I once had an old iPod with 128kbps MP3 copies of my FLAC library. I reencoded everything as 256kbps AAC audio (double the bitrate) and noticed the battery life

I once had an old iPod with 128kbps MP3 copies of my FLAC library. I reencoded everything as 256kbps AAC audio (double the bitrate) and noticed the battery life went way up. Turns out those devices had better hardware decoding for AAC.