View Full Version : Does compressing FLACS affect sound quality?

04-06-2015, 08:32 PM

Been at this for 6 months now and finding out the hard way that I'm running out of space due to having ripped a bunch of tunes to flac with 0% compression.

Iv'e got the original FLAC's from the CD's on my computer and synced to the cloud for backup, and have made a copy of each FLAC for library use, tagging, listening etc, and these copies are the ones I want to compress to save me some space.

I did an experiment and compressed one FLAC file into one FLAC file at DEFAULT 1 compression ratio, and it compressed it by 35%. I then ran both files through Foobar for a listening test, and I can honestly say that I can't hear much difference. The bass seems slightly heavier on the uncompressed tune, but wondering if my ears are playing tricks on me?

Is there really a difference? And if so, does anybody know the minimum compression ratio I need to keep the audio quality?

Thank you in advance!

PS. Also, If I compress said FLAC then copy it, can I bring that copy back to its original de-compressed glory at a later date?

Dat Ei
04-07-2015, 01:50 AM
Hey jacktheripper,

FLAC compression is lossless, just like the compression of zip, winrar, 7z etc. pp. So the compression level of FLAC controls only the file size, but not the audio quality. You can convert a FLAC back into a wave format without any loss of audio quality.

Dat Ei

04-07-2015, 07:36 AM
As Dat Ei points out, you are misunderstanding "compression" when it comes to LOSSLESS files, like FLAC. This "compression" is not at all related to creating lossy files like mp3 or m4a (where data is being thrown away). Compression affects SIZE of file and length of time it took to originally create the FLAC file. If you were in fact able to detect a difference in two FLAC files that had no errors, something would be terribly wrong somewhere. A FLAC file of any compression is decoded back to the original WAV file when played back. Thus no difference in sound quality.

04-07-2015, 07:39 AM
by the way, when you do your listening test in foobar2000 you should use the component that allows you to do a double blind ABX test in order to remove your expectation bias from the equation. You may need to install this component:


04-11-2015, 01:50 PM
Thanks guys, much appreciated!