ipod and dac?

I was talking with a friend of mine at work regarding the issue of hard drive based music sources, and the question came up about fragmentation.

He's a graphic designer and I am a retoucher and all our work is created using Macs with tons of RAM and fast hard drives. Because of the nature of our work we wage a constant battle with disc fragmentation.

However, since the small hard drives used in devices like the iPod just store and play back music, am I correct to assume fragmentation shouldn't be a problem since files are not being written, read, deleted and re-written on a constant basis?

Or, do these devices have the ability to delete music files and have those same spaces/blocks re-written over which could prevent future files from being written contiguously and therefore leave open the possibility of fragmentation down the road?

Thanks.

Disc fragmentation isn't an issue with 2 channel audio playback. Any 7200 rpm HD with a 2Mb buffer can easily handle the task of 2 channel playback at any of the common consumer bit/sampling rates. In a recording studio where multitrack recording/playback is important, than disc upkeep becomes increasingly important. In that enviroment nearly everyone uses a dedicated HD for the music data and defragging is commonly performed. But then again, the playback of 2 audio tracks is trivial compared to the simultaneous playback of 16 tracks and the recording of 8 new tracks (with effects), a task that can be readily handled by hard disk systems.

Thanks for the response Onhwy61.

You mention that fragmentation with 2-channel playback isn't an issue, but what happens to that drive when songs are written, then deleted and other songs are written over the same blocks where the deleted files once resided?

I realize that when a large number of songs are written/downloaded to device like the iPod, they are initially done so in a contiguous fashion. But what happens when songs are deleted from various points in the middle of those large blocks and new ones written/downloaded? I'd imagine those vacant areas of the drive will eventually be written to, and in the case of large sound file not in a contiguous manner. When repeated over and over, fragmentation will eventually occur.

In my field I work with multiple drives and many of my files can exceed a gigabyte. When diagnosing and testing for problems on my drives, the ones that store the large files experience less fragmentation, but take a while to get into a severe state. The drive that always has the most fragmentation is the start up drive which in my case I've counted up to 200,000 miscellaneous small files scattered all over the place. Severe fragmentation can occur in a few months.

Since my computer doesn't support enough RAM to hold an entire file in RAM, we use large fast scratch disks with speeds in the 10,000-15,000 RPM range. Since these disks temporarily hold information and release it once the file is closed, fragmentation isn't an issue with them. However, a small number of invisible files are still written to them. This is something I can see when running a test using a disk utility like Norton's. Since a scratch disk won't incur the level of file residue a storage sevice does, I don't defrag these devices, but instead wipe them of all files.

However, isn't the iPod basically a storage device no different from any hard drive? I'd think a 40GB iPod that can store up to 10,000 songs [according to Apple] is prone to the same negative issues as any hard drive storing thousands of files.

The reason I raise this issue is that I have owned a DirecTivo unit for two years and have noticed hitches, stalls and pixelization while using the navigation tools. This was non-existent for the first 6 months or so, but has increased greatly with time and usage. This has nothing to do with recording a dropped out transmission because of poor dish to satellite viewing at the time, because this is happening on already recorded programs and doesn't happen in the same place twice.

To me an iPod would be similar to a Tivo unit or any other hard drive. They all store data, are read from and re-written to in a permanent manner. Wouldn't they all be vulnerable to fragmentation and eventually need optimization?

Please let me know if I'm completely wrong or just not getting it.

Thanks!
Dean

Can one of you guys explain to a computer illiterate like myself how to get a digital out from an Apple i-book or power book and how to change the sound card?

I have a pretty high end home system. My CD transport went down and I have been using my laptop and i-book in its place. Plugged into my system using the Headphone out split into the stereo inputs of my pre-amp -- which is not a real high quality connection, it sounds amazingly good. Granted, part of it is the supporting components and speakers,
but still...I'm getting a wide sound stage, good imaging, detail, speakers disappear, etc. In *this* system, I can tell the difference between different sample sizes, the difference between MP3 and AAC, etc. I have done experiments. Uncompressed sounds great. The first thing that goes when you compress the music is air. The soundstage shrinks, dynamics are lost, instruments combine and congest, losing space between instruments, the music becomes rooted to the speakers and the
music becomes far less involving. This is anecdotal evidence at its worst, but with uncompressed, I find myself bobbing my head with the music and with compressed, I find myself saying, "this doesn't sound that bad..." But, I am less relaxed, less involved. Surely, not a scientific
study, but that's what I have. I have *not* done the same experiement with Headphones, nor through a car stereo. I would be curious to see.
But, I like having the ability to plug my laptop or i-pod into my home system -- it is great for background music, parties [open a playlist and
let your guests pick the music from your entire collection -- they love it]
and my wife and kids love the simplicity -- plus -- when they use the
computer or i-pod, they're not taking my CD's out. So, even though I
don't use it for critical listening, it would bother me, knowing it would
sound even better, uncompressed. So, for that reason -- and -- because I believe the capacities of these things is going to keep growing,
I am storing my music uncompressed. But -- that's me. I still say that
AAC at 320 kbps is the next best thing to uncompressed and you can store 400 CD's on a 40 Gig i-pod at that sample size. Pretty amazing.