[pomegranate]

Apple states its capacity as 2,500, 5,000 and 10,000 songs for the new model iPod. However, I can't figure out what encoding this is based on. I am ripping my cds into AAC 224, what sort of volume of songs will this result in for the 20GB model?

P

 

[JiPi]

Redid the calculs...

About 2976 songs.

 

[chadbang]

Encoding MP3s at 320kbs an album uses approx 100megs, or 10 albums a gig. So with 20 gigs you should get around 200 albums. As there's usually 10-12 songs an album, that's around 2,400 songs.


I'm wondering why, with a freshly erased and formatted hard drive, my 20 gig drive only shows a capacity of 18.5 gigs?

 

[JiPi]

Quote:

Originally posted by chadbang I'm wondering why, with a freshly erased and formatted hard drive, my 20 gig drive only shows a capacity of 18.5 gigs?

That's normal. Every drive always has a 'usable' portion of it. So if it's sold as a 30GB drive,
you'll probably be able to use like, 28,7GB or so.

 

[chadbang]

I thought something like that JiPi. In the OLD days, I might only be able to use 180 megs of my 200 meg hard drive - and the rest was reserved for system use. But 1.5 GIGS seems like a heck of a lot of space for system use - given the piddly system that runs an iPod! That's why I thought it seemed strange, although I do believe you, JiPi.

 

[blessingx]

For the first two generations of iPod, Apple used 160 kbps MP3 for calculating the amount of songs. For the third gen they starting using 128 kbps AAC. I don't remember what the time length of song though they were using. Probably ~4-5 minutes. You're using a little less than twice the bit rate, so if you want a very rough estimate, half the numbers then add a bit.

After the recent lawsuits against computer makers, I believe Apple has restated the actual MB/GB HD sizes also.

 

[rnd]

Quote:

Originally posted by chadbang I thought something like that JiPi. In the OLD days, I might only be able to use 180 megs of my 200 meg hard drive - and the rest was reserved for system use. But 1.5 GIGS seems like a heck of a lot of space for system use - given the piddly system that runs an iPod! That's why I thought it seemed strange, although I do believe you, JiPi.

I believe it's formatting information that takes up that space. Gigs stated is an unformated capacity. I'm sure the OS is still very small.

 

[pomegranate]

Not sure I follow/agree with your "how many kb in 20gb part and your conversion method. I don't understand properly, but there is a difference between kbits and kbytes and therefore between mbits and mbytes and gbytes, yes? Have you factored this in? As an illustration, I have "Wouldn't It Be Nice" by the Beach Boys encoded in 224kbps AAC. This is 2m25s long and comes out at approx 4.15 Mbytes.
So
4,145,152bytes/145 seconds = 28,587bytes per second

If a Gbyte is 1,073,741,824 (1MB = 1,048,576 bytes, x1024 =1GB), then 20Gb should be 21,474,836,480 bytes (right?)

21,474,836,480/28,587bytes ps = 751,210 (approx.) seconds total theoretical iPod time capacity at 224 AAC
If 1 song = 4 mins = 240 secs
Then song capacity is
751,210/240 = 3,130 songs.

I think my maths are right. More to the point, this "feels" about right to me. I'm not using a massively, uh, massive encoding rate, and I'm sure Apple wouldn't be refering to something stupid like 12kbps MP3 encoding when they say 5000 songs. Do you agree/disagree/follow my logic?

I'd appreciate anyone else's views

P

 

[pomegranate]

D'oh, I saw jipi's first reply and took my time (slow brain) replying. Sorreee.
Thanks everyone else.
P

 

[algo]

the size thing:

historically, hdd manufacturers fudge the size of the drives. they go by '1GB = 1000 MB = 1 000, 000 KB' and so on.

however computers are binary by nature, so 1GB = 1024 MB.

so take a 20GB iPod. they claim it is 20GB but really they mean 20,000,000,000 bytes.

20,000,000,000 / 1024 = 19531250 KB
19531250 / 1024 = 19073.486328125 MB
19073.486328125 / 1024 = 18.626 GB

edit: then there is formatting, but that does not create as huge as a discrepancy

also, a freshly formatted drive will in fact show the 18.626. it is only when data is written to the drive that the way it is formatted effects the size. I believe fat32 stores all information in 32kb clusters? I think that is wrong. anyway, it stores it in X sized clusters. if you have a file that is smaller than X, it still takes up that amount of space. over time, this can prematurely shrink your free space.

 

[GSTom1]

Quote:

Originally posted by chadbang Encoding MP3s at 320kbs an album uses approx 100megs, or 10 albums a gig. So with 20 gigs you should get around 200 albums. As there's usually 10-12 songs an album, that's around 2,400 songs.

A full 80 minute CD encoded at 192 kbs mp3s is around 100 megs so there's no way a CD encoded at 320 kbs can be that low. It should be almost double that, around 150-200 megs per CD.

 

[davei]

Quote:

Originally posted by algo the size thing: historically, hdd manufacturers fudge the size of the drives. they go by '1GB = 1000 MB = 1 000, 000 KB' and so on. however computers are binary by nature, so 1GB = 1024 MB. so take a 20GB iPod. they claim it is 20GB but really they mean 20,000,000,000 bytes. 20,000,000,000 / 1024 = 19531250 KB 19531250 / 1024 = 19073.486328125 MB 19073.486328125 / 1024 = 18.626 GB edit: then there is formatting, but that does not create as huge as a discrepancy also, a freshly formatted drive will in fact show the 18.626. it is only when data is written to the drive that the way it is formatted effects the size. I believe fat32 stores all information in 32kb clusters? I think that is wrong. anyway, it stores it in X sized clusters. if you have a file that is smaller than X, it still takes up that amount of space. over time, this can prematurely shrink your free space.

Correct - if you look almost any major manufacturer computer ad, they usually have fine print stating a GB = 1 billion bytes, formatted capacity may be less, etc. The smallest cluster size with Fat32 is 4kb, so a 100 byte file takes up 4kb. With large drives, the FAT starts getting bigger and bigger as well (but still a miniscule percentage of overall drive size).

A good explanation of the whole HD thing can be found here:

http://www.storagereview.com/guide20...partFAT32.html

 

[davei]

Quote:

Originally posted by GSTom1 A full 80 minute CD encoded at 192 kbs mp3s is around 100 megs so there's no way a CD encoded at 320 kbs can be that low. It should be almost double that, around 150-200 megs per CD.

320kbits/sec = 40kbytes/sec or ~2.4MB/min, 4 minute song = ~10MB, ten songs on one CD = 100MB (if you listen to lots of grindcore like I do, 40 minutes is typical for CD length

A full 80 minutes would be 200MB.

 

[Bionic Gecko]

Quote:

Originally posted by davei 320kbits/sec = 40kbytes/sec or ~2.4MB/min, 4 minute song = ~10MB, ten songs on one CD = 100MB (if you listen to lots of grindcore like I do, 40 minutes is typical for CD length A full 80 minutes would be 200MB.

Bad Religion pumps out 26 minute CD's, so should I say that You can encode albums at 450 kbps Ogg Vorbis and each album will come out ~90MB?

Always assume full CD's when saying things like how many songs you can fit on Y player, otherwise the results come back inaccurate.

 

[blessingx]

CD history (relating indirectly to album size)...

Folklore says that Akio Morita, the founder and chairman of Sony, specified a 74 minute playing time so that the Beethoven Ninth could play without interruption. However, according to Kees Schouhammer-Immink, Philips' top scientist on the team of Sony and Philips engineers which designed the CD (and who is a friend of mine), that story is revisionist fiction. The diameter of the CD was originally specified to be the diagonal dimension of the compact cassette, and was then rounded to an even number. Given the sampling rate, bit depth, error correction and practical optical density at the time, the result was a playing time of 74 minutes. But that isn't particularly sexy, is it?

So maybe we should use consider a full album (didn't look for history of LP size) as 74 minutes.