iPod iPod efficiency in regards to file size

Demon Hunter

macrumors 68020
Original poster
Mar 30, 2004
2,255
38
I remember reading that the iPod gets much better battery life with smaller files... since the files can be cached with less hard disk access. I can't remember what the optimal size was, up to 15 MB maybe?

I'd like to rip my collection in AAC 320kbps, but I don't want to work my mini to death either. Whatcha think?
 

quackattack

macrumors 6502a
Aug 13, 2004
571
0
Boise, ID
dferrara said:
I remember reading that the iPod gets much better battery life with smaller files... since the files can be cached with less hard disk access. I can't remember what the optimal size was, up to 15 MB maybe?

I'd like to rip my collection in AAC 320kbps, but I don't want to work my mini to death either. Whatcha think?
I think you should be fine. The way I understand it is that their is a 32 mb cache. Lossless is the only thing that adds significant stress to it. Sure there are some minor differences before that. But nothing significant.

I welcome other opinions, as I am not completely sure on this. But that is how I understand it.
 

mad jew

Moderator emeritus
Apr 3, 2004
32,194
6
Adelaide, Australia
It makes sense. Smaller song files means you'll fit a relatively larger amount of music in the cache (time-wise as well as space-wise) so the iPod can then go longer between hard drive accesses.
 

admanimal

macrumors 68040
Apr 22, 2005
3,530
2
Also remember that cache does little for you if you like to skip around from song to song a lot. Caching works the best if you play one complete song after another on a playlist.
 

faintember

macrumors 65816
Jun 6, 2005
1,363
0
the ruins of the Cherokee nation
quackattack said:
Lossless is the only thing that adds significant stress to it.
Humm, i never knew that lossless could add stress to the ipod, but if it does i havent noticed it.

All of my audio on my mini is either lossless or raw .aiff, and I get approx. 9ish hours of operation (this includes using the mini as a HD occasionally for file transportation). So i guess this is a pretty normal battery life out in the real world??

Hope this helps..
 

steve_hill4

macrumors 68000
May 15, 2005
1,856
0
NG9, England
Well the quoted battery life is based upon 128kbps aac, (iTunes default), and assumes the user does not access the iPod much during that time and a "reasonable" volume level, not to mention no EQ settings either.

I have no EQ settings, play it bit louder than what apple would go by, encode largely at 256kbps and don't access it too much. When I don't sync to iTunes for a few days, I would say the battery can go for up to 9 or 10 of the quoted 15 hours. If I were to fully test the battery out to its full potential, I think I could get up to 18 hours, (as other tests have confirmed). One of the most common problems people seem to report when they bring them back to our store for other reasons is, "and the battery life doesn't reach what it says". When I ask them if they have done any of those things above to shorten it and if they are topping up the battery or fully charging/discharging, it explains it almost instantly.

Most of the extra power comes from hard drive accesses, so having a 24 Pink Floyd track, (Atom Heart Mother and Echoes spring to mind), won't be any different in power than playing 6, 4 minute tracks I think, what really increases consumption is when you have higher encoding. Because for the same 4 minute track it takes up about 8MB rather than 4MB, it can't store as much in the buffer and so needs to access the drive twice as much.

What is interesting is Sony quoting 40 hours battery life on their HD5. That assumes the user is encoding at 48kbps ATRAC3PLUS. While many argue that this is the same quality as 128kbps mp3, independent tests of all formats at 128kbps have Sony's format running near the bottom, with usually something like ogg winning and aac second. For mp3 I estimate the HD5 goes down to 20-25 hours at most.
 

quackattack

macrumors 6502a
Aug 13, 2004
571
0
Boise, ID
faintember said:
Humm, i never knew that lossless could add stress to the ipod, but if it does i havent noticed it.

All of my audio on my mini is either lossless or raw .aiff, and I get approx. 9ish hours of operation (this includes using the mini as a HD occasionally for file transportation). So i guess this is a pretty normal battery life out in the real world??

Hope this helps..
Well I know lossless is alot more likely to skip. I beleive it has to read it directly from the drive because of the file size. I am assuming this stresses the battery more as well.

But maybe not, based on your experiance.
 

steve_hill4

macrumors 68000
May 15, 2005
1,856
0
NG9, England
quackattack said:
Well I know lossless is alot more likely to skip. I beleive it has to read it directly from the drive because of the file size. I am assuming this stresses the battery more as well.

But maybe not, based on your experiance.
Not quite, I think it would be possible to read chunks of the data, but it obviously leads to hard drive accesses every minute or two. I'm not sure though, after all, I don't think the software would allow this kind of access and would need all of the file in the buffer to play properly. One other guess would be that it fills up that buffer and then effectively streams the rest of the track, (filling up the buffer with exactly the amount being listened to at any one time.

I would be interested to read what exactly happens with lossless raw music files.
 

wwooden

macrumors 68000
Jul 26, 2004
1,996
145
Burlington, VT
faintember said:
Humm, i never knew that lossless could add stress to the ipod, but if it does i havent noticed it.

All of my audio on my mini is either lossless or raw .aiff, and I get approx. 9ish hours of operation (this includes using the mini as a HD occasionally for file transportation). So i guess this is a pretty normal battery life out in the real world??

Hope this helps..
Well, since your 2nd gen iPod mini is supposed to be able to get up to 18 hours of life, I would think are you putting some strain in it when you are only getting 9 hours.