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Black and White (B&W) PAL Camera capture problem and fix
The short of this message:
If you try to capture video (using Marvel G200/G400 or G450ETV) from a B&W PAL camera and you are frustrated by the PAL video being detected as SECAM or the capture driver bitchin about the video source/signal being unstable, the problem is not that the input signal is too small, but too large. This can be fixed by putting a 75ohm resistor between the video signal and ground to make it smaller (a 75ohm terminator on a T-piece will also work).
The long:
What follows is a rant on my experiences with various Matrox devices in the past 8 years.
At first I loved Matrox products, I remember spending R2000 (around $200) as a student on a Matrox Millenium to play the EF2000 flight sim.
No wonder when I started working I recommended Matrox products for use in some of our capture applications. The first capture card we got was a Marvel G200 (PAL). I loved the onboard MJPEG and in general had no problem with the card, except in some cases when we tried to capture (custom VfW app) from B&W cameras (large zoom one, pulnix ones, or even small pinhole ones) the driver would complain about the video input source not being PAL. We would also get purple flashes on our PAL video and purple artifacts where a video line went from bright white to darker shades. I could live with these problems, I just restarted the capture a few times and it decided all's OK.
G200's were discontinued, so we got Marvel G400's (I have 5 break-out boxes in case someone needs any (some have tuners, some not)). G400's were pretty much the same deal as G200's in terms of capture, but with newer ones, when the app started up, the PAL video was sometimes detected as SECAM and the whole capture screen went purple. The video source could only be switched to PAL when the camera view was blocked so that a very dark image was displayed.
No more G400's, so now we got G450ETV's. Pity the hardware encoding was gone, but I accepted the compromise. Purple hell! More often than not the card complains about the video source and starts up with purple video. So I started searching the forums (BTW Matrox's own forums suck). All info I found on wrongly detected video signals suggested I either amplify the video or get an (overpriced) time base corrector (TBC). I thought that maybe my 15m 75ohm coax cable degrades the signal, so lets get an amplifier. Found an old video distribution amp and put it in line. Same problems. Time to get out the oscilloscope. I found that the signal was in no way degraded. So the next thing to try was to make the signal smaller - put in a T-piece and connected a 100ohm pot to the one end and the Matrox to the other - voila! Card successfully detects input signal, even when I make it a lot smaller (40ohm setting). Purple flashes are gone. When I take out the resistance and it wrongly detects SECAM, I can put in the resistance and switch to PAL successfully. We still have purple where going from white to black, but the rest is OK. BTW, I tried a Pinnacle DC10+ on the same signal and do not get the purple artifacts, but I must say the software installation and bundle of the DC10+ are pure crap.
I'm happy that my capture now works without problems, but feel more than ever that the newer Matrox capture products are sh!te.
Before my G450ETV troubles I had an earlier nightmare with the RT2500. Got the card to replace a G400, cos I like hardware compression. I was enlightened to find the thing mostly unprogrammable, had to search the MURC newsgroups to realise it will only work with the programs they include, no VfW drivers. Had to also install loads of crap before the Video Tools wanted to install. So I have it sitting on my shelf (with a G550 I bought to use with it), brand new. If anyone is interested in it, please let me know. If you can give me proof of a retail price, you can have this one for half of that and I'll throw in the G550 that goes nicely (???) with it.
I think this is enough for now. Thanks for the great MURC forums.
PS, OT and with no implied loyalty to Matrox: If anyone has info on a rock solid capture card I can get working and program under Linux, please let me know.
If you try to capture video (using Marvel G200/G400 or G450ETV) from a B&W PAL camera and you are frustrated by the PAL video being detected as SECAM or the capture driver bitchin about the video source/signal being unstable, the problem is not that the input signal is too small, but too large. This can be fixed by putting a 75ohm resistor between the video signal and ground to make it smaller (a 75ohm terminator on a T-piece will also work).
The long:
What follows is a rant on my experiences with various Matrox devices in the past 8 years.
At first I loved Matrox products, I remember spending R2000 (around $200) as a student on a Matrox Millenium to play the EF2000 flight sim.
No wonder when I started working I recommended Matrox products for use in some of our capture applications. The first capture card we got was a Marvel G200 (PAL). I loved the onboard MJPEG and in general had no problem with the card, except in some cases when we tried to capture (custom VfW app) from B&W cameras (large zoom one, pulnix ones, or even small pinhole ones) the driver would complain about the video input source not being PAL. We would also get purple flashes on our PAL video and purple artifacts where a video line went from bright white to darker shades. I could live with these problems, I just restarted the capture a few times and it decided all's OK.
G200's were discontinued, so we got Marvel G400's (I have 5 break-out boxes in case someone needs any (some have tuners, some not)). G400's were pretty much the same deal as G200's in terms of capture, but with newer ones, when the app started up, the PAL video was sometimes detected as SECAM and the whole capture screen went purple. The video source could only be switched to PAL when the camera view was blocked so that a very dark image was displayed.
No more G400's, so now we got G450ETV's. Pity the hardware encoding was gone, but I accepted the compromise. Purple hell! More often than not the card complains about the video source and starts up with purple video. So I started searching the forums (BTW Matrox's own forums suck). All info I found on wrongly detected video signals suggested I either amplify the video or get an (overpriced) time base corrector (TBC). I thought that maybe my 15m 75ohm coax cable degrades the signal, so lets get an amplifier. Found an old video distribution amp and put it in line. Same problems. Time to get out the oscilloscope. I found that the signal was in no way degraded. So the next thing to try was to make the signal smaller - put in a T-piece and connected a 100ohm pot to the one end and the Matrox to the other - voila! Card successfully detects input signal, even when I make it a lot smaller (40ohm setting). Purple flashes are gone. When I take out the resistance and it wrongly detects SECAM, I can put in the resistance and switch to PAL successfully. We still have purple where going from white to black, but the rest is OK. BTW, I tried a Pinnacle DC10+ on the same signal and do not get the purple artifacts, but I must say the software installation and bundle of the DC10+ are pure crap.
I'm happy that my capture now works without problems, but feel more than ever that the newer Matrox capture products are sh!te.
Before my G450ETV troubles I had an earlier nightmare with the RT2500. Got the card to replace a G400, cos I like hardware compression. I was enlightened to find the thing mostly unprogrammable, had to search the MURC newsgroups to realise it will only work with the programs they include, no VfW drivers. Had to also install loads of crap before the Video Tools wanted to install. So I have it sitting on my shelf (with a G550 I bought to use with it), brand new. If anyone is interested in it, please let me know. If you can give me proof of a retail price, you can have this one for half of that and I'll throw in the G550 that goes nicely (???) with it.
I think this is enough for now. Thanks for the great MURC forums.
PS, OT and with no implied loyalty to Matrox: If anyone has info on a rock solid capture card I can get working and program under Linux, please let me know.
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