The iPod on TV

The new iPod is a great way to watch videos during a morning commute, a lunch break, or a plane trip. But one often overlooked feature is its ability to display those videos on a television set, with the $19 Apple iPod AV Cable. Here’s how to turn your DVDs, as well as the iMovies and recorded TV shows on your Mac, into iPod movies that are destined for television viewing.

Basics and limitations

The fifth-generation iPod supports two video encoding formats: H.264 and MPEG-4. Each of these formats is limited by the number of pixels the iPod can display (the resolution) and the average file size per second of video or audio (the bitrate).

H.264 was designed to produce high-quality video with small file sizes, but it requires a lot of horsepower to decode—consequently, the iPod can play back only H.264 files that have resolutions and bitrates that are lower than those of files in the less-demanding MPEG-4 format.

Apple’s official specs say that H.264-encoded video can have a resolution of up to 320 by 240 pixels and a maximum average bitrate of 768 Kbps, and that MPEG-4 movies can have a higher resolution, 480 by 480 pixels, and a maximum average bitrate of 2,500 Kbps. But these numbers aren’t entirely accurate. While the bitrates are absolute—encoding movies in either format at higher bitrates produces movies the iPod won’t play—the iPod can play movies with higher resolutions. This is because the iPod limits movies not by frame size, but rather by 16-by-16-pixel blocks called macroblocks . The video iPod supports up to 300 macroblocks (76,800 pixels) for H.264 movies and up to 900 macroblocks (230,400 pixels) for MPEG-4 movies. And as long as the iPod can play a file on screen, it can also output the file to a TV.

To calculate the maximum resolution for a movie your iPod can play, follow this formula: (pixel height divided by 16) multiplied by (pixel width divided by 16). If the result is less than 300 for an H.264 movie or less than 900 for an MPEG-4 movie, you’re in business.

The price of quality

The higher the resolution and bitrate, the better the image quality typically is—but cranking up resolution and bitrate also increases file size. For example, Master and Commander, a 2 hour and 18 minute movie, encoded with H.264 at a resolution of 320 by 128 pixels (keeping the wide-screen aspect ratio) and a bitrate of 750 Kbps, weighs in at 890MB. That same movie encoded as a 720-by-304-pixel MPEG-4 file at 2,500 Kbps consumes a whopping 1.64GB of disk space.

On the positive side, MPEG-4 encoding takes less time than H.264 encoding. This is particularly true if you’re encoding a movie with Apple’s QuickTime Pro 7 (but it’s also the case with other encoding apps). Even on a fast Power Mac G5, QuickTime Pro can take an entire day to encode a full-length movie in H.264 (because of QuickTime’s multipass encoding), versus the hour or two it takes to encode that same movie in MPEG-4.

Encoding techniques

Although you can configure QuickTime to convert files more quickly (with a single-pass encode), there are several tools that are better for encoding video specifically for the iPod. For files on your hard drive—such as iMovies or TV shows recorded with a Mac-based video recorder—Tyler Loch’s free iSquint and Splasm Software’s $10 Podner are two of the best apps out there. I prefer Podner’s interface, and I like its ability to tag the genre of files before it adds them to iTunes. But either app will let you encode H.264 or MPEG-4 at different sizes and quality levels.

For converting DVDs you own, the free HandBrake makes the process simple but you do need to put some thought into how good you want your movie to look. If you want to balance file size and picture quality, use H.264. If you want the best-looking movies possible, regardless of how much hard-drive space they consume, use MPEG-4.

H.264 DVD Encoding For H.264, choose MP4 File from HandBrake’s File Format pop-up menu, and AVC/H.264 Video/AAC Audio from the Codecs pop-up menu. Select x264 (Baseline Profile) from the Encoder pop-up menu, and enter

740
in the Average Bitrate field (remember, 768 Kbps is the maximum average bitrate, and your movie won’t play if it goes over that average). To optimize your encoding, enable the 2-Pass Encoding option. Then click on the Picture Settings button, make sure the Keep Aspect Ratio option is selected, and use the arrow controls to change the Width setting to 320. For 4:3 content, that’s the best resolution you can achieve. But if the movie is wide-screen, increase the width until the height and width numbers equal as close to 300 macroblocks as possible without going over. Click on the Close button and then click on Rip to encode the video.

MPEG-4 DVD Encoding For MPEG-4, choose MP4 File from the File Format pop-up menu, and MPEG-4 Video/AAC Audio from the Codecs pop-up menu. Select the default FFmpeg setting from the Encoder pop-up menu, and enter

2200
in the Average Bitrate field to get good-looking video that will work with your iPod (depending on the resolution you choose, your video may not need a bitrate that high, and HandBrake will use only what’s necessary). To optimize your encoding, select the 2-Pass Encoding option. Click on the Picture Settings button, leave the Keep Aspect Ratio option enabled, and use the arrow controls to specify 720 in the Width field. Run the formula to see if you’ve exceeded the 900 macroblocks allowed by the iPod for MPEG-4-encoded movies. Adjust as necessary, click on Close, and click on Rip to encode your movie. Now add your encoded movies to iTunes and sync your iPod.

What’s the difference?

The differences between the two codecs aren’t obvious when you watch movies on the iPod—not only because the screen is so small, but also because the iPod scales the picture down to its native resolution of 320 by 240. Differences are clearer when you view those movies on a television or even a computer monitor (see screenshot). Even the highest-quality H.264 movies lack detail and exhibit blocky artifacts and banding in large, dark areas (in scenes shot under water or in fog, for example). MPEG-4 movies ripped at high resolutions and bitrates offer more-distinct pictures, though some artifacts remain.

Looking Good The clarity of this MPEG-4 movie (left) shows the benefits of high resolution and bitrate, in comparison with the smaller yet blurrier H.264 version (right).

Whichever codec you choose, you’ll want to set the TV Out option in the iPod’s Video Settings menu to Ask (rather than On or Off) if you’re going to connect the iPod to a TV often—that way, you won’t have to adjust the setting every time you plug in. And be sure to set the iPod’s Widescreen option to On; this not only prevents the iPod from cutting off both sides of a wide-screen movie or TV show, but also makes blocky encoding artifacts less obvious for all video files.

[ Senior Editor Christopher Breen is the author of The iPod and iTunes Pocket Guide (Peachpit Press, 2005). ]

Apple’s birthday tunes

April 2006 marks Apple’s 30th anniversary. To celebrate, here are Billboard magazine’s top 10 songs of 1976. Click here for an iMix with all but one of these retro tunes (sorry, Wings’ “Silly Love Songs” isn’t available).— Jonathan Seff

1. “Tonight’s the Night,” Rod Stewart
2. “Silly Love Songs,” Wings
3. “Don’t Go Breaking My Heart,” Elton John and Kiki Dee
4. “Disco Lady,” Johnny Taylor
5. “Play That Funky Music,” Wild Cherry
6. “December, 1963 (Oh, What a Night),” Frankie Valli and The Four Seasons
7. “50 Ways to Leave Your Lover,” Paul Simon
8. “Kiss and Say Goodbye,” Manhattans
9. “If You Leave Me Now,” Chicago
10. “Love Hangover,” Diana Ross

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