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I downloaded some audio files with flac extension. I only had cheap earphones at that time and I couldn't really figure out whether it is real flac or just fake. Later when I played it through my friend's hifi system, It was totally unbearable. I guess, it was converted to flac from a lossy format. I don't have a clue on why someone would do this.

Is there a way to identify files that are converted from lossy to lossless formats without hearing it through a hifi system?

I checked the details of the file in windows explorer but no luck.

Thanks for helping.

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"without hearing it through a hifi system" hifi systems are typically not really a good at monitoring anyway. Get a pair of decent (studio) headphones, these will make such artifacts far more obvious than any consumer-grade system! — But as for detecting such artifacts without any hearing at all: what exactly do you have, one file that is either lossless or lossy (and you want to know), two files one of which is known to be lossless (and you want to know whether the other is lossy), or two different files (and you want to know which one is lossless and which is lossy)? –  leftaroundabout Aug 25 '12 at 21:51
    
I have one file and I would like to know if it is converted from a previously lossy format (mp3) to lossless (flac). Thanks for suggesting studio headphones. I will check that out. –  Ramnath Aug 26 '12 at 4:15
    
I'm pretty sure the answer is "yes, easily" because of how the various codecs work. But this site probably isn't the right people to ask—you need to ask the people who actually design and implement the codecs... –  derobert Aug 29 '12 at 21:07
    
In fact, Googling eventually found a program. Its from 2004, so is no doubt nowhere near state-of-the-art: hydrogenaudio.org/forums/index.php?showtopic=27910 –  derobert Aug 29 '12 at 21:17
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Flac is just flac - it will accurately encode whatever is fed into it. You are right though, that if you feed in a poor quality audio file it will remain a poor quality file.

The only likely way to do this would be through spectrum analysis:

Analysis of the frequencies in the file may indicate compression or sampling artifacts, but automatically scanning for this may be misleading, as some audio might deliberately have the same frequencies (there is a lot of strange music out there!)

Your best bet is to listen to a fragment of each one - it will be obvious pretty rapidly, and you can get through them quite quickly that way.

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Thanks for confirming. I will go with a good pair of headphones then. –  Ramnath Aug 26 '12 at 4:16
    
You may also be hearing compression artifacts that are in the original recording. Some of the more recent recordings have been so heavily compressed during the mastering phase you actually get some distortion when playing them back. –  Friend Of George Aug 28 '12 at 11:24
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Load the file into an audio editor with a spectrum view. There is also Informer, a real-time spectrum analyzer intended for exactly this use case.

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