In Reply to: RE: Converting DSD to PCM posted by dtc on August 5, 2015 at 18:00:56:
The problem is that if you don't do integer downsampling then you can't do a simple decimation. Instead, you have to interpolate points in between where you put the +- 1's. This can be done, but you have to have a separate bank of filter coefficients for each intermediate point of interpolation. This may or may not be a problem in practice, e.g. it will depend on cache sizes. If you don't use really accurate arithmetic and really accurate filter coefficients, then there will be time varying errors caused by the interpolation process and these will be at the beat frequency, potentially in or near the audible range. I suspect that if done properly (with sufficient horsepower) then the more complex filtering for 192 could well sound as good as 176.4, but I can't see what the point of doing this would be. Going the other way, I have no problem using HQPlayer to upsample 96 or 192 to DSD128. This sounds better then upsampling 96 to 192 or playing 192 directly on my Mytek DAC.
If you want to learn how sample rate converters work then there are text books on digital signal processing that explain this, but you will need college level calculus to understand them (and a lot of time and patience).
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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Follow Ups
- RE: Converting DSD to PCM - Tony Lauck 08/5/1518:27:34 08/5/15 (2)
- RE: Converting DSD to PCM - dtc 18:56:08 08/5/15 (1)
- RE: Converting DSD to PCM - Tony Lauck 19:45:20 08/5/15 (0)