# How To tell between a 'real' FLAC and a 'fake' FLAC?



## chinesekiwi

I know this question's been asked before and there was a program that someone mentioned that looked at the files via spectrograms and gave you readings such as indicating the peak kHz readings etc.... but couldn't find the thread.

 If anyone can give me a link to that program = great!


----------



## leeperry

True Audio Codec Software - Tau Analyzer - CD Authenticity Detector ?


----------



## AtomikPi

Sure.
Spectro - Freeware Audio File Analyzer

 By the way, you'll probably want to know that with LAME mp3's you'll get around 16 khz for 128 and around 19-20 for v0 and 320 (cd is around 22 khz) although of course for more information, Google is your friend.

 edit: also the above program is the best I've found - it reads flac natively, is super fast and lightweight, and is easy to use.


----------



## chinesekiwi

^
 That's the one.
 Anyway, I know about the encoding limitations 
	

	
	
		
		

		
		
	


	



 Also lossy, at least with mp3's, also cut outs information within the audible spectrum.


----------



## DeusEx

now that's why one of my FLAC folders sounds so bad...


----------



## Jany

Ill show you how i detect fake FLAC 
	

	
	
		
		

		
		
	


	




 Software: Spectro
 Homepage: http://spectro.enpts.com/

 FLAC vs MP3[320kbps]:




 MP3[128kbps <lol>]:




 After analyze fake flac you will see same specro like on source mp3.
 TIP: Not always you will have 22,1KHz but that don't means its fake.
 When i spectred full quality human sound solo, spectro is low xP
 On website are good news, author will add multiple scan option


----------



## khaos974

I woudn't be sure the difference is as clear as you make it, some recordings, for example CDs that were made from old recordings (the 60s ot the 70s), sometime simply don't contain high frequencies at all, or at a very low level. Similarly, I have some CDs which were recorded at a whooping -35dB average to allow for really high dynamics, and these contain very little HF info too. Do I need to talk about badly mixed pop music for which the samples used were already MP3s at the production stage?
   
  So looking for the missing frequencies is a bad method.


----------



## Pratt

Yea, I think there is more to it then just Freq. analyzing, especially because that's easy to get confused even for those who think they know what they are doing. It's a bit arbitrary and or misleading sometimes at least. I wish there was some simple definitive program one could use to scan lossless files to see if they truly are, without having to figure out freq. spectrums for each recording. I haven't found any yet; I've even used some on some cd's I knew were lossless because I ripped them myself and I got weird freq. spectrums and less than 100% probability for being lossless, sometimes even 70 to 80% probability for being lossy.
   
  I don't trust any program. The only way to truly know you have lossless is to buy and rip the cd yourself of course.


----------



## svyr

khaos974 said:


> I woudn't be sure the difference is as clear as you make it, some recordings, for example CDs that were made from old recordings (the 60s ot the 70s), sometime simply don't contain high frequencies at all, or at a very low level. Similarly, I have some CDs which were recorded at a whooping -35dB average to allow for really high dynamics, and these contain very little HF info too. Do I need to talk about badly mixed pop music for which the samples used were already MP3s at the production stage?
> 
> So looking for the missing frequencies is a bad method.




+1 transfers from old tapes/digital tapes for classical sometimes you get a FR from about 100hz to 8khz ... Sometimes whatever digital format they were stored in could well be a variation of Mpeg (l2, l3  ) so Cut-offs and inspecting the higher end spectrum for artifacts is a bit hit and miss.

Tau is for CDs, Aucdtect/Audiochecker (and a better AUCDTect GUI http://y-soft.org/English/products/auCDtect-Task-Manager/ ) are for encoded lossless files (basically it's a GUI on top of AUCDTect and WV,FLAC,APE, etc decoders. Decodes to wav, passes the wav to aucdtect and spits out the log.

Aucdtect is not very well regarded. It uses the analysis techniques described in http://en.true-audio.com/Tau_Analyzer_-_Aucdtect_Algorithm_Details
which appear to be sound, but people argue it doesn't spot non mp3 compression too well, especially at higher bitrates (ogg, aac, etc)

It also won't tell you whether someone decided to volume level the entire CD before encoding it  ...


Anyway, if anyone has ACM access and can pull http://portal.acm.org/citation.cfm?id=1597828 for us, I'd be interested to have a read (or anything on the similar theme that follow on from it or relates to it) . edit: ooh found it http://www.fileden.com/files/2009/2/14/2321055/My%20Documents/MP3%20Bit%20Rate%20Quality%20Detection%20through%20Frequency.pdf or something like http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4490000 / http://www.csie.nctu.edu.tw/~cmliu/Courses/Compression/Artifacts.pdf , since the other one is not cited...  (unfortunately there aren't automated tools for the later papers  ). UNfortunately, most papers seem to deal with low bitrate artifacts for things like VoIP, or watermarking or forensics...


----------



## xnor

pratt said:


> Yea, I think there is more to it then just Freq. analyzing [...]




Exactly. Unless you ripped the tracks on your own you simply cannot tell what happened to the files.

That's why there exist tools like AccurateRip for example.


----------



## svyr

xnor said:


> pratt said:
> 
> 
> > Yea, I think there is more to it then just Freq. analyzing [...]
> ...




ah, good point. If you have a tool that takes an AR log/cue file or just the plain flacs and verifies the CRCs that's probably a good indication. e.g. cuetools can do it, it think : http://forum.dbpoweramp.com/showthread.php?t=23610 or they mention a foobar plugin and that app: http://www.hydrogenaudio.org/forums/index.php?showtopic=87503




> CueTools can verify lossless rips of many tracks and albums at once - I believe that all such files would need to be under the same directory (or in a subdirectory) to accomplish this. You don't need to create a batch file and then run the batch file - this works form the user interface, and you don't need cue files. Results files are created for each album when you run this. The .accurip files are in fact text files and can be read by any Wordpad or the like.
> 
> I've had poor luck using the Accuraterip Manager plug-in with Foobar - CueTools is far superior. I don't think Cuetools can verify lossy files nor can it check across pressings, so it's not perfect, but I haven't found anyhting better to verify old rips. If there is a better tool I've love recommendations.




^ well, there we go...


----------



## Dobrescu George

i am using audacity.... it is hard to understand, it takes time and effort to read it's graphics, and it makes a little- to no sense... but it shows which is flac which is not flac.... because it shows if the information contained in the song is expanded or not, and it shows if the song has unaudible-but present parts...l.


----------



## Fatalethal

weird... i tried selecting all the songs i ripped using dbpoweramp but it says failed when attempting to load the song into the spectro


----------



## Dobrescu George

ok, fatalletal.... it is about how they were encoded, i have this problem too... encod a flac with flac encoder, for the name of what is right in this world....


----------



## aqua11alta

Quote: 





dobrescu george said:


> i am using audacity.... it is hard to understand, it takes time and effort to read it's graphics, and it makes a little- to no sense... but it shows which is flac which is not flac.... because it shows if the information contained in the song is expanded or not, and it shows if the song has unaudible-but present parts...l.


 


  Hi. can you tell me more about that? How do you tell which is 'fake'/'real' flac? I just downloaded Audacity and chose the function 'Analyze' --> 'Plot Spectrum', but I don't know how to translate the the spectrum 
   
  thanks


----------



## koolkat

Can you tell the difference between a lossless file and a lossy file in a ABX test o.o"


----------



## Fatalethal

depends on each individual i guess....


----------



## wnmnkh

In short, there isn't any reliable way to identify fake and real lossless data.
   
  You may want to search Hydrogenaudio forum for more information.


----------



## koolkat

Can you provide some links to good discussions? There are a gajillion topics in there,
  
  Quote: 





wnmnkh said:


> In short, there isn't any reliable way to identify fake and real lossless data.
> 
> You may want to search Hydrogenaudio forum for more information.


----------



## bereke70

only works for Windows. Any such check for IOS?


----------



## autoteleology

http://www.whatinterviewprep.com/prepare-for-the-interview/spectral-analysis/

 The only tried and true way to know.


----------



## pookeyhead

atomikpi said:


> Sure.
> Spectro - Freeware Audio File Analyzer
> 
> By the way, you'll probably want to know that with LAME mp3's you'll get around 16 khz for 128 and around 19-20 for v0 and 320 (cd is around 22 khz) although of course for more information, Google is your friend.
> ...


 

 Spectro doesn't play nice with files over 10 mins.  Seeing as it's common practice to have the entire album as one FLAC and then use a .cue file, Spectro is a bad idea.
  
 Try...
  
 http://losslessaudiochecker.com/


----------



## MaDD0G

bereke70 said:


> only works for Windows. Any such check for IOS?





Audacity is also working under IOS and can be downloaded from here:

http://audacity.sourceforge.net/download/


----------



## vermilions

Hi, sorry for digging out an old thread, but I have a question regarding these spectral diagrams. I'm not sure how to interpret these two MP3 files and would love some help.

 So the first one is a a 256 kbps MP3 file ripped a long time ago using iTunes.
 The second one is a 320 kbps MP3 file, converted from a FLAC version to MP3 via XLD.
  

  
  
  
 Is this normal? According to http://www.whatinterviewprep.com/prepare-for-the-interview/spectral-analysis/,


> _ MP3 256kbps (CBR) has a frequency cut-off at 20 kHz_ and _MP3 320kbps (CBR) has a frequency cut-off at 20.5 kHz._


 
  
 It looks to me my "256 kbps" file fits the 320 kbps description more. Is there something wrong with my XLD? Or is everything fine and I'm just confused? Thanks so much.


----------



## scorpeeon

Any word about lossless files above 44.1/16? For instance I have some tracks in 88.2/24, tried most of the apps mentioned here, but none of them seemed to be able to handle them.


----------



## RRod

scorpeeon said:


> Any word about lossless files above 44.1/16? For instance I have some tracks in 88.2/24, tried most of the apps mentioned here, but none of them seemed to be able to handle them.




Sox handles hi res.


----------



## gevorg

scorpeeon said:


> Any word about lossless files above 44.1/16? For instance I have some tracks in 88.2/24, tried most of the apps mentioned here, but none of them seemed to be able to handle them.




*Spek* is multiplatform and handles hi-res.


----------



## Armaegis

vermilions said:


> Hi, sorry for digging out an old thread, but I have a question regarding these spectral diagrams. I'm not sure how to interpret these two MP3 files and would love some help.
> 
> So the first one is a a 256 kbps MP3 file ripped a long time ago using iTunes.
> The second one is a 320 kbps MP3 file, converted from a FLAC version to MP3 via XLD.
> ...


 
  
 If that "old" file was from many years ago, the encoder used may also be a factor since back then different encoders could sound quite different from each other (and I don't think itunes was very friendly with mp3 back then either)


----------



## stephenward

Thanks for the valuable information


----------



## csusza2000

Hi Guys
  
 I can not reach the official Spectro site given in the links above. Does anyone know what happened to the site? I have downloaded it a few times in the last 2 years. But now the web page is not opening. I would really appreciate any info. 
  
 Thanks, bye.


----------



## arnyk

vermilions said:


> Hi, sorry for digging out an old thread, but I have a question regarding these spectral diagrams. I'm not sure how to interpret these two MP3 files and would love some help.
> 
> So the first one is a a 256 kbps MP3 file ripped a long time ago using iTunes.
> The second one is a 320 kbps MP3 file, converted from a FLAC version to MP3 via XLD.
> ...


 
  
  
 Yes, what you have in general looks normal.


----------



## HKO2006

The site went down I am afraid but I am still able to download via the mirror.
 http://wayback.archive.org/web/20141113151216/http://spectro.enpts.com/download.php
 In case the above went down too, here is a backup: https://drive.google.com/folderview?id=0B151yw6KLtfGfm9XRUVtN0tpbk9JS2ZiN21aQ0R1bDFVaS1pY293T01xOFhZQVJjNjYwcTQ&usp=sharing
  
 If both failed, google Spectro 1.0.93.
  
 The homepage
 http://wayback.archive.org/web/http://spectro.enpts.com/download.php


----------



## Antonis Vlachos

Hey man, 
  
 The last years i am using a free tool, the best in my opinion. Its for windows,mac and Linux and its called SPEK. http://spek.cc/
  
 You just drop the file there. I have tested it on 24/96khz and it worked fine. Give it a try and you'll love it.


----------



## Alexium

Spectro is great, but can't handle single-track lossless releases (image + .cue). Makes me wish to make a similar program, but with no such limitations and with batch mode support (e. g. "scan everything within the specified set of folders").


----------



## lawlbear

Wouldn't file size be a good starting indicator?


----------



## ExtremeGamerBR

AccurateRip is by far the best way to see if you have a REAL Flac.


----------



## The Walrus

I tried Spectro with some of the CD's I ripped using Media Go, and it shows a cut-off frequency of 20.5 KHz.
 What is more confusing is, one album I bought from Qobuz.com shows 16.5 KHz! (Although the graph shows spikes here and there all the way to 20 KHz. 

 The upper limit of human hearing is 20 KHz. Could it be that the flac encoder is cutting the frequency off there somehow?? So confusing.


----------



## ExtremeGamerBR

the walrus said:


> I tried Spectro with some of the CD's I ripped using Media Go, and it shows a cut-off frequency of 20.5 KHz.
> What is more confusing is, one album I bought from Qobuz.com shows 16.5 KHz! (Although the graph shows spikes here and there all the way to 20 KHz.
> 
> The upper limit of human hearing is 20 KHz. Could it be that the flac encoder is cutting the frequency off there somehow?? So confusing.


 
  
 Nop, FLAC does not cut anything. It is lossless, so nothing is lost. It compress the audio like a ZIP file, and the player descompress without loosing quality.
  
 Did you tried to check your files with AccurateRip? CueTools or Perfecttunes can do this. Only dBpowerAMP or EAC can upload rip results to the AccurateRip database. So, if you FLAC or whatever lossless format you are using gives at least V2 of confidence, it is a perfect rip. So, with this method you can check if the files are real AND if they was properly ripped.
  
 Sorry for my bad english.


----------



## The Walrus

extremegamerbr said:


> Nop, FLAC does not cut anything. It is lossless, so nothing is lost. It compress the audio like a ZIP file, and the player descompress without loosing quality.
> 
> Did you tried to check your files with AccurateRip? CueTools or Perfecttunes can do this. Only dBpowerAMP or EAC can upload rip results to the AccurateRip database. So, if you FLAC or whatever lossless format you are using gives at least V2 of confidence, it is a perfect rip. So, with this method you can check if the files are real AND if they was properly ripped.
> 
> Sorry for my bad english.


 
 Good idea. Will try it. Thanks


----------



## Bubblejuice

This is great! Thank you


----------



## Bubblejuice

What could I use if I have a huge FLAC file? I downloaded an album, but it turns out the whole album came in one FLAC file. It's 36 minutes long. Spectro says it's too large to process, but i'd really like to make sure it's solid.
  
 Thanks!


----------



## ExtremeGamerBR

bubblejuice said:


> What could I use if I have a huge FLAC file? I downloaded an album, but it turns out the whole album came in one FLAC file. It's 36 minutes long. Spectro says it's too large to process, but i'd really like to make sure it's solid.
> 
> Thanks!


 

 CUETools.
  
 Here is a good tutorial: https://losslessma.net/how-to-split-and-convert-single-file-flac-album-into-tracks/


----------



## zareliman

The spectral analysis is the most reliable way to find out about lossy compression but it's not perfect.

 Masters and audio processing can produce artifacts that can ultimately end up looking like a compressing algorithm was used at some point. Ultimately the auCDtect algorithm tries to do the same thing you are doing by naked eye. Algorithms work better or worse than humans depending on the problem.
  
 Quote:


vermilions said:


> Hi, sorry for digging out an old thread, but I have a question regarding these spectral diagrams. I'm not sure how to interpret these two MP3 files and would love some help.
> 
> So the first one is a a 256 kbps MP3 file ripped a long time ago using iTunes.
> The second one is a 320 kbps MP3 file, converted from a FLAC version to MP3 via XLD.
> ...


 
  
 That is largely depending on the encoding used. It looks like you're using CBR since it cut offs and sometimes the peaks go higher (when the data rate allows it). Try to change the scale of the frequency on your spectral analyzer to get further information on the upper frequency range.


----------



## Bubblejuice

extremegamerbr said:


> CUETools.
> 
> Here is a good tutorial: https://losslessma.net/how-to-split-and-convert-single-file-flac-album-into-tracks/


 
 Incredible tool, thank you!


----------



## Alexium

bubblejuice said:


> What could I use if I have a huge FLAC file? I downloaded an album, but it turns out the whole album came in one FLAC file. It's 36 minutes long. Spectro says it's too large to process, but i'd really like to make sure it's solid.
> 
> Thanks!


 

Spek is the best tool I know.


----------



## NoNameNPC

The Walrus said:


> The upper limit of human hearing is 20 KHz. Could it be that the flac encoder is cutting the frequency off there somehow?? So confusing.


No, I hear 21 KHz if turn volume on max.


----------



## Alexium

NoNameNPC said:


> No, I hear 21 KHz if turn volume on max.


I think there are humans who can hear 21 kHz, but there are very, very few of them. If I was in your position, I would suspect that what I'm hearing is a harmonic (a result of non-linear distortion that any tweeter exhibits because nothing is precisely perfect).


----------



## bigshot

NoNameNPC said:


> No, I hear 21 KHz if turn volume on max.



That is a great way to go deaf, champ.


----------



## gerelmx1986

I use spek to analyze


----------



## gregorio

NoNameNPC said:


> No, I hear 21 KHz if turn volume on max.



Really? There's certainly published science evidencing that high volume single tones above 20kHz are audible to some people but I don't know of any reliable evidence that indicates 21kHz is ever audible within complex/multiple tones (such as music recordings). And btw, you should be extremely careful about trying to find out, the sort of levels you'll need to stand even the remotest chance are probably at or beyond the point at which hearing damage can occur, even quite short durations. If you do actually detect some difference, almost certainly it will be IMD (inter-modulation distortion), as @Alexium stated. In fact, it's difficult to avoid IMD when reproducing high freqs at high levels.

G


----------

