I set up our system again on a new installation, all looks about OK but there are some issues now we did not have last time…
Last time I used Video F Linux 2 but this time Video for linux 1 came up with PAL + YUYV automatically, now we seem to be having some quality issues with the video… Some how we we scanning pictures, i.e the pictures seem to refresh from top down slowly, we did not have this last time, same camera's etc…
also when viewing video, the scanning shows up in truncated images and staggered footage…
Is video F Linux 2 better / worse, is there something I am missing, I know the system can produce better images etc and stream better but at the moment it is not...
Odd Scanning view...
Re: Odd Scanning view...
I'm trying to grasp what your trying to explain...
So with V4L1 you get better image/video quality than using V4L2...
You have progressive scanning lines that move from the top of the display and move slowly towards the bottom...
is this a like a black/gray semi striped bar that is maybe about 1/8 the size of the over all video?
And this is happening on the exact same system that didn't previously have that issue?
Typically when I hear this description, I look at the quality of wiring.
Either cheap cables (like premade cables from qsee for example) are terrible quality specially when they are longer than 10 meters. There are premade cables that are good however.
Next I look for the quality of the installation of the connectors on the video feed lines. Should be sold crimped connections with no fraying.
Next I'd look to see if the video feed from the camera is being daisy chained through other equipment or if there are any splitters or Y cables on the feed line as any of these could cause an impedance mismatch.
Last I look at the power source and make sure that it supplies enough current to drive all the cameras that are on it. Also look at what voltage it is supplying, the gage of wire used, and the length of the supply run. The easy way to check is to take a volt meter out to the cams and make sure that you have at least 11.5 volts for 12 volt system for example showing right at the camera. If it is more than a 1 volt drop, either the supply is not rated/supplying enough current for all the devices on it, or the supply line is not a large enough gage for the length of the run.
So if this is happening on the same exact machine and installation where it was not happening before...
I'd be looking towards making sure all the video settings are correct. V4L2 is supposed to be better. Maybe you can install vlc or the like on the machine and check the quality with that as vlc will use the video pass trough method to the screen and display the raw video with very little processing.
So with out the info from the process above, it's really to vague to give a good answer ATM.
From what I think I'm getting from you is this is not the same exact system/location that preformed better before but something you are duplicating, with similar spec's as another system?
So with V4L1 you get better image/video quality than using V4L2...
You have progressive scanning lines that move from the top of the display and move slowly towards the bottom...
is this a like a black/gray semi striped bar that is maybe about 1/8 the size of the over all video?
And this is happening on the exact same system that didn't previously have that issue?
Typically when I hear this description, I look at the quality of wiring.
Either cheap cables (like premade cables from qsee for example) are terrible quality specially when they are longer than 10 meters. There are premade cables that are good however.
Next I look for the quality of the installation of the connectors on the video feed lines. Should be sold crimped connections with no fraying.
Next I'd look to see if the video feed from the camera is being daisy chained through other equipment or if there are any splitters or Y cables on the feed line as any of these could cause an impedance mismatch.
Last I look at the power source and make sure that it supplies enough current to drive all the cameras that are on it. Also look at what voltage it is supplying, the gage of wire used, and the length of the supply run. The easy way to check is to take a volt meter out to the cams and make sure that you have at least 11.5 volts for 12 volt system for example showing right at the camera. If it is more than a 1 volt drop, either the supply is not rated/supplying enough current for all the devices on it, or the supply line is not a large enough gage for the length of the run.
So if this is happening on the same exact machine and installation where it was not happening before...
I'd be looking towards making sure all the video settings are correct. V4L2 is supposed to be better. Maybe you can install vlc or the like on the machine and check the quality with that as vlc will use the video pass trough method to the screen and display the raw video with very little processing.
So with out the info from the process above, it's really to vague to give a good answer ATM.
From what I think I'm getting from you is this is not the same exact system/location that preformed better before but something you are duplicating, with similar spec's as another system?
Re: Odd Scanning view...
Are you using the same settings for your capture card? Or are you letting the system auto detect it?
That could be the problem.
That could be the problem.
Just... enjoy life! 
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mastertheknife
- Posts: 678
- Joined: Wed Dec 16, 2009 4:32 pm
- Location: Israel
Re: Odd Scanning view...
Its not just him. With V4L2 there is a variable that controls this behaviour. To get same effect as V4L1 (progressive image) you need to only capture the odd fields, even fields or both alternately.
With V4L1 you can just set 384x288 for PAL and 320x240 for NSTC and you will get a progressive image. I think with V4L2 to get the same effect you need to capture at 768x576(PAL) or 640x480(NSTC) and set the config fields option to TOP or BOTTOM or ALTERNATE
mastertheknife
With V4L1 you can just set 384x288 for PAL and 320x240 for NSTC and you will get a progressive image. I think with V4L2 to get the same effect you need to capture at 768x576(PAL) or 640x480(NSTC) and set the config fields option to TOP or BOTTOM or ALTERNATE
mastertheknife
Kfir Itzhak.
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tibetfreedom
- Posts: 163
- Joined: Fri Oct 22, 2010 11:21 am
Re: Odd Scanning view...
same settingsDREMA wrote:Are you using the same settings for your capture card? Or are you letting the system auto detect it?
That could be the problem.
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tibetfreedom
- Posts: 163
- Joined: Fri Oct 22, 2010 11:21 am
Re: Odd Scanning view...
I am confused… the camera's are going off all the time but there are no triggers that could be doing that, the images seem to be rippling but that may be an illusion caused by the web viewer… I guess I need to get this sorted out…tibetfreedom wrote:same settingsDREMA wrote:Are you using the same settings for your capture card? Or are you letting the system auto detect it?
That could be the problem.
Thanks…