Why aren't TBCs capture cards?

[880]

A time base corrector has an ADC chip to convert the video for processing, yes?

So why does it convert it back to analog before output? Why not have a TBC that sends digital video out? This would avoid another DAC to ADC conversion.

[Ghitulescu]

There are such cards. The only problem is that you can't afford one of them and they are not sold at Billy's bargain shop two blocks away, this is why you haven't yet heard of. And even if you have one of them you still need to sell the second house of yours to get another device that can accept SDI (that's the digital interface for SDTV in the pro field).

[Blue_MiSfit]

Oh c'mon now... SDI capture cards aren't that expensive!

http://www.blackmagic-design.com/pro...cklink/models/

I don't think $300 is too much to ask for that kind of functionality

[Mounir]

300$ is an acceptable price i'd say. What kind of tbc such card has ? (line or full tbc ?)
Also i don't understand what kind of analog input they accept (s-video, composite ?)

On wikipedia they say, i quote:

There are various mod kits for existing DVD players and other devices, which allow a user to add a serial digital interface to these devices.

Source: here

[Ghitulescu]

Any capturing card has a line TBC, but I think the OP referred to full frame TBCs which are not present on cheaper capture cards.

And the 300$ blackmagic Blue_misfit's referring to is only the second half of the story (it converts the SDI input into computer files), yes it's not that expensive, but it's also a newcomer. A BD-player costs today some 75-80€, yet only 2 years ago the cheapest one cost 400-500€. Capturing HDMI is also a cheap job today compared to 2009, yet it will be really an expensive hobby if one needs 1080p (as opposed to 1080i capabilities most HDMI cards offer). And paying 300$ for an interface (1:1) is like paying 300$ to add S/P-DIF in to your computer, or DV-in or whatever 1:1 interface; one doesn't pay for the investment in technology, but for the luxury of having a digital "lossless" bridging device/input.

PS: the prices in EU are much higher than those in the States (also the prices for houses ).

[Mounir]

How do you tweak the brightness,contrast,hue,sat, restore sync amplitude, Eliminates picture jitter with this card? I presume its all via software but its not clear to me

[Ghitulescu]

Which card? The Blackmagic series?
The simple ones have profiles (for colours), the more expensive ones may let you alter the colours, but they don't have, even at 990$ listed price, a full-frame TBC.

[Mounir]

Ok that's what i thought... no full frame tbc

[Ghitulescu]

Originally Posted by 880

A time base corrector has an ADC chip to convert the video for processing, yes?
So why does it convert it back to analog before output? Why not have a TBC that sends digital video out? This would avoid another DAC to ADC conversion.

There is a reason however, why so few capturing cards feature a TBC, even in the pro field.

First of all, the computer entered in the pro field too late for the analog - the pros prefer HW solutions, they are by far more stable than their Windows-based counterparts, and are simpler to service. Adding SoCs valued to at least 1000$ (were are talking about the times when analog tapes were still in use) to capturing cards in the same price range was an expensive useless addition.

Secondly, repeated ADA conversions in the pro field are not that destructive as in the consumer field. Various music effects are done digitally in studios, yet the connections were analog. Many replicating factories did ADA before cutting the disc. Even in the consumer realm, people can copy a CD the analogue way (CDplayer -> CDrecorder) without noticeable loss of quality, sometimes the ADA even improves the sound. Some earlier pro decks that record digitally the video did not have a digital interface.

So, it was too late, not needed, and costly.

http://www.bhphotovideo.com/c/produc...g_and_SDI.html
or the double priced
http://www.canford.co.uk/Products/90...deo-in-and-out

[ChiDragon]

I posted on another forum about using an Denon AV receiver to do this, via HDMI output to an HDMI capture card (at 480i since I don't want any upscaling baked in). The card cost me around $85 I believe, while the receiver was several hundred bought new. The lowest-end in this particular line now sells for $100-200 used, but apart from cost you'd have to consider that it's a power-hungry bulky box. I happened to be in the market for a new AVR so that wasn't a concern for me.

I'm still curious whether smaller video processing devices like the DVDO Edge include any sort of TBC on their analog inputs. I did some reading up on the chips purportedly used in some of them but couldn't find anything beyond vague mentions.

The biggest downside of this setup is that you're limited to the proc amp adjustments that the vendor happens to allow in their menu system.

[880]

Thanks Ghitulescu.