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Old 04-08-2010, 02:16 PM
Malik Malik is offline
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Default Rockbox: Choosing an audio format to maximize battery life

I've been thinking about converting my music into something that will give me maximum battery life on my Fuze (And a Clip+ in the near future). I've been using aoTuV b5.5-5.7 at -q2 (96 kbps)for nearly a year now. While the music is (just barely) ABX-able, I didn't hear any annoying artifacts.

I'm most interested in Musepack, as it requires less power than both Vorbis and LAME, and it is also gapless. The only problem is a "seeking issue" I came across in a few threads, of which, I am not completely enlightened. The Q3 (90 kbps) setting is easily ABX-able with the presence of the insufferable metallic noise, but it's gone at Q4 (128 Kbps). Still somewhat ABX-able, but I wouldn't be able to tell outside the test.

Or, there's LAME, which I'm not too familiar with. Will these files play gaplessly without having to make alterations in the metadata? Will the difference between LAME and Musepack be negligible? What about the difference between low-bit rate q2 Vorbis files and standard-bit rate (~160 kbps) LAME files? To me, a 1-2 hour decrease in battery is negligible, but I have a feeling Vorbis eats much more than that (even at low bit rates).

Thanks for any help.
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Old 04-08-2010, 02:23 PM
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dfkt dfkt is offline
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I added "Rockbox" to your topic title to narrow it down a bit, since you didn't even mention Rockbox in your post. I assume you're talking about Rockbox on the Sansas, because of Musepack and gapless?

LAME is perfectly gapless on Rockbox. MPC is an outdated codec that compresses pretty well but is rather crude in other aspects (tagging, seeking, etc). Here's some runtime tests to give you an estimate, but it's probably better you test it on your own as well: http://www.rockbox.org/wiki/BatteryRuntime - From my experience FLAC should be handled very efficiently on most Rockbox targets, giving you a good runtime.
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Old 04-08-2010, 03:31 PM
Malik Malik is offline
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Thanks for that link. Yes, I was talking about Rockbox. The results on the page seem highly variable, so I'll just do my own benching. Though it is clear that FLAC gets the best battery life, my collection is just too large.
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Old 04-08-2010, 04:05 PM
saratoga saratoga is offline
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It won't matter on a Fuze V1, the lowest clock rockbox goes down to on it is 62MHz, and thats way faster then pretty much everything needs, so battery life won't improve with more efficient formats. Eventually this should be fixed like it was for the V2 fuze but its not clear how to do it since the CPU behaves really poorly if the clock is lowered for unknown reasons.


Regarding formats, see:

http://www.rockbox.org/wiki/CodecPer...ew_gcc_results

(scroll down to the fuze part)

test_codec in rockbox is really buggy on the Fuze v1 due to lack of RAM, so only low bitrate (==smaller) files can be benched, but its a good start.
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Old 04-08-2010, 10:07 PM
Malik Malik is offline
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I see. Well, even if that weren't the case (whenever the issue is fixed), the information on that page states that 96kpbs Vorbis runs at 37.39 MHz and 128kbps runs at 39.5 Mhz. I'm not sure if clock speed is the only factor to take into consideration (I'm not sure what the other information means), but perhaps the difference isn't as drastic as I thought. Good, I don't have to re-encode all of my music.
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