings (under zm monitor config). I recommend you search the forum for similar capture card issues. Others have reported similar issues.
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darkpaw
Posts: 164
Joined: Thu Apr 26, 2007 2:35 am

Re: lines on screen when second cam is added on channel

Post by darkpaw » Mon Oct 09, 2017 8:16 pm

Many thanks for the additional input. There's a REALLY good chance that my modprobe isn't correct, but that's the only one I could seem to get working. Here's an example image. The blue lines are the problem: https://ibb.co/fjm6ab

2 cams on the one chip and the other ones shut down make no difference. So the chips do seem to be processing independently of each other correctly.

Here's my modprobe. The commented lines are from other past cards. The current one is the only one I could get working with the generic 16-port card I'm using now.

darkpaw@zm:/etc/modprobe.d$ cat bttv.conf
#options i2c-algo-bit bit_test=1
#options bttv gbuffers=64 card=102,102,102,102,102,102,102,102 radio=0,0,0,0,0,0,0,0 tuner=4,4,4,4,4,4,4,4 chroma_agc=1 combfilter=2 full_luma_range=1 coring=1 autoload=0
#options bttv gbuffers=64 card=102,102,102,102,102,102,102,102 radio=0,0,0,0,0,0,0,0 tuner=4,4,4,4,4,4,4,4 chroma_agc=1 combfilter=2 coring=1
#options bttv gbuffers=64 card=102,102,102,102,102,102,102,102 radio=0,0,0,0,0,0,0,0 tuner=4,4,4,4,4,4,4,4
options bttv gbuffers=64 card=77,77,77,77

darkpaw@zm:/etc/modprobe.d$

darkpaw
Posts: 164
Joined: Thu Apr 26, 2007 2:35 am

Re: lines on screen when second cam is added on channel

Post by darkpaw » Mon Oct 09, 2017 8:21 pm

Something else that I just noticed as well is that the lines appearing are not happening at the same time between the cams sharing the port. One will get lines, and then the other will get lines, or a couple on both at once. There is no consistency to it at all. And it's not continuous. It may go 30 or 40 frames with it perfect on both cams, then it will get a start doing it again.

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