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Why upsampling would degrade sound quality ?, DAC job vs software job
extrabigmehdi
post Jun 16 2012, 03:38
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I was thinking that the DAC must be doing interpolation itself in order to reconstruct the final smooth signal.
So if we upsample with sox (i.e foo_sox) inside foobar , before the DAC interpret the data, I don't see why the upsampling would "deteriorate" the data, since anyway it would end up by being interpolated by the DAC. I don't understand the usual position I see, "don't upsample", it will just deteriorate data ...I was thinking that on the contrary, that upsampling before on sox, would just do a part of interpolation job before it's finalized by the DAC .
So beside chewing additional cpu cycles, I don't see why upsampling while playing music would be discouraged.
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saratoga
post Jun 16 2012, 03:42
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QUOTE (extrabigmehdi @ Jun 15 2012, 22:38) *
I was thinking that the DAC must be doing interpolation itself in order to reconstruct the final smooth signal.


Correct.

QUOTE (extrabigmehdi @ Jun 15 2012, 22:38) *
I don't understand the usual position I see, "don't upsample", it will just deteriorate data


Where do you see this? Properly implemented, upsampling will do nothing at all except waste space.

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extrabigmehdi
post Jun 16 2012, 04:19
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QUOTE (saratoga @ Jun 16 2012, 02:42) *
Where do you see this? Properly implemented, upsampling will do nothing at all except waste space.

Hum ok, I needed confirmation. Perhaps I'm a bit too much influenced by audiophiles.
But if I search a minimum here, someone talked of the quantization noise problem; I guess it's too small to be perceived.

This post has been edited by extrabigmehdi: Jun 16 2012, 04:19
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uart
post Jun 18 2012, 17:29
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QUOTE (extrabigmehdi @ Jun 15 2012, 20:19) *
QUOTE (saratoga @ Jun 16 2012, 02:42) *
Where do you see this? Properly implemented, upsampling will do nothing at all except waste space.

Hum ok, I needed confirmation. Perhaps I'm a bit too much influenced by audiophiles.


Well let me confirm that. I've done tests of re-sampling 44.1kHz to 48kHz, then back to 44.1 (so re-sampled twice) and then used audio analyzer software compare this with the original and check for any artifacts. Believe me that resulting artifacts were so low it would be completely pointless even trying to do a listening test. I was looking at graphs of added noise and harmonic/inter-modulation distortion and there was nothing above -130dB, so about 40dB below what I could even hope to try and hear. From the results I've seen I'd say that software resampling (done correctly) would be 100% inaudible (difference) to 100% of people. Yeah that's a pretty strong claim but I believe it.


This post has been edited by uart: Jun 18 2012, 17:55
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