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SNR of MP3, Split from Topic ID #96702
benski
post Aug 28 2012, 18:37
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QUOTE (jensend @ Aug 27 2012, 11:45) *
The LP noise floor is rather high- maybe -70dB under very good conditions. 12-bit sampling (RMS noise floor of -72dB) would be sufficient for LP use as long as your levels are right (peak signal above -6dB). (12-bit sampling was used for DV but hasn't seen any other widespread use).


The SNR of an MP3 is around 25-30dB. Does this mean that I only need to decode them to 6-bit PCM to capture all the details?

I am curious if anyone has ever done a detailed analysis of an LP's SNR in different frequency bands.

This post has been edited by benski: Aug 28 2012, 19:07
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pdq
post Aug 28 2012, 20:20
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QUOTE (benski @ Aug 28 2012, 13:37) *
The SNR of an MP3 is around 25-30dB.

I don't know why you say that. The dynamic range of mp3 is obviously much greater than 30 dB.

I would be more inclined to describe mp3's deviation from the original as distortion rather than noise, because it is quite capable of rendering very quiet passages with very little added noise.
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Arnold B. Kruege...
post Aug 29 2012, 12:41
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QUOTE (benski @ Aug 28 2012, 13:37) *
QUOTE (jensend @ Aug 27 2012, 11:45) *
The LP noise floor is rather high- maybe -70dB under very good conditions. 12-bit sampling (RMS noise floor of -72dB) would be sufficient for LP use as long as your levels are right (peak signal above -6dB). (12-bit sampling was used for DV but hasn't seen any other widespread use).


The SNR of an MP3 is around 25-30dB.



In which alternative universe? At what ludicrously low bit rate?

SNR is a measurable quantity. I've measured it in high-bit rate MP3s. The exact number escapes me but I seem to recall some number north of 80 dB. It was so high that I questioned the use of bandwidth to maintain it.
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2Bdecided
post Aug 29 2012, 17:45
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QUOTE (Arnold B. Krueger @ Aug 29 2012, 12:41) *
QUOTE (benski @ Aug 28 2012, 13:37) *
The SNR of an MP3 is around 25-30dB.


In which alternative universe? At what ludicrously low bit rate?

SNR is a measurable quantity. I've measured it in high-bit rate MP3s. The exact number escapes me but I seem to recall some number north of 80 dB. It was so high that I questioned the use of bandwidth to maintain it.
The dynamic range of mp3 is insane. The format itself has several hundred dB of dynamic range, and some 24-bit decoders give the expected 140dB.

But the "THD+N" (if you want to call it that) of mp3 with a complex test signal is often about 25dB below the test signal.

Cheers,
David.
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