Re: DSD to PCM Question

seanbroderick20003@xxxxxxxxx <seanbroderick20003@xxxxxxxxx> wrote:
Can someone describe how a piece of software would take a 1 bit
stream, and convert it to whatever bit depth PCM? I'm familiar with
PCM sample rate conversion when the bit depths are identical. Then
it's just upsample to least common multiple, filter, and downsample
(assuming your going down by other than simple whole ratios). What I
don't understand is how 1 bit information is piled up to make PCM
words.

DSD has a single bit that tells you if the signal is rising or falling.
It records at a very high sample rate.

insample=1 ; we're starting at the beginning of the data set
outsample=1
datasum =0 ; this is the current value of the signal.

while there is data

for i = i to dsdrate/pcmrate ; go through a block of data representing
if in[i+insample]=1 then ; one sample of the PCM output and look
datasum=datasum+1 ; through the DSD data to see what the
else ; final output level is.
datasum=datasum -1
end for

insample=insample+i ; advance to the next block
out[outsample=datasum ; store the data sum
outsample=outsample+1 ; advance to the next sample

; notice we do not clear datasum so we
; are starting the next group of samples
; at the point where the last left off

end while
--scott



Thanks,

Sean B


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
.

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