TBC with digital output (Or: A/D using an AV receiver)

[msgohan]

As I was recently in the market for a better audio-video receiver, I decided to try to find one with a time-base corrector built-in so that I could try passing VHS sources into it and capturing the HDMI output.

I ended up buying a Denon AVR-890 new from an eBay reseller. This is 2010's model, which I chose because Denon keeps removing more analog inputs with each new iteration.

It does seem to live up to the specs sheet's claim of "Built-In Time Base Correction." The chip used for all inputs is the ADV7840. Unfortunately, the HDMI output employs HDCP even when passing in a home recorded tape, but my HDMI card can be made to ignore this. (The chip is also Macrovision-aware and passes it through the analog outputs, but that would seem to be moot for my purposes.)

I'm hooking up the composite output of my VCRs (non-SVHS, please don't berate me too much for that) to the AVR and then the AVR's HDMI output to my AVerTV HD DVR card. As the AVR doesn't convert analog audio, I also have to run audio to the card's analog inputs. Then I capture 480i YUY2 with Ut Video Codec, and correct the audio delay (which seems to be a constant) afterwards.

The problem I'm running into is that the default brightness (at 0) results in video that's too hot, and that setting doesn't go any lower than 0. This isn't an RGB levels issue, as one of the AVR's screens notes that it's putting out YCbCr 4:2:2. I've included images below with AviSynth histograms to show what I'm talking about. From left to right, the first is my JVC VCR from the 2000s running through the ATI 600 USB direct, the second is the same VCR but hooked up through AVR/HDMI, the third is my Sony "VTR" from 1993 through the ATI 600 USB directly, and the fourth is the Sony through AVR/HDMI. Both VCRs are in Edit mode, and Video Stabilization on the JVC is turned off.

Since we're not to post images wider than 850px inline, I've posted the Imageshack thumbnails for easy viewing in the browser and also attached the images in a RAR file in case the external links ever go down. I hope this is okay.








[I neglected to capture this part of the tape the 4th time]

My current solution to correct this is using AviSynth's ColorYUV with gain_y set to negative values, and cont_y set to positive values to try to bring both black and white back into balance.

I'm just wondering if this is the "correct" way to handle it, or is there a better method?

[admin]

This is very interesting. This is the first time I've heard of -- and seen what appears to be proof of! -- a receiver that has a timebase corrector (TBC) that's removing horizontal signal jitter.

There are a lot of variables here. I don't want to draw conclusions early, based off the sample images submitted so far. Many hobbyists would jump to conclusions about softness, signal stability, and other aspects being presented here. Don't do that.

What are the exact model numbers on these VCRs?

You've piqued my curiosity with this thread. Most interesting. Welcome to the site, glad to have you here -- especially when you bring gems like this one to the table. Very nice.

[msgohan]

The front of the Sony states SLV-750HF. The picture on Sony's eSupport site looks nothing like it though. My comment of "VTR" was based on the remote which controls "VTR/TV" but I see the front panel on the machine itself says video cassette recorder.

This image from an auction site is what it looks like.

1273017271-10565-0.jpg

The back of the JVC says it's HR-J693U.

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Answering my own question a bit, I understand now why the documentation for the ColorYUV says "cont" can be used for luma but it doesn't make sense to. Being intended for chroma, it expands from the center. If I'm reading correctly I should be using a combination of "off" and "gain" to correct Y with this filter.

[NJRoadfan]

I got the same remote, came with the circa 1992 SLV-595HF that was purchased new in 1992. The VCR sits in the basement, but the remote has been re-purposed to work with my SuperBeta machine. Whats odd about this machine is that it is also from 1992, but is more stripped down despite its higher model number. The 595/696HF has a Control-S port for editing and a sharpness dial like SuperBetas or even the AG-1980 along with a VU audio meter display. FWIW, the Sony has a much better picture then that JVC.

Useless info from the manual: VTR mode "1" on the remote is the same IR command set as all Betamax machines. Mode "2" is for all Handycams. "3" is for VHS machines, although the 595HF I have can be set to any of the 3 modes using a switch on the front.

[msgohan]

I don't think that's the same remote as I don't see any mode 1-3 switch; just TV/VTR at the top left. The model number is RMT-V130 and some googling indicates that your model came with RMT-V102D. My remote has an Audio Monitor button but it doesn't appear to do anything, at least not during playback.

I love how the dates on these Sonys are YYYY but are limited to a 16-year range (mine is 1993-2008). Nice bit of planned obsolescence there, guys.

[admin]

Took a little longer to reply to this, needed time to read it carefully again...

The ATI card captures are easily more accurate when not run (and therefore not overblown by) the the Denon AVR. It's hard choice between signal correction in the geometry, and signal accuracy in the color. Once that luminance is blown like that, it's pretty much impossible to restore.

A better method would be a better VCR, to avoid need of the Denon. Is that possible? (Of course, that may still require an external TBC for sync.)

I know I'm not directly answering the Avisynth questions. But to me, it's like somebody asking the best way to commit suicide. I'm more inclined to help address the real problem, instead of the symptoms. I'd rather question the need to jump/shoot/hang/pills/whatever.

[msgohan]

Quote:

Originally Posted by admin

Took a little longer to reply to this, needed time to read it carefully again...

No worries there, I've taken so long I'm getting a necro warning! I finally got an upgrade to an HD satellite receiver so I've kept myself busy playing around with that instead.

Quote:

The ATI card captures are easily more accurate when not run (and therefore not overblown by) the the Denon AVR. It's hard choice between signal correction in the geometry, and signal accuracy in the color. Once that luminance is blown like that, it's pretty much impossible to restore.

A better method would be a better VCR, to avoid need of the Denon. Is that possible? (Of course, that may still require an external TBC for sync.)

I know I'm not directly answering the Avisynth questions. But to me, it's like somebody asking the best way to commit suicide. I'm more inclined to help address the real problem, instead of the symptoms. I'd rather question the need to jump/shoot/hang/pills/whatever.

I get what you're saying, but in this case the Avisynth adjustments seem non-destructive. They aren't truly blown-out/clipped, in that they're still within the valid 0-255 Y-range. Just not 16-235.

Squeezing that down and increasing the saturation slightly, I actually feel that the result is better than the ATI capture in the case of the Sony, as there is a hard-clip going on with that ATI cap, visible in the histogram as well as her white dress.

Here is what I get with ColorYUV(off_y=-10,gain_y=2,cont_u=35,cont_v=35):



I've thought about another VCR, but for various reasons (ex. trying to find someone who will ship to Canada; most of my transfers will be home videos where I'll be the only one of us watching who will even see quality issues) I don't feel I can justify adding yet another piece of obsolete tech to my stack.