DVI video
helloseth
Posts: 43
I know that the Prop can do VGA video, but the world is moving to digital video.· Even the TV mode will become deprecated in a few more years, once analog TV goes dark.
Is is possible to simply drive a DVI-D monitor?· I presume the prop can't do it directly.· But I know nothing about DVI-D.
Seth
Is is possible to simply drive a DVI-D monitor?· I presume the prop can't do it directly.· But I know nothing about DVI-D.
Seth
Comments
You'll need to have a very high speed parallel bus to drive common DVI (and inclusively HDMI) transmitter chips. The MINIMUM pixel rate supported by DVI is 25.175MHz for a 640x480@60Hz (basically VESA "VGA") picture. To fully utilize the pixel bit depth you'll need a 24-bit RGB bus for pixel levels, and you'll also need to generate the Horizontal and Vertical clocks and DE (data enable) signals to correctly parse the frame.
By "pixel repetition" and "line repetition", you should be able to do a 320x240@60Hz image - but you'll need a ton of RAM to hold an individual line of picture info. If you only use a few of the MSBs for the output signal you could do say a 320x240@60Hz image at 6-bit color depth (2-bit per color about what Windows 3.0 could do - about 63 colors plus black). Each line's active pixels would require 60 (32-bit) Longs (very memory hungry) - and you'd probably need two cogs to manage the whole frame's pixel memory, and the clock generation.
This is all academic though - most DVI/HDMI manufacturers will not sell chips to hobbyists because of HDCP (super annoying – but highly secretive and generally accepted video encryption standard). “They” don’t want the programming manuals for these chips to leak onto the open market – as it would take the challenge out of breaking HDCP for content pirates.
I had once asked the guys at Parallax if they’d consider adding a BT.656 video bus output to the video generator – as a great many analog and digital video encoders accept this format, and it would be easy to “hack” a device that is correctly driving VGA out over a DVI interface – or SDI (serial digital), Component (YPbPr), S-Video, or Composite (etc.). I think it’s a bit beyond what they had planned on doing for the integrated video generator…
Cheers!
-Tim
P.S. My day job is Senior Test Engineer for Anchor Bay Technologies, Inc./DVDO (we make video scalers and chips). -Tim
Post Edited (GreyBox Tim) : 11/30/2006 5:20:26 AM GMT
Tim,
Thanks for the info. I'm new to h/w. I've been programming software for 25+ years, but got and electronics itch.
My question was mainly looking to the future. I get Circuit Cellar and other such magazines, and they have articles re-visiting video generation projects from 20 years ago. The old methods still work, but they update to new MCU's.
But I would expect that 5 years from now, you will have to pay extra for analog input to monitors and maybe even TV's. Or worse still, show ebay for them.
As I understand the HDCP, DVI/hdmi doesn't require it, but can work with it. So a monitor with a DVI/HDMI+HDCP would still be able to display a non-hdcp datastream.
BUT, the existing DVI/HDMI chips all have HDCP features and thus come with lengthy NDA's. So, you can't get there from here.
But, I can take the train (which someone else is driving. Someone with access to the chips and NDA's) ... Someone will need to make a "converter" board which would take a simpler signal and drive a DVI/HDMI display. (Much like there are boards to drive LCD screens from a serial signal.)
Is this correct?
Thanks for your insight.
Seth
Want to bet?
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Chip Gracey
Parallax, Inc.
I don't bet on anything, but look at printers. Dot-matrix printers are still made, but for a very,very niche market. (Multi-part form printing). If you price them, a new okidata dot matrix printer runs more than some color laser printers.
Also look at cameras. Film camera still exist but more and more companies are moving their products to pure digital. Soon, film is for the artsey crowd alone.
Can you go to Circuit City and find a nice tube amplifier for you new-fangled hi-fi system?
How about a turn-table? Sure they are still made, but very small niche. Low selection/high prices.
What is the future for NTSC signals once the analog spectrum goes dark? New camcorders will be full digital soon.
I know if the media companies would love to close the 'analog hole'.
-Phil
As for RGBHV, there is a fairly large movement·to replace RGBHV with·a new connection called "Display-Port" (digital, and this is being advocated by VESA).· And guess what - it'll have HDCP too
Completely agree that analog video is going nowhere yet.· "Analog Hole" my >>a..<< that's just a catch phrase to make the idea of cutting it off easier for stupid people to accept ("a hole is bad - we should plug it! And let's plug it with something digital, because digital is better than analog!" - Aren't we all such obedient sheep, Baaaaa
And·digital CCTV surveilance is picking up some clout.· Having a camera internally encode an MPEG4 stream, then encrypting it so it can't be hijacked, and transmitting it over a shared data bus (for cable count/infrastructure reduction) - has been looked at by most of the big players (Pelco, Sony, Hitachi, Honeywell...).· It just makes sense to go digital there too - less space for the same information, instant data archival with non-record-interrupting footage review, and there are a lot of motion detection related components to the MPEG compression scheme which are attractive to be leveraged for security.· By the way, any current CCTV installations are getting LCDs attached to computers, not the old CRT connected to a time-lapse VCR
While HDCP may not be enabled on DVI outputs - all of the commonly available DVI chips over the last five years do have the functionality of HDCP in the logic.· Yes, you may be able to convince "them" to sell you a batch (100+, not one or two, unless you order a development board and re-work it), but it's not cheap ($10K+ for the parts and then there are licensing agreements too $$$$$).· Thrust me - it's not yet easy to do if you are a tiny start-up or hobbyist.
It may be interesting to embed an HDMI·TMDS trasmitter in the core of a Propeller (I'm just kidding about this Parallax!)...
Post Edited (GreyBox Tim) : 11/30/2006 7:24:46 PM GMT
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Chip Gracey
Parallax, Inc.
How much is a new 3-gun CRT projector? Is it 200 or 300 lbs?
An HDMI transmitter which only outputs 480p or 576p would be kind of complicated to add to a Propeller core·- you'd need to have some basic support for differential signaling (the "DS" in TMDS, and active line equalization depending on the version of HDMI you use).· Plus there's EDID stiff that needs to be supported, and possibly InfoFrames (AVI at least for HDMI, then audio, MPEG, Config, Etc.), Hot-plug detection, down-stream device detection, etc., etc...
It's not something I'd expect to see in a hobyist component (or even an ARM9 for that matter).
-Tim
Post Edited (GreyBox Tim) : 12/1/2006 9:26:00 PM GMT
The issue is that a digital imager only has one resolution, while a CRT has an·"analog" phosphor mesh - so it can do many different resolutions without any fancy lens mechanicals (like Runco's "Cinewide" add-on).
-Tim
Post Edited (GreyBox Tim) : 12/1/2006 9:30:33 PM GMT