Calculations: Compression vs Lossless

[noddin0ff]

Just thought I'd share my observations. Obviously I have too much free time today. But this could be helpful for those considering moving their CDs to a hard drive on a large scale.

I'm slowly re-ripping my CD collection to Apple Lossless. I decided to do that instead of FLAC because I'm a Mac person and I don't want to wait for FLAC support. I don't think the numbers would move all that much for a different lossless compression format.

I'm just dumping some numbers out here, for those who're interested.

My CD collection is pretty significant. Based on total playing time the breakdown is

22% Jazz
15% Classical
63% Other (mostly Alt/College Rock)

I originally ripped my entire collection with iTunes AAC encoder, mostly @ 192kbps. The bulk statistics are

758 Albums
9504 Songs
29.3 Days of Music
61.79 Gigabytes (@192kbps)
__________

A few CDs a day, and I've re-ripped most of my Jazz collection and some miscellaneous rock (75% Jazz). The total so far...

160 Albums
1737 Songs
6.1 Days of Music
49.49 Gigabytes

From this I extrapolate that 29.3 days of music that took 62 Gigs @ 192kbps will take up 237 Gigs in Apple Lossless. (29.3/6.1X49.49=237).

OR in simple units for storage on a hard drive.
Apple Lossless uses on average 340Mb/hour music
Apple AAC @192kbps uses about 88Mb/hour
Uncompressed is about 600Mb/hour
_____

I took a guess as to what I'd need for storage before I started and thought I'd need a 250G hard drive to do it. Formatted my 250G hard drive has 233G available space. I might make it, so far my guess is within 4GB of my calculation…but I can't buy any more music! I can see a another drive in my future when prices drop some more. The 250G drive was just over $100, no enclosure.
_____

I also tried to see what the average bit rate of Apple lossless was. It varies a lot (with lower bitrates perhaps associated with slower more melodic music?)

Anyway, on a per track basis I see

60 Songs @ >1000 kbps
305 @ 900-1000
535 @ 800-900
402 @ 700-800
266 @ 600-700
103 @ 500-600
29 @ 400-500
37 @ 300-400

So the sweet spot is in the 800’s. CD’s are 1411kbps.

You can wake up now….

[HAVIC]

noddin0ff, I assume that you have an ipod. Go to www.rockbox.org and you can install their free software on to your ipod and it will support FLAC and many other formats, even ac3. I use their software on my iriver mp3 player and I never looked back to the original software. Far superior to any companies front end program. I would definetly check it out.

[noddin0ff]

Thanks I'll check out the link. Sounds like a good hack. I'm not really much of a portable audio person. I own a second hand 1G iPod Shuffle. Mostly it gets used as a flash drive at work. I'm starting to use it for night listening while I read. I put 3 or 4 cd's in WAV format (it doesn't support Apple Lossless for some reason) and plug in my Senns 570. Sounds nice.

[picklgreen]

Currently on my music server I have in iTunes:

9687 songs, 259.94 gigs all in apple lossless.

[noddin0ff]

Sound about right. I'm still re-ripping to Apple lossless. Today I do Rock Ki-Je. I guess I'm about 2/3 of the way through. I figure if I ever want to convert to flac or something I'll just hook up a couple drives to the Apple Lossless library and let my computer burn itself out for a week or more!

10,400 songs, 32.5 days, 183 GB (about 6300 songs in lossless, the rest a mix of 192 and 250.