Comment on how Quantization is covered in Textbooks |
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Comment on how Quantization is covered in Textbooks |
Mar 12 2012, 17:50
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#1
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Group: Members Posts: 63 Joined: 21-January 09 From: UK Member No.: 65825 |
The way digital audio quantization is covered in textbooks is flawed. A waveform derived from an undithered digital recording at 16 bits is treated as if were the same as an analogue signal with signal to noise ratio of 96 dB. This is actually wrong and leads to false conclusions. Adding 1 millivolt of noise when making an analogue recording would not make all details below 1 millivolt in height inaudable, using a quantization level of 1 millivolt when making an undithered digital recording would.
Put simply the signal to noise ratio of 16 bit audio is not 96dB in the conventional meaning of noise unless it is dithered. As for false conlusions well for example using more than 16 bits should not be dismissed by using a signal to noise ratio argument based simply on the number of bits. This post has been edited by KMD: Mar 12 2012, 17:57 |
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Mar 12 2012, 18:14
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#2
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Group: Developer Posts: 618 Joined: 6-December 08 From: Erlangen Germany Member No.: 64012 |
... Adding 1 millivolt of noise when making an analogue recording would not make all details below 1 millivolt in height inaudable, using a quantization level of 1 millivolt when making an undithered digital recording would. Which is why you should always dither. Most literature assumes dithering, I guess. And to be precise: by quantization level you mean "quantization threshold", right? i.e. quantization level = (quantization step-size) / 2? Chris -------------------- If I don't reply to your reply, it means I agree with you.
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Mar 12 2012, 18:16
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#3
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Group: Members Posts: 4137 Joined: 2-September 02 Member No.: 3264 |
The way digital audio quantization is covered in textbooks is flawed. A waveform derived from an undithered digital recording at 16 bits is treated as if were the same as an analogue signal with signal to noise ratio of 96 dB. This is actually wrong and leads to false conclusions. Every textbook derivation I've seen has made clear that this is only true under the assumption that the quantization error is uncorrelated with the signal (e.g. that the signal is dithered). Which text are you using? |
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Lo-Fi Version | Time is now: 26th May 2013 - 00:46 |