What is Gapless Playback on the iPod and in iTunes? (Update)

One of the major announcements that Apple made on September 12 was that the latest video iPod (the 5G model) offers gapless playback, and that this feature is available for previous video iPods when updated with the latest firmware. While those who know what gapless playback means embraced this with a loud “Huzzah!”, others are scratching their heads trying to figure out what this means. Here’s an overview of what gapless playback is, how it works, and why you might want it.

Gapless playback is simply the ability for the iPod to play music with no artificial gaps between tracks. For most music, you’ll never notice the difference, but if you listen to operas, dance mixes, or classic progressive rock albums (the standard examples are Pink Floyd’s Dark Side of the Moon or the Beatles’ Sergeant Pepper’s Lonely Hearts Club Band), you’ll hear a jarring half-second space between tracks that are meant to continue seamlessly. This lurch is the audio equivalent of an elevator dropping a floor suddenly, and ruins the listening experience. Fans of live music (The Grateful Dead, and other jambands) especially hate this, since this type of music often has songs that segue from one to another with no break. Finally, Apple answered the call, making the new iPod the only current portable music player that offers gapless playback. (Note: naysayers will point out that the Rio Karma has gapless playback; I said that no current portable music players offer this feature. The Rio Karma is no longer being sold.)

When I wrote about gapless playback here about a year ago, I offered a workaround that would allow classical music fans to rip their music so it could be gapless. The idea was that you simply join tracks when ripping albums, so instead of multiple tracks with numerous hiccoughs, you’d have a single track for an entire work. This is okay, but it’s a workaround; you wouldn’t be able to find which track you were listening to. Now, with gapless playback, operas can have individual tracks, and you won’t heard the difference.

Of course, there’s a down side to this: now classical music fans who did rip their music with joined tracks will probably want to re-rip these discs; I know I’ll be re-ripping all my operas. Sigh.

So how does gapless playback work? You probably noticed that the first time you launched iTunes, the program took a few minutes to analyze your music for gapless playback. iTunes looked at your tracks to determine if there was no silence at their ends to flag them as tracks that would flow smoothly into the following tracks. This works in iTunes, as well as with all 5G iPods and the new iPod nano. However, this does not work with previous iPod models. Curiously, this process works automatically, though there is a “Part of a gapless album” tag that can be set for individual tracks. It’s not clear if this tag exists to turn on gapless playback or to turn it off. Initial reports say it’s not needed for gapless playback (it certainly isn’t needed with iTunes); I’m awaiting a new iPod to test it there and figure out exactly what it’s for. (Yes, I don’t yet own a video iPod.)

Stay tuned for an update to this article in a week or so when I’ve fully figured out how this tag affects playback on the iPod. For now, be happy (if you find gapless playback useful) or yawn if you don’t. I, for one, applaud the fact that Apple listened to its users and provided this needed feature.

Update: Apple has cleared up the question about the gapless tag. They say this tag only matters if you have crossfade playback turned on in iTunes, and it only affects playback from iTunes. All gapless albums are automatically detected and played as such on 5G iPods (video-capable iPods) and 2G iPod nanos (the latest versions of the nano).