16Apr2003 Steve Kann <stevek@stevek.com>
The code in resample.c/resample.h has been liberally yanked from the SoX
distribution, and reworked just a tiny bit to allow compilation outside
of SoX.
Aside from some minor changes to the calling conventions (to use just
the private resample data structure, not the larget sox structures), and
generic code moves/defines that needed to be localized, the other
notable changes are:
1) st_sample_t is here defined as a 16 bit integer, and not a 32 bit
integer, so this code will will be able to operate over 16 bit unsigned
samples (the resample effect works with floating point internally
anyway, so it was a small change in the code).
2) The "getopts" call is not necessary (nor, at this point helpful,
since the options are set to their default now ad the beginning of
start).
3) start now takes two additional parameters, "inrate" and "outrate"
To use this, the basic idea is:
st_resample_t resampler;
st_resample_start(&resampler, inrate, outrate);
while(you have input data)
{
iNum = (number of Input samples we have);
oNum = (size of Output buffer available)
iBuf = input buffer;
oBuf = output buffer;
if(st_resample_flow(&resampler, ibuf, obuf, &iNum, &oNum) != ST_SUCCESS)
{
handle error.
}
(after calling, iNum, oNum will the the count of buffers
read/written)
}
finally, you call st_sample_drain, to get the "last" output;
if(st_sample_drain(&resampler, obuf, &oNum) != ST_SUCCESS)
{
error
}
Then, call st_sample_stop, to free resources:
st_sample_stop(&resampler);
For a discussion on this and other resampling algorithms, see this page for a
great analysis by K. Bradley and Andreas Wilde at:
http://leute.server.de/wilde/resample.html
