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Topic: 160 vs 192? analysis (Read 4202 times) previous topic - next topic
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160 vs 192? analysis

trying to determine which file is better.

Is the 192 file slightly better or just a transcode?  I notice the blue goes a little higher on the 192 but cut off is the same.

I believe the source was unmastered

Re: 160 vs 192? analysis

Reply #1
Spectograms are not a good way to determine audio quality.
They are only meaningful when there are obvious problems on the audible range.

There's no way to know what is what, and yes, one possibility (but not the only one) could be that the 192kbps is a transcode.

Re: 160 vs 192? analysis

Reply #2
what are the thin blue lines in the 192 photos above 16?

Re: 160 vs 192? analysis

Reply #3
The blue lines at the top of the spectrum could be the result of someone using an equalizer to attempt to remove frequency content. It looks quite similar to the other encoding.

As for the original question, spectrograms are not reliable in terms of making real comparison of quality, especially when the FFT filters used to make spectrograms can never be perfect for every use case, and always "smear" the time or frequency domains in the image, and sometimes our hearing can't tell the difference even if you can see it in a graph and vice versa. As JAZ said, spectrograms are only meaningful when there are obvious problems in the audible range. The only way to know which is better is to ABX with the original.

Re: 160 vs 192? analysis

Reply #4
I actually had to deal with this problem not too long ago, where I wasn't sure if another MP3 was a re-encoding or an entirely new file. My way to approach it was with a spectrogram, but not Spek; I used a tool called Sonic Visualizer, but you can use whatever program you desire as long as you can zoom in very close to the audio. You might need to adjust the FFT size and overlap to see clearly enough.

In the original (256kbps CBR discrete stereo), there is just a little more audio data/artifacting in the high frequencies. The re-encode (190kbps VBR joint stereo) is almost identical, but it lacks just a bit of these artifacts. If you switch back and forth between the two images, you can see that pretty much everything is the same -- minus the high frequency artifacts.

It might not work exactly for your case as the file was re-encoded up in bitrate, thus an obligatory YMMV, but I've found that even one re-encode is enough to remove some of the very, very fine details.

Re: 160 vs 192? analysis

Reply #5
This is an old thread but we do not use graphs & measurements to judge sound quality.   See TOS #8

You can have a "pretty" graph with terrible sound or you can have a graph or measurement showing a flaw that you can't hear.

You do (usually) loose high-frequencies with MP3, but if you hear a defect/artifact with a good quality MP3 the loss of highs is NOT what you hear. 

Lossy compression throws-away data (to make a smaller file) and it tries to throw-away sounds you can't hear without regard to what you can "see".   In normal music (or other program material) the highest frequencies are masked (drowned-out) by slightly-lower high-frequencies (and the highest frequencies tend to be "weak") so although you might be able to hear up to 20KHz with loud pure-tones in a hearing test, you can't (usually) hear those frequencies in music,

If you hear a defect, a measurement or spectrogram might help to explain what you're hearing but lossy compression artifacts (the ones that damage the sound) aren't usually easily measurable. 

Re: 160 vs 192? analysis

Reply #6
TOS 8 is too narrow and needs clarified. For example: in terms of a loudspeaker's frequency response a graph is very useful in determining an aspect of sound quality, as would a graph of distortion. That's why we provide them with most audio components.

What TOS 8 really means is: don't flood the forum with FFTs of MP3 files

Re: 160 vs 192? analysis

Reply #7
TOS 8 is formulated in a way that, if read literally, forbids me from saying "1990 would be surprised at how good quality you can get out of 96 kbit/s bitrate".

Half of the dumbness could have been fixed by e.g. "a statement concerning differences in subjective sound quality".