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How to get SNR of MP3 file?
melangbong
post Sep 2 2013, 06:55
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Hello every body.

Sorry if this question is always bothering you all, but i am in a lost here.

Do anyone know what windows apps to get SNR value of mp3 files? Or how to calculate using those apps??

Thanks in advance.
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pdq
post Sep 3 2013, 00:58
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The usual method of measuring SNR would be to measure the amplitude of the largest possible signal, and the amplitude of noise when the signal has zero amplitude, and then take their ratio. MP3 is capable of a dynamic range of more than 200 dB, so I doubt that this measurement of SNR is what you had in mind.

There is also the ratio of signal to "noise plus distortion", which is probably closer to what you had in mind. The problem here is that a perceptual encoder is allowed to introduce all kinds of "distortion", as long as the result is perceptually close to the original.Many people make the mistake of subtracting the original from the decoded result and thinking that is a measure of the noise added by the encoder. In fact, such a measurement is pretty much useless.

So the bottom line is, I don't think that SNR is a useful concept to apply to perceptual encoding.
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greynol
post Sep 3 2013, 01:58
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Like SNR, SINAD won't work for pretty much the same reason: single pure tones are trivial to encode and reproduce.

Subtracting an encoded complex signal (music) from the original, taking its RMS and dividing it by the RMS of the original is what I would do in an attempt to measure it. If the result were in the vicinity of 35 dB I would call it a success. This is the number that comes from forum members that I trust, IIRC.

If you haven't already, search the site. SNR of MP3 has been discussed before and on more than one occasion.



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