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Topic: True FLAC vs. Fake FLAC (Read 58226 times) previous topic - next topic

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True FLAC vs. Fake FLAC
Reply #75
use and verify by spectrum. just consider date of the record
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  • incifinci
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True FLAC vs. Fake FLAC
Reply #76
I downloaded a fake FLAC from a blog site, with exact cut-off on spectrogram at 16 kHz. I tell them about, and they gave me a new one, with a frequency range up to 22 kHz - but the spectrogram is very strange, in my opinion, and has a big peak exactly at 16 kHz, too. I would like to know, is there a way to create fake FLAC with so exotic spectrogram, or is the new one is true FLAC? My earthes (by the test) are good (till 16 kHz), and I could not hear a quality difference between two files, using good enough quality JVC headphones.

2 FLACs, 2 Spek images + Audacity frequency analysis image are here. Thank you in advance for help.

(This like peak seems on the 60% of songs of the full album. Disney Aladdin soundtrack, hungarian, 1992.)
  • Last Edit: 15 December, 2015, 07:06:56 AM by incifinci

  • xnor
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True FLAC vs. Fake FLAC
Reply #77
From a quick analysis I conclude it's just noise added on top. Maybe their source material just isn't better..
  • Last Edit: 15 December, 2015, 07:48:10 AM by xnor
"I hear it when I see it."

  • mjb2006
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True FLAC vs. Fake FLAC
Reply #78
The first one is almost certainly transcoded from lossy, IMHO. The 13 to 16 kHz range is very selective, 16 kHz and up is just occasional noise. The spectrogram in Audition has the look of a piano roll / low-res brick-out game.

The second one has instrumental harmonics going well above 16 kHz. Everything is smooth, no blockiness. The noise at the high end looks like shaped dither, so probably it was converted down from a higher-res source. Not a transcode, in my assessment.

Here I have zoomed in on a 4.7-second section from about 10.5 kHz to 16.5 kHz and am toggling back and forth between the lossy and lossless. Levels are not matched, so ignore the difference in brightness. I am not showing the harmonics or dither noise above 16 kHz; it's just showing the blockiness. Click on the image and view it at full res if you can.

Anyway, if you can't hear a difference, the lossy encoder did a good job deciding what to throw away, and the quality levels are by definition the same. But of course you don't want to be paying for one thing (*cough*) and getting another, even if you can't hear the difference.
  • Last Edit: 15 December, 2015, 08:38:19 AM by mjb2006

  • incifinci
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True FLAC vs. Fake FLAC
Reply #79
xnor, mjb2006, thank both of you for help. Especially was helpful for me the explanation of the high end noise's origin (dither).

About the peak at 16 kHz: this was not the first time, when I met this like peak. mjb2006, what do you think, is its cause the downconverting from a higher-res source, too? (As I read in wikipedia about dithering, if I understood it well.) Or is it simply because of the quantization (signal processing)?
  • Last Edit: 15 December, 2015, 01:02:34 PM by incifinci

  • greynol
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True FLAC vs. Fake FLAC
Reply #80
Your eyes cannot hear.

  • incifinci
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True FLAC vs. Fake FLAC
Reply #81

Thank you for a good link!

It's unfortunate, that the cause is not find, but anyway, it's good to know, that it's not because of transcoding or ripping.