Originally Posted by username10000
So I have been reading on the topic to see if the flac files I have are really lossless.
The consensus seems to be you don't know for sure unless you ripped it yourself.
But for the listening purposes, isn't the test linked below enough to know nothing has been attenuated too far?http://www.head-fi.org/t/442888/how-to-tell-between-a-real-flac-and-a-fake-flac#post_6979725
Or is virtually lossless not enough? I don't think people (at least me) can tell the difference between whatever the link has in the pic and true lossless file when they're listening.
It appears that you are confusing "lossless codecs" with "perfect copies of a CD original".
FLAC is an acronym that stands for "Free Lossless Audio Code." It is by design a lossless audio format. What that means is that given a PCM stream of audio (whether it comes from a CD, wav files, decoded mp3 or aac or ogg, etc.) FLAC will encode that PCM stream exactly. Therefore, once you play back your flac file, it will be 100% identical to whatever source it was made from.
So, to answer your thread title: yes, FLAC is 100% completely perfectly lossless.
Now, to address the question you meant to ask "are all flac files perfect copies of a CD?" Well, in general, no. FLAC files are perfect copies of whatever source was used. If that source was 128 kbps Frauenhoffer mp3 encoded in 1995, that you can bet that your flac file is a perfect reconstruction of a terribly (lossy) compressed track.
If you made the flac files yourself by ripping a CD or by encoding your own original music composition, then you can rest assured that you have a perfect copy of that CD or that production. If you download music from HDtracks, you're probably getting at least CD quality (16/44.1) but no promises about anything more. If you pirate music off of file sharing networks, there's no guarantee that the flac files you are downloaded are genuine CD rips.