spotting fake FLACs?

Discussion in 'Digital Audio' started by photogpab, Sep 8, 2012.

  1. macrumors 6502

    photogpab

    Joined:
    Jun 21, 2010
    #1
    any program I can use to spot fake flac or lossless files?

    a few people mentioned audio checker but i dont think its available on mac.
     
  2. macrumors 6502a

    Blackberryroid

    Joined:
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    #2
    I do not listen to FLACs, I listen to ALACs, which is lossless but it's for iTunes, iPhone and iPod so I wouldn't have to worry about converting it to low quality MP3.

    The best way to spot fake FLACs is to check their bit-rate. If it's below 500, you got the fake one. Typically, FLACs are 1000+ kb/s, but some are also 600 KB/s.
     
  3. macrumors 6502a

    bwhli

    Joined:
    Jan 9, 2012
    Location:
    Boston, MA
    #3
    You can run it through a spectrum analyzer. If it has a brickwall on the high frequencies, it's probably not true lossless. Lots of lossy compression codecs take out the high frequencies.
     
  4. macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #4
    The for-sure method isto compare the decompressed FLAC to the WAV file you got from the CD. Subtract the two files in an audio editor.

    Lacking the CD, the best way to check is to convert to WAV and then look at the file with something like Adobe Audition or some other analisys tool. An FFT plot would tell you quite a lot.

    A quick way is to simply look at the file size compared to other FLAC files of the same music genre and length. A"fake" will be shorter. Seeing the short file then you check it using above methods

    But on the other hand if your ears can't tell by just listening why would you care? I assume if you don't know the history of the file you got it as a free download, why complain about the quality of stolen music?
     
  5. macrumors 603

    blueroom

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    Feb 15, 2009
    Location:
    Toronto, Canada
    #5
    Ahh thanks, I couldn't figure out how you could have a fake FLAC.
     
  6. macrumors 6502

    Joined:
    Sep 13, 2010
    #6
    Lossless formats aren't typically used directly for audio reproduction you know...

    The idea is to preserve a bit-perfect copy of the original so that when you encode it, you'll be preserving as much of the original signal as possible.
     
  7. macrumors newbie

    Joined:
    May 20, 2010
    #7
    This method isn't rigorous at all, but sometimes you can 'spot' compression in the audio spectrum, with AAC I believe it looked like lots of little blocks or squares punched out where you would expect it to be continuous, usually in the very high frequencies.
     
  8. macrumors Core

    alphaod

    Joined:
    Feb 9, 2008
    Location:
    上海 (Shanghai)
    #8
    I don't understand the fake FLAC business. If you're ripping your own music, how the world would it be fake unless you used the wrong source.

    If you're buying music online (like HDTracks), I've never had issues with their music.
     
  9. macrumors 6502a

    bwhli

    Joined:
    Jan 9, 2012
    Location:
    Boston, MA
    #9
    Some people download FLACs from "free" sources.
     
  10. macrumors 6502a

    shigzeo

    Joined:
    Dec 14, 2005
    Location:
    Japan
    #10
    This is probably the best answer in this thread. FLAC can be re-encoded to any bitrate, so looking at that alone will leave you with more questions than anything. Running a spectrum analyser will give you a visual comparison of the data inside.

    We all know that listening to the files (especially if one is in doubt) will not do the trick: ears are too easily fooled. Half a decibel louder and suddenly: it sounds better.
     
  11. macrumors newbie

    Joined:
    Feb 25, 2013
    #11
    Unfortunately this isn't a fail safe. I did a few tests as I have a few ALACs that I did not rip myself (cough), and I wanted to verify their authenticity. I ran a few suspect and a few confirmed ALAC files through a spectrum analyzer, as well as a few MP3s. All of the MP3 files had the visual cut-off you are referring to. Some of the ALAC files did as well. Some visually did not. I thought, "Great the cut off files are fake!", until I took some CDs that I had and created ALAC files straight from them myself. Lo and behold, they had the same frequency cut-offs that the MP3 files did. Apparently whether or not the files have those frequencies can be caused just as much from the source as the encoding method.

    Bummer. Too much compression in the CD mastering process maybe?

    I guess the only way to really tell is to directly compare the source cd with the ripped file.

    Caveat emptor: I am not an audio pro, but I did stay at a Holiday Inn Express last night.
     
  12. macrumors member

    Joined:
    Aug 3, 2012
    #12
    i would argue that if you're needing a program to tell you before you notice it probably doesn't matter.

    it should stick out as sounding like an mp3, if it doesn't, or you're not hearing a difference without a program telling you it's an mp3 conversion then, why care?
     
  13. macrumors newbie

    Joined:
    Feb 25, 2013
    #13


    I don't disagree with your point. Most MP3s do stand out. I've got a good enough setup that I can easily tell, especially when comparing side by side. Unfortunately I don't know if I can tell 100% of the time without a comparison. I just want to know, you know?
     
  14. macrumors member

    Joined:
    Aug 3, 2012
    #14
    Fair enough, I would see if you can check with your source of the files then.
     
  15. macrumors 601

    Mr. Retrofire

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    #15
    I use my ears, good headphones and the correct equalizer settings.

    ----------

    Really?

    ;-)
     
  16. macrumors 6502a

    shigzeo

    Joined:
    Dec 14, 2005
    Location:
    Japan
    #16
    No a spectrum analyser will not tell you what file is uncompressed and of higher intrinsic quality (without size compression or inflation) but will show how much dynamic range is lost due to dynamic compression to emphasise loudness.

    ----------

    Again, it isn't so easy. It has not been proven one way or another that users CAN hear a difference unless the files are very very poorly recorded. New algorithms are good enough even at 128 that I doubt most 'golden ears' could tell a difference if the volumes of both songs were perfectly matched.

    The ear is very very easily tricked.

    And doing the test yourself, unless it is a blind ABX, is meaningless. Even then, there are too many questions raised. I'd say, if in a blind test with 100% matching volumes, you fail to suss which is which in more than 1/3 of the phases, it doesn't matter. Such tests require specific pieces of software, not a random play in iTunes and absolutely must be volume matched. I suggest having someone with you to keep you straight.

    Often, 'good' systems are even more prone to lies. Why? Good, expensive systems introduce their own flavour - that is, unless you invest in a system that aims for bit accuracy. Those systems don't usually cost that much. Benchmark is much cheaper than Antelope and Antelope DACs are still cheap in the grand scheme of things.

    Hell, an ODAC should do it and it is cheap. Feed it to a truthful system (Good monitoring headphones like Beyer DT770 may be better in this case, than speakers).

    I meet 'golden ears' all the time. And they are often the easiest to fool as they want to believe anything. It's the normal folk who tend to spot truth faster as they are in essence, doubters.
     
  17. macrumors 6502

    Joined:
    Sep 13, 2010
    #17
    From my post the other day:

    *****
    http://forums.macrumors.com/showthread.php?p=16873587#post16873587

    Besides using foobar ABX or equivalent, the two files to be compared must be derived from the same mastering, and preferably the exact same source (one from the other obviously counts); otherwise, you may be testing for differences in mastering, not encoding, and differences in mastering can be genuinely profound and trivial for anyone to ABX.

    There is an infinite amount of nonsense in discussions about these things. Here is a fairly detailed slideshow of a scholarly presentation that used high-end equipment under ideal conditions:

    http://www.music.mcgill.ca/~hockman/documents/Pras_presentation2009.pdf

    Its conclusion were:

    • Trained listeners can hear differences between CD quality and mp3 compression (96-192 kb/s) and prefer CD quality.
    • Trained listeners can not discriminate between CD quality and mp3 compression (256-320 kb/s) while expert listeners could.
    • Ability to discriminate depends on listeners’ expertise and musical genre.
    • Artifacts can be verbalized and do not depend on musical genre.

    I think AAC is a lot better than MP3 at low bitrates, judging by my threshold for hearing artifacts in various "killer samples", which disappear for me at AAC 128 Kbps but persist in LAME 3.98 MP3 up to 192 Kbps and a little beyond. I've also found transcoding high bitrate MP3s to AAC to be much more transparent than going MP3->MP3, which introduces obvious artifacts after one generation. If you want to read a lot of subjective crazy talk including things like cable directionality, try the stevehoffman.tv forums. For people who value blind listening tests, try hydrogenaudio.org.
    *****

    Yep. And when I said I could hear artifacts in some killer samples at 192 Kbps MP3, that says nothing about most music, which I find transparent at that level. While most of my library is lossless, I always have iTunes transcode to 128 Kbps AAC when syncing to my 64 GB Touch. There are apps for ABXing directly on the Touch, and I've found there is no reason to encode at a higher rate for how I use my Touch. There might be brief, infrequent moments of non-transparency that I might notice under ideal conditions and with higher quality equipment that I normally use, but it would be stupid to sacrifice a ton of storage out of fear of that.
     
  18. macrumors 6502

    Joined:
    Sep 13, 2010
    #18
    If you have a whole album in lossless format, many can be verified against AccurateRip with CueTools or foobar2000 on the PC. A minority (10%?) require the .cue file in order to verify.
     
  19. macrumors newbie

    Joined:
    Feb 25, 2013
    #19
    I don't think that anyone here is claiming to have "golden ears", but I certainly do think that there is a marked difference between (some?) mp3s and lossless files. I still have songs from back when "torrenting" was simply browsing your college network for songs to play with winamp. When replacing these songs with lossless rips, there's an audible difference in the quality. I don't think any mp3 I had was over 192kbps; most under 160.

    Of course I am probably comparing the worst-case scenario to the best-case, but never-the-less I stand by the idea that there's an audible difference to be heard.

    I also buy direct from an artist when there's a high-quality (32bit wav!) download available. On top of buying direct, I know I'm getting the best possible quality in the off chance that sometime, maybe, I'll have the system and ear to reproduce the files. Plus, as these files will be backups, I'll have a perfect source to rip smaller versions from when needed.
     
  20. macrumors 65816

    Joined:
    Jul 6, 2007
    #20
    Didn't realize FLAC had been taken over by pirates. That's usually how Grateful Dead shows are encoded and it's legal to download their music. Other bands are cool with live shows being traded as well.
     
  21. macrumors 603

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #21
    FLAC is open source and can be used (taken over) by the pope or Kim Jong-il.:eek:
     
  22. macrumors 6502a

    shigzeo

    Joined:
    Dec 14, 2005
    Location:
    Japan
    #22
    I don't check this thread or MR forums often enough as I live in another forum called headfi. Need to start a more permanent spot here.

    Files from back then will be encoded from those days. The poster above who responded at length to me is right: there are profound differences between encoding samples. Today's AAC files at low bit rates such as 128 are better than yesterday's MP3 files at 320. But today's MP3 is very very good. I heard samples that were coded at 1997 MP3 encoding that sounded awful.

    As mentioned above: files from the same CD could be ripped at same volumes, diff. bitrates, different engines (volume must be lossless though). A different mastering year or equipment can make a heap of difference; simply putting any old FLAC vs any old AAC isn't going to be fair - for one or the other as there are so many variables.

    Everything the same, I've not met a single person that could reliably tell the difference past 192kbps despite hugging their STAX and associated gear to their hearts. I admit that I cannot reliably tell between all-variables-equal encodings using the latest/best software.
     

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