Muggy wrote: > The upsampling involves simply adding zeros after each data point to > pad the data out - 146 zeros after every data point. This leaves the > frequency content unmolested over the bandwidth of the original > signal.
I don't think this is correct. I'm not even sure where you would "add zeros" to anything. There are two approaches to upsampling. I'll take an easy example. Assume you have a 44.1khz signal and want to to be 88.2kHz. Also assume that the PCM data looks like 0, 2, 4, 6, 7 for the first samples. To upsample it, you first double the number of data points. 0, 0, 2, 2, 4, 4, 6, 6, 7, 7 Then you can decide if you want to leave the data 'as is' with duplication, or if you want to do some interpolation. You could, for example, do simple linear interpolation, giving 0, 1, 2, 3, 4, 5, 6, 7, 7, 7, Or you could do a higher order quadratic or other functional smoothing. Then to reduce the sample rate, you just throw away data. So to go from this 88.2 to 44.1, you just pick every other sample. this would give you, tada, 0, 2, 4, 6, 7 Now, if you want to widen the data, say from 16 bits to 24, the crude approach is to just add 8 bits of zeros to each value. But adding zeros doesn't address the sample rate. -- Pat http://www.pfarrell.com/music/slimserver/slimsoftware.html _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
