Quantcast CTB-100 / AVT-8710 SDI mod? - digitalFAQ Forum
  #1  
01-05-2021, 03:03 PM
Mischa Mischa is offline
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I've been lurking around in this forum for some time. Especially in the realm of VHS digitization. But I have been confused regarding the TBC's. If the magic happens in the A/D converter and the FPGA, is there any use for the D/A converter other than providing for another needless conversion in our precious digitization chain?

Is there any reason not to use the digital data that feeds into the encoder (which is in beautiful ITU-R BT.656 spec), and feed it into a SDI serializer like the CLC020?

I'm having a hard time sourcing a CTB-100/AVT-8710 so I have not been able to try this out unfortunately, but I'm curious how this would work out.


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  #2  
01-05-2021, 03:56 PM
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lordsmurf lordsmurf is offline
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Interesting question.

The FPGA is bitlocked, so that hurdle may have to be overcome first. You can't even learn which it is, because the chips have all been sanded (defaced). I'm not sure if you can just stick SDI out in place of the D>A, as it's expecting a D>A. My knowledge in these areas gets thin, but I wish you luck on it.

BTW, I have a green AVT-8710 in the marketplace forum: http://www.digitalfaq.com/forum/marketplace
Also a "clone" (same chipset).

What you don't want is the black AVT-8710, or "black" clones using the same chipsets.

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  #3  
01-05-2021, 07:21 PM
Mischa Mischa is offline
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Quote:
Originally Posted by lordsmurf View Post
The FPGA is bitlocked, so that hurdle may have to be overcome first. You can't even learn which it is, because the chips have all been sanded (defaced). I'm not sure if you can just stick SDI out in place of the D>A, as it's expecting a D>A. My knowledge in these areas gets thin, but I wish you luck on it.
Makes you wonder what the FPGA is doing. Some people argue that it's only being used to set registers, but as you can see on the picture the digital video lines are actually supplied by the FPGA. You should just be to solder the wires to the pins of the chip, so the D>A converter is still there in case it wants to talk to it. Something like this could work very well, and seems easy to solder with the right tools.

Quote:
Originally Posted by lordsmurf View Post
BTW, I have a green AVT-8710 in the marketplace forum: http://www.digitalfaq.com/forum/marketplace
Also a "clone" (same chipset).
Wow. Those got rare and expensive indeed. If I ever get lucky to find one for a reasonable price I'll pick it up. this DIY project also looks very interesting. In the meantime I can play around with the €10 DMR-ES10 to see how it fares.
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01-05-2021, 07:36 PM
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lordsmurf lordsmurf is offline
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Quote:
Some people argue that it's only being used to set registers,
No.

Quote:
the digital video lines are actually supplied by the FPGA.
Yes.

Quote:
Something like this could work very well, and seems easy to solder with the right tools.
Historical value? Sure.
Current value? Not really. You won't be able to track down those components, either easily or at all.

Notice his RAM comment. When Cypress changed RAM, something changed in the AVT-8710. This is why the black units are terrible. While it could be that something changed in the FPGA, it is more likely RAM conflicts. So you can't just willynilly change out components for "the same" (not AT ALL the same) chips. Cypress never fixed this, and ceased TBC production because the chips needed were no longer fabbed (arguably the chips needed quit being available in 2009, seeing as how 2010+ units were flawed). And you can't get at the FPGA because of the bitlock.

The whole "black AVT-8710" issue sucks, but that's what it is. Those units actually cause dropped frames. Ironic, huh? Most black unit buyers learn it the hard way, or just don't pay attention to their captures (ghosting, frame sticking, loss of audio sync, combo thereof).

Quote:
Originally Posted by Mischa View Post
In the meantime I can play around with the €10 DMR-ES10 to see how it fares.
It's not a TBC, but it's good for partial TBC(ish). Add DVK to make it whole. The ES10/15 isn't €10, but more like €100 (~$110), so assuming typo there.

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  #5  
01-06-2021, 01:42 PM
latreche34 latreche34 is offline
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Quote:
Originally Posted by Mischa View Post
I've been lurking around in this forum for some time. Especially in the realm of VHS digitization. But I have been confused regarding the TBC's. If the magic happens in the A/D converter and the FPGA, is there any use for the D/A converter other than providing for another needless conversion in our precious digitization chain?

Is there any reason not to use the digital data that feeds into the encoder (which is in beautiful ITU-R BT.656 spec), and feed it into a SDI serializer like the CLC020?

I'm having a hard time sourcing a CTB-100/AVT-8710 so I have not been able to try this out unfortunately, but I'm curious how this would work out.
Ensemble Designs, Snell & Willcox, Aja and others made such devices already (Y/C+Stereo in -> 12bit ADC -> TBC -> Frame sync -> 24bit Audio embed and 10bit video serilizer -> SDI out), No need to re-invent the wheel, It's just a matter of watching out for one when it pops up online, When I bought my BE75 few years ago it was selling on eBay for around $100, now you're lucky if you can get one for under $500.
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