Bitrate and battery
[206 byte] By [jee] at [2007-11-9 15:52:49] 
What kind of affect does the bitrate or filesize have on the battery length of an ipod. How much quicker does the battery die if the files are encoded at 192 as apposed to 160 or 128. Is it even noticeable?
# 1 Re: Bitrate and battery
The only trick that I'm aware of that affects battery life is song size. If the song is larger than the buffer RAM (32MB I think) then the hard drive has to spin continuously and your battery drains quickly.Kirk at 2007-11-15 17:40:30 >
# 2 Re: Bitrate and battery
The smaller the bitrate, the less the hard disk spins and the longer the battery lasts.saratoga at 2007-11-15 17:41:30 >
# 3 Re: Bitrate and battery
for what it's worth, i tested my full battery life with "normal" usage (no backlight, but some track switching and artist browsing (i have 240 CD's with 100+ artists in my 40 gig iPod) at between 40-50% loudness setting, no eq.) and got about 6.5 hours of life. i use 256aac sized files. a quick and dirty estimate means my average song size is 7.5 megs.i'd be interested to hear other people's average battery life and what bitrate they use.
Skip
SkippyMcHaggis at 2007-11-15 17:42:40 >
# 4 Re: Bitrate and battery
Unless a song is so large it exceeds the buffer size, the bit rate has jack squat to do with battery life. The iPod spins up the drive, transfers the music to RAM and plays back from that. The iPod then spins down the drive. The extra 0.1 second required to load a 8 MB file encoded at 256 kbps instead of a 4 MB file encoded at 128 kbps is insignificant.Kirk at 2007-11-15 17:43:35 >
# 5 Re: Bitrate and battery
true, Kirk. but there's also the issue that every file in my iPod is around 100% larger than 128kbps. so that bit of time actually can have an impact on battery life, because every song takes just that much longer to load...not to be too argumentative, but here's my counter: i use 256aac and i get about 20% less battery life than apple says i would if i used 128aac. my 6.5 hours to apple's 8. i think a 20% (18.75% difference to be exact) is "significant." so there must actually be a "significant" drain on the battery life over that 6.5 hour period of use.
since i tested it using the methods other people have used to reach the 8 hour mark, and only differed in that my bitrate was 256 and theirs was 128, then bitrate must be doing something.
just my thoughts.
Skip
*edit*i said 50% larger when i meant 100% larger...sorry.
SkippyMcHaggis at 2007-11-15 17:44:33 >
# 6 Re: Bitrate and battery
Unless a song is so large it exceeds the buffer size, the bit rate has jack squat to do with battery life. The iPod spins up the drive, transfers the music to RAM and plays back from that. The iPod then spins down the drive. The extra 0.1 second required to load a 8 MB file encoded at 256 kbps instead of a 4 MB file encoded at 128 kbps is insignificant.Kirk, I can see how you've arrived at that conclusion, but that's not quite how the buffer works.The iPod spins up the drive, -fills the buffer with music- and spins down. Filling the buffer with 128k music will provide the iPod with X minutes of music before another spin is needed; a buffer full of 256k music will last for 0.5X minutes, meaning twice as many spins.
I'm sure that could account for your battery life penalty, Skip.
So from Skip's figures, it looks like a 100% increase in bitrate costs roughly 20% of battery life - or, put another way, a 50% decrease in bitrate increases life by ~25%. Worth knowing!
Sam Williams at 2007-11-15 17:45:41 >
# 7 Re: Bitrate and battery
OK, Apple quotes best battery life for songs under 9 MB.http://docs.info.apple.com/article.html?artnum=93318
http://docs.info.apple.com/article.html?artnum=61434
Kirk at 2007-11-15 17:46:45 >
# 8 Re: Bitrate and battery
well tool's salival album at 256 should kill mine.Ochire at 2007-11-15 17:47:38 >
# 9 Re: Bitrate and battery
I have a 2nd Gen.I use a minimum of 192 CBR, and max of VBR 320.
On average I get about 7.5-8.5 hrs. I dont really count.
stasyna at 2007-11-15 17:48:46 >
# 10 Re: Bitrate and battery
The 2nd Generation iPod is really no compairison since they are known to have much longer battery life. :)DarkJC at 2007-11-15 17:49:48 >
# 11 Re: Bitrate and battery
What kind of affect does the bitrate or filesize have on the battery length of an ipod. How much quicker does the battery die if the files are encoded at 192 as apposed to 160 or 128. Is it even noticeable?He asked how much battery we get, what does the model/year of the iPod have to be a deciding factor if he didnt specify.
stasyna at 2007-11-15 17:50:46 >
# 12 Re: Bitrate and battery
I ran a battery test a while back leaving my ipod to continuosly play through 600 songs. Each song was encoded at 128 bitrate with AAC. My ipod died shortly after 8 hours with volume at 50%, no alarms, no backlight, and no browsing or switching. However, when I used my ipod normally, that means browsing, NO backlight, and 50% volume, I get around 6-7 hours.talkingipods at 2007-11-15 17:51:44 >
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