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Published August 1, 2003

 

Apple iPod Technical Brief and Usage Tips

Apple’s iPod has really expanded the market for hard-drive-based portable music players. Major features include storage capacities starting at 5GB, a compact size, fast file transfers (on and off the device), and excellent sound quality for a portable player. Since it’s really a small computer, it’s a fairly complicated device, and this article discusses some of its internals as well as the computer-related aspects of using it. You’ll see a full review of the iPod in September.

Sizing up the portables

There are several other hard-drive-based players on the market right now like Remote Solution's PJB, the Creative Nomad Jukebox Zen, the RCA Lyra, and the Archos Jukebox. Many of these are cheaper on a per-gigabyte basis than the iPod, but none is as small. A good table showing some of these products is at www.kentidwell.com/ipod/. As I write this, the Creative Nomad information covers an obsolete model and the PJB prices are outdated, but the rest of the information is solid.

Looking at this on a gigabyte-per-dollar basis is interesting, but misses the point. The iPod is just barely small enough (2.5" x 4" x 0.8") to carry with you easily, while the other players are too big: the PJB is too long, the Archos too wide and deep. At 3" x 4.5" x 1", the Nomad Zen comes closest, and it is really the only useful competitor to the iPod in the "carry it with you everywhere" market. The iPod is also lighter than its competitors at around seven ounces, versus 10 to 12 for most of the others.

File system

On the inside, a Macintosh iPod is formatted with the HFS+ file system, while the Windows version uses FAT32. What this means in simple terms is that if you plug a Windows iPod into a Windows system, the unit’s hard drive will mount on your system in the same way a regular hard drive does. Similarly, the Mac version looks like a FireWire hard drive to that type of system. Apple’s Mac Software Updater, available from their website, will convert the hard drive inside a Windows iPod to the Mac version. They don’t recommend going the other way, but software like that available at www.the-midfield.com/ipod.aspx will turn a Mac iPod into a Windows one, and some hackers have done the same thing just by reformatting the drive using Linux.

Skip protection

The iPod implements skip protection by putting a 32MB memory buffer in the player. Now, if you’re playing stuff at CD quality, you will burn through 32MB in about three minutes instead of 20. You’d think that the iPod would be fine as long as it could read the hard drive every three minutes but, disappointingly, that turns out not to be the case. The end result is that when playing CD material, the iPod works about as well as a good CD portable, typically surviving a minute or two when jostled before it starts to skip badly. The best theory I’ve seen presented, from www.ipodhacks.com, is that songs larger than the 32MB buffer aren’t actually buffered at all, and are played straight from the hard drive.

Transfer speed

The speeds of current CD-ROM drives and computers allow you to convert a full-length CD into a computer-usable digital form in a couple of minutes. The iPod connects to your computer using a FireWire port, and with this interface you can replace the entire contents of a 10GB iPod in 25 minutes.

Many of the other portable digital-audio devices use USB 1.1 as their interface. This tops out at 12Mbps. At that speed, updating 5GB worth of data is going to take many hours. This was a huge limiting factor that prevented earlier hard-drive systems like Remote Solution’s PJB from ever catching on. Some of the newer products support USB 2.0, which ramps the speed up to 480Mbps to match FireWire capabilities, assuming your computer also has a USB 2.0 port.

Computer-interface software

If you have a matching Apple Macintosh to go with your iPod, life is easy. Use iTunes, organize your music, and off you go.

On the PC it’s a bit messier. The Windows iPods ship with a version of MusicMatch Jukebox, an MP3 and music organization program that’s fairly popular for no reason I have ever been able to fathom. I find the program difficult to navigate, underwhelming in its support for simple features (try to batch convert a bunch of WAV files to MP3 with it), and just thoroughly painful every time I touch it.

Before you install MMJB, when you plug the iPod in it will show up in Windows as a removable media drive. After you complete installing the software and reboot, the iPod only appears to MMJB, preventing other software that might want to look at your iPod from working. Fixing this was my first non-obvious task. If it bothers you, too, get the PortablesPlus interface to the iPod going. Right click on the iPod under Attached Portable Devices and select the Options item. Under the iPod tab, you’ll find two settings you need to change from their defaults. "Automatically launch MUSICMATCH Jukebox on device connection" can be turned off, and "Enable FireWire disk use" must be turned on for software that wants to see the iPod.

Here’s a typical example of why I hate MusicMatch Jukebox: I added 9GB worth of WAV files to the program’s media library and told it to copy them to the iPod. It complained that there wasn’t enough space to hold them all; this was obviously a bogus warning because it was still there when I reduced the transfer to less than 1GB. Regardless, once I overrode the warning it started transferring. After a couple of files, it died. No error message -- it just stopped, for no apparent reason.

My older but reliable computer that I was using for these tests has a Creative Technology Sound Blaster Audigy in it, and I’ve used the FireWire port on that system before to throw dozens of gigabytes worth of information around without a problem. I didn’t know what was happening.

XPlay Windows software for iPod

Finally reaching my level of disgust with MMJB (as I do every couple of years when I try it again to see if things have improved), I tried downloading XPlay from www.mediafour.com/products/xplay/. This $30 program allows Windows computers to use the Windows or Macintosh version of the iPod. Of course it doesn’t work unless you first do the "Enable FireWire disk use" trick I outlined above, but after that I could navigate the program.

XPlay replaces the music library abstraction that many MP3 programs use nowadays with a simple mapping of the iPod interface into the Windows Explorer system. When you double-click on the iPod, it shows the files on its hard drive, and there’s an XPlay Music folder. Go into this folder and you see the Playlist/Artists/Songs/et cetera as folders you can navigate into. Find the music files you want to install on your Windows computer, drag and drop them over to the right area of the iPod, and you’re done. I only encountered one issue with this interface: XPlay seems to sort the file names for you before copying them. Sometimes I had to struggle with the program to get the track order correct when I was copying an album I wanted to play in its regular running order.

The minute I tried copying files over with XPlay, it chugged along copying a dozen or so of them, then came back with "CRC Error." Cyclic Redundancy Check errors mean that some number of the bits were corrupted during the copy. With this program I could eventually fight through that and get all the files on the iPod by doing the copy over again. (MMJB isn’t as smart about picking up from where it left off if a copy aborts.) The nice descriptive error messages XPlay spat out suggested I try a different computer to see if it was more compatible.

With my second system, a more bleeding-edge setup with Creative’s newer Audigy 2 sound card, copying files to the iPod worked flawlessly. The original Audigy was disappointing to me in a number of respects; on the other hand, I’ve been very impressed with the Audigy 2. Its analog and speaker outputs sound as good as any PC sound card I’ve ever heard, far better than the original Audigy. Its price is more reasonable, and the DVD-Audio support is nice as well. I’ve also had good luck with the iPod and the FireWire ports on the $30 (and sometimes even cheaper) Inland u-Connect PCI to IEEE 1394 card. It uses Via’s chipset and works fine on both PCs and older Macs that don’t have a built-in FireWire port.

If you’re comfortable with navigating the Windows Explorer interface to move files around, I’d say spend the extra $30 to buy XPlay and use that instead of MusicMaker Jukebox. This is an essential purchase in order to make the iPod a happy Windows citizen. You’ll need another program to encode music into MP3 if you go that route, but there are plenty of those available for free (like Winamp) that are much better than MMJB as well. One of the things that is nice about the iPod design is that there are some options available in this category. Some other MP3 playback devices ship with proprietary software to load music into the player (which no one has bothered to replicate and improve), so if those programs don’t work well for you, you’re out of luck.

Equalization

The iPod includes a digital equalizer that can come in very handy. There are 21 presets, some labeled with obvious applications (Treble Booster, Bass Reducer) and others with intended musical styles (Hip Hop, Latin, and many others). Going through all of the presets by ear, I was impressed. The way they’re implemented seems clean -- I never got that feeling that the sound has been torn apart and reassembled, which comes with your typical analog EQ box, and the frequency-transition curves were reasonably smooth. Before I went too crazy trying to analyze everything by ear, I found the following essential charts: www.modeemi.fi/~vesas/iPod_Audio.pdf. This guy hooked his iPod up to an Audio Precision test station and graphed each of the EQ settings. The ones I identified by ear as being way too much are clearly shown to be the more extreme settings when you see their graphs. Rock has a +4dB boost at 20Hz and a +3.5dB peak at 20kHz, making it very fat and bright. R&B is even worse, at nearly +6dB at 20Hz and +2.5dB at 20kHz. Even Classical, which on a lot of EQ presets is a fairly benign setting, is +3.5dB at 20Hz and +2.5dB at 20kHz, relative to its lowest point around 1.5kHz.

I did find some settings useful. Electronic is a relatively smooth curve featuring +2dB of boost at 20Hz relative to its average, +1.5dB up at 20kHz, and some shallow dips around 300Hz and 7kHz. Acoustic is also an interesting setting; it’s +3dB at 20Hz, dropping steadily to -0.5dB by 20kHz, but with a big bump around 3-4kHz that pushes the response level back to the 20Hz level again. The boost around 3kHz is similar to what HeadRoom does in their amps with the filter switch that some models (but not the AirHead) include.

Watch out on all the EQ settings when you compare them with flat. In almost every case, the average volume level goes up 1dB to 2dB in addition to the larger boosts in specific spots, so a comparison is always going to make the EQ’d version sound better initially, just because it’s louder. As EQ goes, the digital setup on the iPod is far more useful than most, with its overall clean-filter implementation and the existence of some subtle but useful response nudges. If you’re using a Mac, it’s also possible to tag individual files with their own EQ settings using iTunes, but I haven’t tested this myself.

iPod hacking

I predict that a year from now, as everyone’s warranties expire on this unit, you’ll see an iPod upgrade scene similar to what’s happening with TiVo hacking right now. It should be straightforward to take apart an iPod and swap a 1.8" hard drive with more capacity into it as they become available. The lithium-ion battery on the iPod will eventually die out, holding much less than the ten hours of playtime it offers when it’s new; that could be replaced with a new unit as well. Tom’s Hardware documents an iPod disassembly and shares similar thinking on this subject at www17.tomshardware.com/mobile/20021003/ipod-02.html if you’re curious. It’s also worth noting that Hitachi has already introduced 20GB and 40GB drives in the 1.8" form factor.


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