Mac mini-HDTV connection guide

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Pioneer SD-582HD5 rear-projection TV: Rob Griffiths

As part of the detailed look at the Mac mini Core Duo I put together earlier this year, I hooked up the desktop to my high-definition TV. This proved to be more of challenge for me than it might normally be for other users—you see, I’ve got a Pioneer SD-582HD5, a five-year-old three-tube CRT rear projector. The only way to connect it to a Mac mini is via an RGB cable.

Only one problem with that: the television conveys absolutely no information about what resolutions it supports via the RGB cable. So when I fired up the mini after hooking it up to the TV, all I had to show for my effort was a completely scrambled image.

After way too many hours on Google, talking with friends, and experimenting with more hardware in the living room than I care to think about, I managed to get it working to the limits of my television's capabilities. Here’s what I did:

First, I made sure I had the following handy: The mini (obviously); a keyboard, monitor, and mouse I could move into the TV room (I found I needed the monitor to join our wireless network—your setup could be different from mine); a second Mac, preferably a laptop Mac of some sort; network connectivity for both Macs; and a male-to-male RGB cable.

On the mini, I installed DisplayConfigX. (Note that you’ll need the $12 registered version in order for this hint to work. You’ll have to decide if the price is worth the result, but in my case, it clearly was—HD video on the big screen looks great.) This program is the key to success for the whole venture; without it, I’d still be looking at nothing but an out-of-scan-range image.

On the mini, I opened the Sharing System Preferences panel, and made sure Remote Login was checked. Then, I enabled Apple Remote Desktop and clicked the Access Privileges button. On the next screen, I checked the box that reads “VNC viewers may control screen with password,” and entered a password. I checked the box next to my user name in the top left portion of the window; then I clicked OK. This enabled remote control of the mini from the other Mac. To actually control the mini, I installed Chicken of the VNC (CotVNC) on the PowerBook.

Before I unplugged everything to move it to the TV room, I tested the connectivity between the PowerBook and the mini. On the PowerBook, I launched CotVNC and entered the IP address and password for the mini. If you’re following along at home, you should be greeted with the mini's screen on your PowerBook. Next, I opened the Displays System Preferences panel, and set the resolution of the mini to 800X600. This will simply make the VNC connection faster. I shut everything down, and moved the whole setup to the TV room, including the PowerBook.

Now it’s time for the actual connection and configuration. Because of the AirPort connectivity issue at startup mentioned above, I chose to boot once with the monitor attached, get connected to AirPort, and then sleep the system. If your mini connects automatically, you can skip all that.

Making sure my television was turned off, I connected the RGB cable between the mini and the television. On our set, this is a switchable input; there’s a toggle next to the RGB port that I had to flip over to activate the connection.

From the PowerBook, I launched CotVNC and connected to the mini. If you’re doing this yourself, you should now see the 800x600 screen that was set up earlier. From here on, I executed all listed commands on the mini via CotVNC, unless specified otherwise.

I opened Displays in System Preferences looked at the resolutions listed. Now you need to find out what resolutions your HDTV supports. Hopefully this information is in your manual, but if it’s not, searching Google with the model number of your set and available resolutions should produce some meaningful matches. In my case, our Pioneer supports 480i, 480p, and 1080i.

A brief aside on the “i” and “p” settings for the above resolutions. The “i” means interlaced, which means the TV draws every other line on one pass, then goes back on pass two and fills in the missing lines. The “p” means progressive, which draws every line in order. When used for displaying a computer screen, interlaced pictures are horrendously flickery, but when playing video back, you won't notice the interlacing. So for my TV, a 1080i signal would give me the best HD playback, with a usable but flickery computer screen. 480p, on the other hand, would make a beautifully stable, but quite small, computer screen, and lowered quality for HD video. Since I mainly wanted the mini to play back HD clips, I needed to find a way to send a 1080i signal from the mini.

Enter DisplayConfigX. This program lets you tell the Mac to send any sort of video signal you desire to the attached monitor. It does this by installing customized resolution settings directly into the Displays preferences panel, through a special display Overrides directory. When you register, you can create your own settings from scratch, as well as use some predefined higher-quality settings that might work right out of the box. As noted earlier, you’ll need the registered version to make this tip work.

I clicked on the Resolutions tab followed by the plus (+) sign at the lower left to add a new resolution. In the new window that opened, I selected a resolution that matches one my HDTV offers—HDTV 1080i. Clicking the Done button, I saw the new resolution at the bottom of the list. This process can be repeated for any other resolutions your television offers. (I added “SDTV-480p” and “NTSC-480i” to the list.) You can also, if you wish, uncheck any entries in the Resolutions tab that your TV does not offer; this will deactivate those resolutions. I suggest leaving 800x600, or whatever resolution you were currently using, in the list.

Now I clicked on the Install tab, then clicked the Install button. This copied my newly-defined resolutions into the Displays Preferences Panel. At this point, take note of the Uninstall button, and the directions underneath, just in case things go horribly wrong.

To see the new values in the Displays panel, I restarted the mini and then reconnected via CotVNC on the PowerBook and opened the Displays panel.

I turned on my HDTV. (If your experience is like mine, there probably won’t be a picture yet, just distortion patterns.) On the PowerBook, I selected one of the HD resolutions I just installed. My HDTV switched over to the new resolution, giving me a picture—and most importantly, the ability to click the confirmation button to retain the new settings. If you’re using a high resolution such as 1080i, you may find (as I did) that CotVNC can’t refresh quickly enough to show the confirmation button, hence the need to use the mini’s mouse to confirm via the HDTV image.

At this point, I discovered I couldn’t see all of the menubar and Dock or the sides of the screen. This is due to something called overscan, wherein the TV draws those images off the top and bottom of the display. To fix the problem, I re-launched DisplayConfigX and selected the resolution I was using (again, 1080i) from the Resolutions tab. Then I clicked the plus sign again. This brought up the New Resolution screen, with the selected values already completed. I clicked the pop-up at the top of the window, and changed it to Timing; that makes every field on the screen editable. I changed the Front porch (top or left border) and Back porch (bottom or right border) settings for the Vertical and/or Horizontal columns. To make the menubar and Dock visible, for instance, you need to increase the Front and Back Porch values in the Vertical column. In doing this, you also need to change the Active entry, such that the figure in Total doesn’t change. Total is simply Active + Front Porch + Sync + Back Porch. I’ll use my settings as an example, and hopefully that will make this bit clearer.

Here are the default settings for 1080i in DisplayConfigX:

default settings for 1080i in DisplayConfigx

When I worked on my overscan settings, after a few iterations (more on that below), here is what I came out with:

custom settings for 1080i in DisplayConfigx

As you can see, I had to move the Front Porch from 24 to 62, and the Back Porch from 20 to 122. Since these values increased by a total of 140, that amount had to come out of Active, dropping it from 1080 to 940. These are large overscan values, and there’s apparently a service mode hack for my Pioneer that will reduce the overscan. I have not yet tried this, but if I can lower the overscan, I can reduce the porch sizes, giving back more resolution for the picture itself.

How do you find your ideal porch values? Lots of testing and rebooting, in my case. (You can try to use the Test Screen tab in DisplayConfigX to measure how many lines are missing, but I found it too hard to read on the 1080i screen.) The basic process is: duplicate the basic setup, and tweak the porch values a bit. Click OK to add the resolution, then click the Install tab and then the Install button to put the new resolution in the system. Reboot the mini to enable the new resolution, open the Displays System Preferences panel, and select the new resolution.

Once I did all that, I tested the Dock and menubar to see how much of them were visible. Since I missed badly the first time, I returned to DisplayConfigX and repeated the process—duplicating the resolution I just tested, increasing the porch values again (remembering to decrease the Active value by the same amount), saving the resolution, installing the resolution, rebooting, selecting the resolution, and testing. I did three iterations of this before I got the settings basically correct for my set.

Once you’ve got the Dock and the menubar, you’re done. You can try playing some HD videos, and they should look great. Of course, if you haven’t bought a “minijack to Toslink” audio cable, you’ll be listening to the crummy Intel mini’s speaker, but you’re on your own for that one.

If you ever move the mini to another monitor, you (probably) don’t need to worry about losing your display settings. DisplayConfigX stores your custom settings as the values for an unknown monitor. I moved the mini back and forth several times, and never lost my custom setups. You could, however, lose your settings if you connect another unknown monitor, as it seems that OS X keeps only one set of settings for any unknown monitor.

The verdict: Hooking up the mini to an older HDTV set is a bit of a challenge; newer sets don’t pose the same sorts of obstacles. However, if you want to watch HD content on a big screen, it’s worth the effort—Apple's movie trailers never looked so good!

[ Senior Editor Rob Griffiths runs the Mac OS X Hints Web site. ]

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