Originally Posted by TurtleFu
So I use a Sansa Clip+ with Rockbox and I've gotten annoyed with the battery life. The player is great but it is a shor tbattery (which I knew when I bought it).
Apparently though it has a very efficient encoder for FLAC and Ogg files, so using FLAC/Ogg actually increases the battery life.
Most of my music is in MP3 LAME V0, some in AAC from iTunes.
I know FLAC uses up way more storage, so that's out. But I know next to nothing about Ogg. Would it be a viable alternative to convert my music into Ogg? What is the highest quality of Ogg files? How does size/quality ratio compare to MP3? Sorry for asking questions like these again.
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Reading a file without even processing it - just
reading it, already drains battery. The cheaper the storage is, relative to the number of GBs it can hold - the more that reading generally drains. Thus switching from HDD storage to flash storage isn't the only possible jump, but there are different grades of flash storage as well. The faster the flash storage, the less it drains your battery for music playback, but the more expensive that storage will be (per GB).
On HDD-based players (such as the iPod Classic), the reading drains more battery than the processing. On flash-based players, the reading itself drains hardly any battery at all, but the processing becomes the main drainer. The more compressed the music is, the more processing it takes to play, and the more battery it drains. FLAC -8 is more compressed than FLAC -0, therefore FLAC -8 can drain more battery. The older the player is, the more inefficient its processor is bound to be, which means the older player drains more battery than a newer player - to process the same compression level of content off the same kind of storage. If WAV files were taggable in a way that portable players could somehow understand, that would be the lowest processing cost of all, because there'd be nothing to decompress during playback.
So best case scenario with CD quality battery life:
the player's processing chip is fairly new and efficient
the storage is some higher-grade of flash (preferably removable)
the lossless uses as little compression as possible, such as FLAC -0
MP3s are cheap to read and cheap to process, but they're not the best-sounding lossy.
An Ogg file averaging near 320kbps (from the q9 setting) will sound more like the source than any MP3 ever will, but I think Ogg Vorbis also costs more to process than any MP3 of the same size. It's really about how much audible detail you're carrying, per MB. So if storage is very limited, Ogg Vorbis is the most efficient use of that storage. But it might not be the most efficient use of your player's processor. Ogg Vorbis has higher "quality" settings which can push the bitrate toward 500kbps, but then you might as well carry lossless instead. On some players, high quality Ogg Vorbis can drain more battery than FLAC.
You'll just have to experiment to figure out what you can get away with. With fast enough flash storage and a new enough processor, some people (with other players) can get over 15 hours of CD quality playback on a single charge, but that's never going to be better than whatever battery life you'd get with MP3s on the same player. So if the official webpage for your player vaguely says "15 hours" without talking about codecs or bitrates, that's probably going to be with MP3, and any other format would be lower in battery life.