[geeks] DVI -> SDI

[Joshua Boyd]

On Tue, Mar 07, 2006 at 03:57:55PM -0500, Sridhar Ayengar wrote:

> > If you only need SDI instead of HD-SDI (all of the above boxes are
> > HD-SDI), a A to D box should be only a minor quality loss while saving a
> > lot of money.  For HD, the analog converters seem to be only negligably
> > cheaper than the Gefen converter though.
> 
> I need HD-SDI, though.

Normally, when I see SDI without the HD- in front, I assume SD signals.  
 
> > Perhaps if you would say exactly what you want to do?
> 
> A friend of mine gave me an HD-SDI framegrabber.  (Very nice of him.  It 
> wasn't cheap.)  I wanted to use it to turn a computer into an HD Tivo. 
> I have a HDMI coming out of my digital satellite box.

Are you sure that the HDMI isn't encrypted?  If it is you have
approximately no hope of making this work.

What model HD-SDI card did you get?  I've worked a fair amount with the
AJA OEM-HS cards (I'm not sure if there was a retail equivelent).  I
don't actually have any real HD sources at work though.  I'm using
DVDs feeding a Cobalt scaler for my HD source.  Alas, I haven't been
able to make progressive scan output from the DVD player work with my A
to D units, making the scaling look even worse.

Does you cable box not output MPEG2-TS over IEE1394?  It might be far
cheaper just to switch to a digital satalite box that does support that,
not to mention possibly being a higher quality solution.
 
> > I suppose you could always try to build such a device.  It looks like it
> > would be an interested project.
> 
> Hmmm.  How hard would it be to find the chips, I wonder?  I'll start 
> looking for pricing.

Well, I wouldn't call it a simple project to built your own HD-SDI
unit.  I haven't found where to buy TMDS recievers, but I also haven't
tried tremendously hard to do so.  If I were to try harder, I'd either
contact one of my employers suppliers to ask, or I would contact the
open-graphics project to find where they intend to get their TMDS
transmitters from, then contact that supplier about TMDS recievers.
I've seen the number $20 a unit in orders of 10k thrown around, which is
probably absolutely no help.

-- 
Joshua D. Boyd
jdboyd at jdboyd.net
http://www.jdboyd.net/
http://www.joshuaboyd.org/