I understand why multiples of 2 show up so often in with computers because of their binary nature, but I haven't been able to figure out the most common mp3 bitrates (64kbps, 128kbps, 160kbps, 192kbps, 256kbps, 320kbps, etc.) tend to follow this rule as well. Since mp3s are just sequential encodings of sound waves, why does it matter that each second is represented with a number of kilobits that is divisible by 2? Do music players like iTunes just keep reading the file and reproducing the encoded sound regardless of where the second boundaries are, or do they read the file second by second? In the later case, reading a 256kbps file would require reading slightly fewer pages in memory than a 257kbps file, but the player could always just read in 256-kilobit chunks regardless of them bitrate and just process it gradually, right?
Are mp3s at 128kbps popular just because this is a generally accepted bitrate or do they actually have some advantage over files at 126kbps and 131kbps? (other than a very slight difference in quality/filesize...)