You get a match against a verified yet errant submission from a download and it doesn't matter how many submissions from legitimate sources are made.
Also, when you think about it, the OP's question really doesn't make sense. The result of a FLAC compression is a lossless image of the source. In case you input a mp3-compressed audio, does that make the resulting FLAC "non-lossless" or "fake"? No, it doesn't. It makes it a perfect lossless version of the source material, regardless of what the source material is :-)))))On another note, if we are talking about identifing "fake FLAC" in files obtained by...ehm, questionable means, then AccurateRip comes in quite handy
Looking at a spectrogram of the audio is a good way to tell, but you need to look for more than just a low-pass filter.Here are three spectrograms made with SoX that show what to look for:First, the lossless original:http://farm6.static.flickr.com/5160/588503...19f4fd5_z_d.jpgNext, Lame MP3 at -V5:http://farm7.static.flickr.com/6023/588503...51ec1c8_z_d.jpgAnd lastly, Vorbis at -Q4:http://farm7.static.flickr.com/6011/588503...a8664a0_z_d.jpgThe main thing I look for is the "holes" in the audio that the lossy compressors psycoacoustic model determined to be inaudible due to auditory masking.
Quote from: XeR0 on 29 June, 2011, 04:39:02 PMThe only only to really know (to my knowledge) if a CD is authentic is to buy it from the publisher themselves.I guess Century Media doesn't qualify as a publisher?
The only only to really know (to my knowledge) if a CD is authentic is to buy it from the publisher themselves.
unless you've ripped the files yourself, how would you know the FLAC file you have is ACTUALLY lossless instead of an MP3 converted into FLAC?
I've used the TEST option in FLAC frontend and it doesn't give a result. I have used Audiotester and it does say the file failed because it's TRUNCATED.
There used to be a freeware DOS command line/console program that could examine a WAV and tell if it came from an MP3.
Quote from: greynol on 29 June, 2011, 04:46:29 PMQuote from: XeR0 on 29 June, 2011, 04:39:02 PMThe only only to really know (to my knowledge) if a CD is authentic is to buy it from the publisher themselves.I guess Century Media doesn't qualify as a publisher?What I meant was this: Let's say for instance I wanted to buy an album called "Tales of the Inexpressible". A trustworthy publisher would be "Twisted Records" instead of "World Music of New Age". A good amount of research would show that the composers of the album founded Twisted Records and sell their music there. Therefore, the only real way to make sure that you're getting an authentic CD, would be to buy it from Twisted Records and not from any other obscure publisher.
That's a good one.I was referring to some of the titles on the Century Media label available on Amazon.
...From what I've read, you can use Goldwave (a piece of software) to check the frequency graphs (much like post #35 above). Since lossy never (or almost never) reaches above 20k, it should be easily discernible. It's what they say in China, anyway, since there are so many "bad lossless" sources online there.
Can anyone give me a clue why i got so many differences. It doesn't look like the lossy paterns showed in a previous post so i guess both a re lossless, but it looks like they come from 2 different versions of the same song. I don't think this album was re-mastered.
...From what I've read, you can use Goldwave (a piece of software) to check the frequency graphs (much like post #35 above). Since lossy never (or almost never) reaches above 20k, it should be easily discernible.
You should really try the AuCDtect tools I told you about. They are much more advanced than any spectrogram guesswork by eye.
Unfortunately, this application only seems to works on physical CDs. I was trying to analyse FLAC files i bought as digital downloads.
EDIT : what makes you tell they were lossy? I tried looking for "holes" in the spectrum as on post #6 rather than just a pass filter and didn't see those. Is there something else to look for?
That's right, that Tau Analyzer frontend really should be updated to support analyzing lossless files. However, there's the command line tool and there's the foobar component to analyse files. Or, if you want to use the frontend, you could make a virtual image from your FLACs.
Of course it doesn't look like the spectrum from post #6 because that shows a time scale of ~4 seconds whereas your spectrum shows a time scale of ~260 seconds. You wouldn't look at a sattelite image of the country you live in and wonder why you can't see your house on it, wouldn't you?
I've re-analysed my files, selecting a 5 seconds portion, and here is the result :
sox <"Input file name"> -n trim <x> <y> spectrogram
Just decode them to wav or, like suggested, use some frontend that will do it for you.
By "False positives" do you mean files wrongly identified as lossy or wrongly identified as lossless (or both)?