Proc Amp and IRE - improving video color?

premiumcapture · #1 06-24-2014, 12:28 AM

Just curious, but if I adjust the luminescence with a Proc Amp fed into my DVD Recorder, will IRE from the DVD recorder still be compliant? My TBC-1000 seems to brighten the picture and I want to improve the color/adjust the lighting for best presentation, yet try to keep IRE compliant if possible.

dpalomaki · #2 07-01-2014, 05:08 AM

Without knowing the specifications and capabilities of the proc amp, including internal limiting that might be present, about the way to tell for sure is with a waveform monitor. Some NLEs include this feature.

sanlyn · #3 07-01-2014, 07:50 AM

SignVideo's PA-100 has a luminance meter. But that measures the signal midway between source and recorder. What the recorder does with it is anyone's guess, but at least you know levels are OK at the measurement point.

What's the TBC-1000 for?

premiumcapture · #4 07-01-2014, 09:58 AM

Quote:

Originally Posted by sanlyn

SignVideo's PA-100 has a luminance meter. But that measures the signal midway between source and recorder. What the recorder does with it is anyone's guess, but at least you know levels are OK at the measurement point.

What's the TBC-1000 for?

Just for stabilization from my VCR. I bought the MDR533H/F7 to see how it did but it seems to brighten the signal too much inside the unit, not an overall brightness like a crappy Toshiba VCR but the highlights seem to be blown out.

Black looks grey, and even with BVP or AVT-8710 adjustments it still seems blown out.

premiumcapture · #5 07-01-2014, 10:08 AM

One other cool thing about this DVD recorder - over coaxial it does not detect Macrovision and it seems to correct colors, however it does pick up interference. If there's a way to clean up the interference, then I can take the TBC out of the equation and it will fix the brightness issues.

sanlyn · #6 07-01-2014, 10:27 AM

Don't know what you mean by interference. If you're recording Macrovision VHS or other source, you do need a tbc. Try it in-circuit at the proc amp's input. I've done it that way. Unfortunately if it's VHS, the frame tbc will send a clean signal to any line-level circuit in the recorder, which will see no errors and won't do anything.

All of these proc amps affect the image. I've used both of them, fin ally settled on the AVT-8710, but didn't have the IRE problems you describe. And as it is, I don't record to a DVD-R. Maybe you can give us more detail about the source and how you play it. Some years ago I had some decent retail tapes that I recorded directly to a Panasonic DMR-ES20 with good results, using the PA-100 and AVT with a Panasonic VCR. The PA-100 gave me the corrections I wanted, which were rather mild. So I can't say why you're having major problems. I've used the BVP-4 proc amp as well, with good results.

premiumcapture · #7 07-01-2014, 10:40 AM

Quote:

Originally Posted by sanlyn

Don't know what you mean by interference. If you're recording Macrovision VHS or other source, you do need a tbc. Try it in-circuit at the proc amp's input. I've done it that way. Unfortunately if it's VHS, the frame tbc will send a clean signal to any line-level circuit in the recorder, which will see no errors and won't do anything.

All of these proc amps affect the image. I've used both of them, fin ally settled on the AVT-8710, but didn't have the IRE problems you describe. And as it is, I don't record to a DVD-R. Maybe you can give us more detail about the source and how you play it. Some years ago I had some decent retail tapes that I recorded directly to a Panasonic DMR-ES20 with good results, using the PA-100 and AVT with a Panasonic VCR. The PA-100 gave me the corrections I wanted, which were rather mild. So I can't say why you're having major problems. I've used the BVP-4 proc amp as well, with good results.

Over S-Video/RCA, VHS will trip the Macrovision, but if I use the coaxial tuner from the VCR, it will accept the signal even with Macrovision but there is a bit of herringbone/repetitive interference, so it replaces one issue with another. I have not tried the surge protection coaxial in/outs, so I will see if that makes a difference.

I have both the 8710 and TBC-1000, and prefer the TBC-1000 in most cases, though the 8710 Proc Amp feature is awesome when the device is working correctly. I believe the brightness is not caused by the input of the devices, but more by the recorder unit itself with whatever is being input, which is to say, even if I darken the image to compensate for brightness issues, some details still seem to be blown out.

sanlyn · #8 07-01-2014, 12:40 PM

If thye source plays OK to your TV or to anotyher DVD-R or capture device, I'd suspect the recorder is doing it. There should be a menu for input/output settings that controls IRE settings.

dpalomaki · #9 07-01-2014, 12:41 PM

Many vriables to contol.
Many devices apply video AGC based on the input signal's sync pulse rather than average level. They amplify the signal as necessary to ensure proper sync height. This can result in image brightness changes if the sync was out of spec. (The underlying assumption in this is that the original signal was good, and they are compensating for line losses.)
Depending on the origin of the video the pedistal (set-up) may be 0 or 7.5 IRE. This can effect how blacks and shadows appear on the display system if there is a missmatch.
Applying gamma correction can brighten (or darken) an image mid tones while leaving highlights and blacks relatively untouched. But that is generally beyond the ability of simple 4-control (color, tint, brightness, contract) boxes.
Cleaning up the image sync is the first thing to do.
MacroVision worked in part by fooling a VCR's AGC circuits

.

premiumcapture · #10 07-01-2014, 09:49 PM

The 'black screen' for the magnavox seems somewhat grey, which I assume is the system overbrightening. I figured by toning things down it would fix it but it seems like thats just the way the unit records. Its very good for cable, no blocking on SP, though with VHS it tends to blur slight details, but thats most likely due to the fact that it is a DVD recorder.

dpalomaki · #11 07-02-2014, 05:12 AM

Any chance the Magnavox was made for the Japan market (or other market where analog black is 0 IRE)?

sanlyn · #12 07-02-2014, 06:43 AM

I was about to ask the same thing about IRE settings. But I think that even in Japan, most similar DVD-R's have i/o settings to control IRE in and out.There are playback settings to choose between something like "normal", "lighter", "darker", etc. You can test by recording a short MPEG2, then burn it to DVD disc and copy that recording to a PC, then check the image with a histogram. If it looks normal in the PC, it's the recorder's output IRE that needs adjusting. If black levels are too high, it's the input IRE that needs adjusting (I think the available adjustment on the DVD-R is for output only, but I could be trusting poor memory on that). I don't recall Panasonic DVD-R's using precise numeric IRE settings, but usually the lighter/darker business.

OTOH if you play North American retail NTSC DVD's on that thing and you have the same problem, it's set up for Japan.

premiumcapture · #13 07-02-2014, 10:56 AM

I checked the recorder settings up and down, no such settings for this model. Will post a short clip for you guys to take a look at.

sanlyn · #14 07-02-2014, 01:47 PM

No i/o level controls, huh?. Not surprising. That Magnavox is made by Funai. They also make current models being sold with Toshiba and Panasonic labels. Magnavox itself is a name that no longer really exists, the outfit closed shop and sold the rights to the name years ago. Matter of fact Magnavox never made anything electronic. Basically they were a furniture company in Dickson, TN that packed their "hi-fi" and TV sets with electronics from everybody in sight, including the old Zenith corp.

Oh, well, maybe a sample can tell us more.

dpalomaki · #15 07-03-2014, 11:54 AM

Check http://en.wikipedia.org/wiki/Magnavox for a different take on the Magnavox name and its history.

Like many USA brands from the domestic consumer electronics haydays of the 1950s and before, the name has undergone many and varied ownership changes since the 1960.

The older console TVs, Hi-Fi sets, speakers, and stereos of long-gone days were pieces of furniture with an electronics package inside. Many people (my wife included) hate exposed components, love a piece of furniture to hide it all.

Ah, bring back the good old days with the rosey glow of cathode heaters to cheer up the dark of night!

sanlyn · #16 07-03-2014, 02:22 PM

Thanks for that Wiki info. For a different take on the old Magnavox line of consumer electronics (as opposed to industrial grade stuff from Magnavox Electronic Systems), I got my take from working high school summers with an uncle who owned two radio-tv repair shops. Saw him working on a Magnavox TV circuit board once and noted that the diagrams were in a Zenith manual. Asked him about it and he told me Magnavox didn't make those boards. Used to drive around town fetching parts for him: Sonotone phono pickups and stylus replacements and whatnot, and even replacement TV tuners and CRT tubes. Saw a lot of names on those boxes, but never saw a box that had "Magnavox" on it. Ripped apart a Magnavox console stereo to install the components in a customer's wall unit: RCA amp and FM tuner, Motorola changer, CTX speakers from Paducah, KY. Knerw a cousin fo0m Vanderbilt U. who worked part-time at the Magnavox furniture, assembly, and shipping plants in Dickson and Clarksville.

Be that as it may, I've read numerous posts and articles stating that Magnavox didn't "make" the DVD-R the O.P. is using. It's moot anyway. Nothing better is available new. The best of consumer DVD recorders and players haven't been made for several years. I still have mine from 2002 and 2004. Still working. Plenty of them being sold today on auction sites (one of mine is a refurb from 2007). Tech and customer reviews on today's brand-new DVD recorders are less than enthusiastic. Of course, the O.P. can use whatever he wants.

Quote:

Originally Posted by dpalomaki

Ah, bring back the good old days with the rosey glow of cathode heaters to cheer up the dark of night!

Yep. Had an aunt who left her Stromberg-Carlson FM radio on all night, volume turned down, and used its green tuning eye as a night light.

In high end audio circles the "good old days" are still here. Tube amps galore, and tech shops that rebuild old ones. LP's and turntables, too. You can still buy a brand new Oracle Delphi turntable ($8850 - the SME tonearm will cost you a few grand more) and titanium mod kits for tonearms from Shure and others. Budget stuff, too, for us mere mortals.

premiumcapture · #17 07-03-2014, 09:45 PM

heres a cut at the beginning. i realize that there were at one point better recorders made but i bought this weighing in the fact that while new doesnt mean better in this case, it should last longer and do a decent job. for important stuff i always capture to pc but for commercial tapes that are just for me, its easier just to stick it onto the hard drive this way.

sanlyn · #18 07-04-2014, 08:28 PM

Thanks for the sample. I'm not certain what it demonstrates. There aren't any blown highlights or crushed blacks (the darkest colors are about RGB 6 or 7 and the brightest just barely sneak into RGB 200). If you mean that the warning looks washed out, it's because of low contrast and low saturation, and a slightly elevated gamma. Not unusual for any outboard tbc I've used. It also looks as if there's dot crawl that has been softened by something (the tbc??). What are those logos and warnings supposed to look like, anyway? Those that I see look different on every tape. You can always pump the brights with a proc amp or post-process, or increase saturation, but that won't restore the color dropout from bad tape.

So I'm not sure what to spot here, except that it does present a very noisy capture and choppy fades, neither of which are helped by the relatively low bitrate and which would be very annoying to watch. Noise eats up data bits that could better be used elsewhere.The attached m2v is cleaned up a bit and seems at least more viewable.

premiumcapture · #19 07-04-2014, 08:59 PM

I don't know quite know how to analyze IRE, so I figured it would be something you could tell at any part of the video. I had a tbc-1000 in place because of macrovision, which explains the softening. I figured I would give a DVD recorder a try, but if I am going to end up editing after the fact it doesn't make sense to use when I can just capture.

Follow up:

I just got three (3) pretty much BRAND NEW JVC S7600's, and using the avt 8710 to adjust brightness/contrast, picture looks MUCH better. Not sure if I am selling the other two, but they came almost unused from a college that had them in a tech lab.

lordsmurf · #20 07-19-2014, 04:30 AM

You seem to have a TBC-1000 that softens. Understand that not all of them do -- most TBC-1000s are fine.

None of our TBC-100's have that symptom. The TBC-100 is the heart of every TBC-1000. The TBC is married to a VP-299 distribution amp. Your TBC may actually be fine. Some VP-299s are the cause of the softening, which you can bypass. Instructions for bypass are elsewhere in this forum.

When it come to color correction, I use my eyes. Meters always lie.

Herringbone is almost inherent to coax. There's just too much signal crammed together to not get noise.

I don't see an IRE error. I'd need to see more footage. What I see is a minimally noisy VHS capture from a retail tape.