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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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pdq
post Aug 31 2012, 14:52
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QUOTE (benski @ Aug 28 2012, 13:37) *
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?

So, after all of the back and forth of how to measure the SNR of an mp3, has this question been answered?
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benski
post Aug 31 2012, 21:08
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QUOTE (pdq @ Aug 31 2012, 09:52) *
QUOTE (benski @ Aug 28 2012, 13:37) *
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?

So, after all of the back and forth of how to measure the SNR of an mp3, has this question been answered?


It was a rhetorical question. Of course it's not enough to capture the output of MP3. LPCM's quantization noise is spread out evenly across the entire spectrum (noise-shape dither can do some juggling, but not much), but of course MP3 has low distortion levels "where it counts".

The main point of bringing up the subject, and I hope everyone gets the point, is that simply taking the SNR or THD+N and dividing by 6.02dB and saying "use this many bits" is not an accurate model.
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