Rockbox

For some FLAC files, the playback is glitchy. I get sharp high pitched short noises here and there. The sound artifacts are always exactly the same at the exact same times when I try over and over again. I have tried redownloading the files, deleting them and putting them on my player again, different SD cards. It always has the exact same sound artifacts. On my PC with various playback software, the sound is completely normal. The problems arose on my Xduoo X3, but I tested it with the rockbox simulator on my PC, too, and had the exact same sound artifacts, so it should be independent of my device.

It only happened with a single album for me. When I converted it to wav, the problems were gone (but this isn’t a good solution because then there is no tagging support). When I converted it back to FLAC, it miraculously played back without any glitches.

On the IRC, speachy suggested that it could have to do with the fact that the FLAC code in Rockbox is pretty old, and that converting it back “repacks” the data differently and regenerates the indices, and that specific sequences of bits don’t get handled correctly. So somehow, that one album I downloaded was converted/packed to FLAC in a weird or unorthodox way.

In the attached sound file, it happens throghout. An example is right at the 2:35 mark.