Thursday, November 16, 2006

Media Center Mac Mini for My Bedroom? (Part 2)

In Media Center Mac Mini for My Bedroom? (Part 1) I may have gotten the cart before the horse. I was musing about how to record TV on a Mac mini equipped with an add-on TV tuner. I was also pondering how to play that and other digital content back into a new LCD flat-panel TV and sound system, probably via a digital media player that communicates with the Mac over a local area network. But first, I think, I ought to consider what the Mac mini can do videowise, all by itself.

The Mac mini is a bare-bones desktop Mac which you trick out with a monitor, a wired or wireless keyboard, and a wired or wireless mouse. It has a front slot for DVDs and other optical media. You can hook the mini to a flat-panel TV via its DVI port, insert a DVD, and have Apple's Front Row software play the DVD right on the TV screen.

In the setup I have in mind, I expect to route video to the TV with a DVI-to-HDMI cable and 5.1-channel audio to an audio system over a cable plugged into the audio output of the mini. For the video connection, I could also get away with hooking the DVI-to-HDMI adapter which Apple includes with the mini to a DVI-to-DVI cable which I already have on hand. See below for more.

Front Row is media software that is controlled by the Apple Remote shown at left in the picture above, and alternatively by keyboard shortcuts (if your mini has a keyboard). It also plays back home movies, photos, and music files from the mini itself or shared by any computer networked to it. "Apple’s zero-configuration technology, Bonjour, lets Front Row find your content easily," says this review from Macworld.

So far, no call for a keyboard or mouse. But, as this later Macworld review notes, you need these input devices to get everything working to your satisfaction. (That review, by the way mentions "Apple’s forthcoming iTV product [which] better fills this niche by doing away with the computer interface and relying solely on a simple, Front Row-style menu system." I see I'll have to find out more about that iTV product.)

Another Macworld article
tells of one reporter's experiences using the mini as a media center. It's amplified by this further article discussing issues people have run into connecting the mini to an HDTV.

In the first article, the reporter (Christopher Breen) found that "When outfitted with the proper peripherals (and those peripherals are correctly configured) the mini performed as a workable media center as long as its media files were stored on the mini or a hard drive attached to it. As a client tasked with streaming media from another computer, Front Row and the mini have a way to go."

But Breen (in my opinion inexcusably, these days) wasn't using an HDTV! He needed to use Apple's optional DVI-to-video adapter ($19) to hook the mini to his dinosaur non-digital SDTV. He also notes that you need to buy a special adapter to convert the mini's audio output connection to TosLink, the standard for digital optical transmission of audio signals. He says that "Griffin Technology’s $20 XpressCable includes the adapter necessary for the cable to work with the mini’s audio jack." Shame on Apple for not including it with the mini.

Breen found that the dumbed-down 800x600 resolution the mini chose for his TV was fine for DVDs but made ordinary computer graphics "a bit squished and fuzzy." There was also the drawback that the Front Row software gave him no control over the audio volume, though his AV receiver did.

Breen added in Elgato's now-discontinued EyeTV 200 tuner/recorder/playback/editing box and Eye2 software to "watch live TV, record TV programs, create schedules for [TV] recordings, and automatically export those recordings in a format compatible with an iPod with video." This use of the mini as a TiVo-like device worked, but with drawbacks. I'll skip those drawbacks for now.

Breen, by the way, recommends Belkin’s $99 MediaPilot as a combination wireless keyboard/wireless mouse, over Apple's Bluetooth-based equivalents. But the Belkin's software, he says, isn't yet compatible with the new Intel-based Macs. Pah!

Breen tried streaming video from his other Macs to the mini wirelessly via AirPort, with mixed results. Part of the problem was that his Airport signal strength was marginal. But even switching to wired Gigabit Ethernet didn't cure all the woes he encountered, with Front Row refusing to play some of the remote video movie files it should have been able to cope with.

Breen later followed up with this postscript discussing how to obviate some of those drawbacks, summarizable thus: "Despite creating the fastest network possible as well as providing Front Row with the slimmest movies possible, it and iTunes refused to play them unless I created an alias of the original movie, mounted the network volume where that movie resided, and copied the alias to the mini’s Movies folder." The solution: "... movies [i.e., computer movie files] must have their streaming option enabled" by means of a procedure which Breen details.

Even so, streaming video "choked" over anything but a wired Gigabit Ethernet network. A "solid AirPort" wireless network wasn't fast enough. And movies that were "too long," if they also had high bitrates, wouldn't stream even over Gigabit Ethernet.

Now, on to the mini-to-HDTV connection perplexities discussed here. One such perplexity is, of course, that the mini provides (only) a DVI video output. DVI was all the rage on HDTVs a couple of years ago, but it's since been overtaken by HDMI. Both DVI and HDMI are digital connections. They're capable of routing uncompressed digital video signals from a source device such as a DVD player or a Mac mini to a TV. But DVI uses a bigger, clumsier connector and doesn't carry any audio signal whatsoever.

Shame on Apple for not putting HDMI output on the mini, then. In fact, I think I can guarantee that the day after I buy a mini, Steve Jobs will announce an all-new Mac mini, replete with the latest-and-greatest version of HDMI, which happens to be HDMI 1.3, and everything else that it needs to bring Apple front-and-center in the race computer-TV convergence reace. That's probably when the anticipated Apple iTV product (see above) will debut as well.

Anyhow, the current mini requires that you buy a DVI-to-HDMI conversion cable in order to hook it to an HDTV's HDMI input. Or you can get either a DVI-to-DVI cable and a DVI-to-HDMI adapter, or an HDMI-to-HDMI cable with a similar adapter. You can find what you need at reasonable prices at Pacific Custom Cable.

There is also the question of what screen resolution the Mac will use with any given model of HDTV. For example, according to this part of the previously mentioned article in Macworld, with a Panasonic TH-42PX60U 42-inch plasma TV the Mac mini's screen resolution automatically changes to 1,600-by-900 pixels at a refresh rate of 60 Hertz.

The Panasonic TH-42PX60U's native screen resolution is 1024 x 768, a common value in plasma HDTVs. That native resolution is neither of the two standards of HDTV resolution: 1920 x 1080 for 1080i and 1080p, and 1280 x 720 for 720p. The 1600 x 900 of the Mac mini's self-selected output exceeds both 1024 x 768 and 1280 x 720, in both the horizontal and vertical directions. It has the correct widescreen 16:9 aspect ratio (note that 1024 x 768 does not translate to 16:9, so the Panasonic's screen pixels are not actually "square").

But the Mac mini may not actually produce full 1920 x 1080 resolution for input to a true 1080p display. In fact, it's not clear whether the Mac mini will sync to a resolution and refresh rate that your HDTV can handle. If, say, your HDTV can sync to 1080i, 720p, or 480p at 60Hz, then perhaps it cannot sync to what amounts to 900p resolution at 60 Hz. It's unclear whether the mini is smart enough to self-select another resolution/refresh rate in such a case.

You can manually set the mini's Displays preference panel to use a different screen resolution if you like, at the cost of making text either too small to read or too "bloated." This can be done in the Displays panel of System Preferences ... but only if you have a properly sync'ed picture on the screen to begin with.

Macworld found 1600 x 900 just right for both computer use and DVD playback on the Panasonic TH-42PX60U. But there was also a problem with "overscan" — the tendency of almost all TVs to put the top, bottom, and side edges of the image beyond the boundaries of the screen. This has been standard practice since the early days of television, since the image on a picture tube shrinks with age. In the digital era, overscan hides the ofttimes noisy image edges.

But computers want to use every pixel of the screen, so displaying their video on an HDTV can cause problems. Macworld found the mini's Displays preferences to have an option to compensate for overscan. Using it put a black border around the whole image on the Panasonic. A DVD then would not fill the entire screen.

The Macworld article also mentioned the need to use the mini's Displays panel to create a custom color profile for the Panasonic, to keep the metallic color of the Mac's windows from having a pinkish cast.

Here is one of the great things about using a Mac as a video source; I don't think the Macworld article did it justice. The Color tab of the Displays preference panel lets you calibrate your display, thereby creating an ideal profile you can use evermore for that display.

The calibration is fairly easy to do. You are walked through a series of steps in which you use the mouse (or, better still, the arrow and tab keys) to adjust a drawing of a filled-in apple-in-silhouette so it is a neutral shade of gray (i.e., lacking any tinge of color) and has exactly the same lightness or darkness as the area surrounding it. This process of adjusting the renditions of grays, oddly enough, makes sure that all colors, at all brightness levels, look just as they should. I think of this as adjusting the image's color balance, but the correct term is performing a grayscale adjustment.

I find on my MacBook Pro that I get the best results if I temporarily change the screen resolution to its lowest available value, so that the apple shape within its surrounding area is as big as possible.

After a number of these color balance or grayscale adjustment steps — and you may want to back up and repeat some of them to get them all just right — you are next asked to choose a "gamma" value via an adjustable slider. This determines how much contrast the screen image will appear to have. If gamma is too low, the image will look flat and washed out. If too high, the image will be objectionably dim for the most part, with glaring highlights.

Next, you choose a target "white point" — a "color temperature" which determines how yellowish-to-bluish the cast of the overall image will be. Ideally, you'd like the white point to be D65, or 6504 degrees Kelvin. Most HDTVs don't hew to that supposed ideal, for reasons I won't go into here. Often, their best approximation is their so-called "Warm" temperature setting, but color temperature may still vary widely with brightness levels within the image. The Mac calibration I'm currently discussing can compensate for all this — but only, of course, when the Mac itself is being used as the HDTV's video source.

One nice thing about how Apple implements all this calibration stuff is that you are doing it in a separate window on the "computer" screen. In another window you can display, say, a freeze frame from a black & white DVD. As you make all the calibration adjustments, you can immediately see the effect on the DVD image. If, for example, the DVD image looks tinged with a bit of green, you know right away you have made some mistake in the calibration and can correct it accordingly.

That's basically it. At the end of the calibration process, you decide whether or not you want to deny other users of your Mac access to your color profile, and you give your profile a name by which you will thenceforth be able to select it in the Displays panel. End of story.

I'll have more to say on the Mac mini connection in my next installment.

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