On Fri, 1 Oct 1999, Robin Harbron wrote: > Is the best way to convert a 16 or 8 bit sample to 4-bit (to play > on the SID) just to take the most significant (nibble?) nybble? It depends. If the conversion has to be done on-the-fly, in one pass, then it probably is. Otherwise, you could make a histogram of the sample* and make the quantification to 16 values based on the histogram. A cheap approximation would be to determine the minimum and maximum sample and use a formula like quant = 16 * (value - min) / (max - min) for the quantification. For instance, when quantifying 8-bit samples having min=50 and max=170 (which is equivalent to min=50 and max=120) the simple quantification of taking the most significant bits would waste one bit of accuracy. Probably someone will follow up to this and tell what kind of digital signal processing algorithms you could apply, and whether the histogram idea is feasible at all. Doesn't dithering imply increasing the sampling frequency? Marko * "sample" actually means just one sample (e.g. one 8-bit value), but the word is often used for referring to a sequence of samples. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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