Friday, May 18, 2007

The Big Vista Sweep, Part V

Mind Transfer #3.1: The Alienware DHS-5

Computer: Alienware DHS-5 Media Center 2005 server
Native OS: WIndows MCE 2005 Professional, SP2
Memory: 2 Gig

Hard drive: 320Gig Onboard, 3 Terabyte RAID0 Array offboard.
Extra Devices/Features: Support for most digital memory sticks, high end graphics card/processor, dual Hauppauge NTSC Tuners, dual ATI HDTV Wonder tuners, Realtek 7.1 audio processor. Media Center Vista upgrade reported on in Part IV had one little issue: you couldn't turn the plasma TV off...which lead me into the wonderful world of VESA protocols... sitting down?

Before I begin my little Tale Of Woe, let me identify the cast of characters in this play:

  • The Alienware DHS-5. As you remember, this is the machine that was upgraded from XP MCE to Vista MCE. The upgrade went extremely smoothly, and there were no reported problems. (Well, until I tried to turn the plasma screen on and off and back on again.)
  • An ATI Radeon 9800 Pro graphics card. This was the graphics card that came shipped with the Alienware. Its been modified by Alienware to be passively cooled, in order to keep the noise down on the system.
  • A Sony XBR-900, 42" Plasma Screen. Sony no longer makes plasmas, having thrown all of their XBR production into their LCD technology - so this set is no longer available. In addition, it was one of the first plasma's on the market. I think that this was actually part of the problem.
  • A Gefen DVI Detective. This little $60 device, intended for home entertainment installers, saved me from throwing out my home system out of frustration.
The Symptoms

Once the Vista upgrade was complete - I believed that I was out of the woods. I posted my success story on this blog, and turned the entertainment system off and went to bed. The next evening, when I decided to watch television, the system came on - but the plasma screen was blank. Nothing I did brought it back to life -- I resorted to rebooting the Vista machine (which is in my basement) in order to watch television. Really inconvenient.

The Hunt

I spent a good deal of time hunting down false leads:
  • First assumption: bad graphics driver. I had heard various stories about the Radeon series of graphics cards from ATI and Vista, so I assumed that it was either the driver, or some new setting on the Catalyst control application that comes with the Radeon. I downloaded the new Vista-specific drivers from the ATI site (version 7.4) -- same problem. Although, bonus: the new Catalyst control application allowed me to manually set the pixel size of the displayable area on the screen. (For those of you without plasmas, here's the plasma dirty little secret: overscan. About 5% of the image on a plasma screen falls outside the physical borders of the device, in order to cure certain boundary problems. 99% of people never notice, but if you have a computer hooked up to your plasma, and your application icons fall outside the viewable area - you, uh, notice.)
  • Second assumption: Vista Media Centers "away" mode was getting confused by the plasma being off. This was easily disabled in both VMC itself, and my changing a setting in the registry. It still didn't work, the plasma screen remained blank.
  • Third assumption: Vista's aggressive power management features were getting in the way. This was almost correct and the information I was mining was starting to make some sense - the plasma was informing Vista that it was off, and in order to save power Vista sends a signal to the graphic card to power down. (Turning the plasma off was the equivalent of shutting the lid on a laptop, in that regard.) So, is it possible that the plasma was not informing Vista that it was turned back on...? Well - almost.
The plasma was, indeed, sending a signal to the Vista box. Using a VNC client to log into the media center from a laptop, I was able to observe the Vista "busy mouse icon" start to spin for a second whenever the plasma came on. This indicates that, yes, indeed, Vista was detecting power on mode from the plasma screen. It was just doing the wrong thing.

A check through various Vista Media Center forums, specifically the Australian Vista and XP Media Center Support Forum, revealed that people were experiencing these same symptoms with certain combinations of plasma screens, video switching receivers, HDMI, DVI, VMC and ATI graphics cards. This lead a few people down the "away" path that King Joey pointed me down earlier. Because the combination of machines that were required for this problem to manefest itself was so esoteric, hardly anyone was hitting this issue.

Eff-ing, lucky me.

The Real Problem

Ever wonder how your new operatin system (Linux, OS X, Vista, XP) knows when a laptop display is closed, or what resolution you've set your funky new digital monitor on? In 1989, an industry organization called VESA (Video Electronics Standard Association) was formed to develop protocols for digital display devices to identify themselves and their capabilities to whatever device happened to be connected to it. When you turn your plasma or LCD monitor on, it is the VESA protocol that identifies itself and its display capabilities to your graphics card.

"But wait!" you say. "What if I have a really fancy setup with two, three or even four different display devices! Just like in 24! Won't my computer confuse the VESA announcement from one monitor with the VESA announcements from another monitor?" Good question, rich kid.

Here's the answer: every digital display device has a unique identifier attached to it, called an Electron Device ID (EDID). This number uniquely identifies a specific digital display before announcing its capabilities. So the conversation goes something like this:

Plasma Monitor: "Hi Computer! My EDID is Bob!!!"
Vista: "Hey there, Bob! I'm Vista. How's it hanging?"
PM: "Slightly to the left, Vista!"
Vista & PM: "HaHaHaHa!"
PM: "I kill me!"
Vista: "Yes, that was funny. Tell me Bob, what can you do?"
PM: "Well, I can display 12 resolutions of various color depths, and I have a physical dimension of 1900x1200 pixels!"
Vista: "Let me write that down....ok. Got it. Thanks"
PM: "No problem - well, I'm going to sleep now!"
Vista: "G'night Bob!"

What? Am I anthropomorphizing again? Sorry.

Anyway - certain display devices (especially the earlier implementations, like my Sony plasma screen) incorrectly implemented some of the VESA protocols. In the case of my plasma, the VESA protocol to announce that it is being turned on is probably incorrect. XP was forgiving of that particular error, but Vista - with its overly aggressive power saving features - is not.

So, once Vista instructed the graphics card to power down, it never tells it to power back up again because the plasma screen never issued the correct series of VESA commands when it was turned back on.

The Solution

It is not possible to make Vista relax its stance on power management. For better or worse, you cannot instruct it to simply leave the graphics card on even if there is no device attached to it. Nice.

A little hunting around, tho, lead me to a clever little device used by home theater installation people: the Gefen DVI Detective. Home installers and other professionals often run DVI connections to dozens of devices - turning plasmas on and off a lot can reduce the life of the screen, and simply pulling out a DVI or HDMI cable will send a disconnect signal to whatever the display was connected, which would mess up whatever the installer was trying to do.

Enter Gefen, a manufacture of cables, switches, breakout boxes and other fun gizmos for home entertainment enthusiasts and installers. One of their devices is the DVI Detective - a $60 device that you plug the DVI cable from the display in from one end, and the Vista Media Center in to the other end. When you turn the display on for the first time, the DVI Detective intercepts the signal, remembers the EDID and the display characteristics, and sends the information back out to the Vista Media Center. From that point on, you can just pull the plug on the plasma and the DVI Detective continues to tell the Media Center that the plasma is still connected and on, and everything is fine.

In theory, the VMC never realizes that the plasma has been turned off, and therefore never powers down the graphics card. In theory. In practice... works like a charm. The $60 magic box allowed me to shut my plasma display off with reckless abandon. This solution should also solve similar problems others are having with other display devices, video switchers, video upres devices and DVI-to-HDMI cables.

Mind Transfer #3 is now, officially complete.

So, allow me to revise:

Verdict: Success (amended)
Additional Round-trip Rocket Time for Problem Solving: 12 hours.
Additional Rocket Cost: Gefen DVI Detective ($60)


Anonymous said...

I realize this is an old post, but I just wanted to say effin brilliant! I have been living with this problem for years and finally just got tired of it enough to do some creative Googling, which landed me here.


RocketMan said...

Glad to help, man - even late in the game. ;)

Ross said...

I am having this problem too - but over HDMI. I wonder if DVI detective works for that.

RocketMan said...

Ross - my apologies for the HUGE delay in response here, but what's a year among friends?

You've probably figured it out by now, but yes, the DVI Detective will work - but Gelfin has an HDMI detective as well. With the DVI detective, you will need to put an HDMI-to-DVI dongle on each end, the HDMI detective is straight passthru.

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Anonymous said...

I understand this piece was written more than 3 years ago. So isn't it time for a update that for instance you could say 60 dollars for a box between your "old" videocard with DVI connection and your plasma screen with HDMI is a bit high, because you can buy now a better videocard with a HDMI port for less than 60 dollars.