/**
* Initialize a resampler object
*
* @param rs Resampler to initialize
*/
void auresamp_init(struct auresamp *rs)
{
if (!rs)
return;
memset(rs, 0, sizeof(*rs));
fir_reset(&rs->fir);
}
struct fir_filter * fir_init(const float *taps, size_t length)
{
struct fir_filter *filt;
filt = calloc(1, sizeof(filt[0]));
if (!filt) {
perror("calloc");
return NULL;
}
/* Filter state is a sliding window implemented with 2 copies of data */
filt->i = calloc(2 * length, sizeof(filt->i[0]));
if (!filt->i) {
perror("calloc");
fir_deinit(filt);
return NULL;
}
filt->q = calloc(2 * length, sizeof(filt->q[0]));
if (!filt->i) {
perror("calloc");
fir_deinit(filt);
return NULL;
}
filt->taps = calloc(length, sizeof(filt->taps[0]));
if (!filt->taps) {
perror("calloc");
fir_deinit(filt);
return NULL;
}
memcpy(filt->taps, taps, length * sizeof(filt->taps[0]));
filt->length = length;
fir_reset(filt);
return filt;
}
/**
* Configure a resampler object
*
* @note The sample rate ratio must be an integer
*
* @param rs Resampler
* @param irate Input sample rate
* @param ich Input channel count
* @param orate Output sample rate
* @param och Output channel count
*
* @return 0 if success, otherwise error code
*/
int auresamp_setup(struct auresamp *rs, uint32_t irate, unsigned ich,
uint32_t orate, unsigned och)
{
if (!rs || !irate || !ich || !orate || !och)
return EINVAL;
if (orate == irate && och == ich) {
auresamp_init(rs);
return 0;
}
if (orate >= irate) {
if (orate % irate)
return ENOTSUP;
if (ich == 1 && och == 1)
rs->resample = upsample_mono2mono;
else if (ich == 1 && och == 2)
rs->resample = upsample_mono2stereo;
else if (ich == 2 && och == 1)
rs->resample = upsample_stereo2mono;
else if (ich == 2 && och == 2)
rs->resample = upsample_stereo2stereo;
else
return ENOTSUP;
if (!rs->up || orate != rs->orate || och != rs->och)
fir_reset(&rs->fir);
rs->ratio = orate / irate;
rs->up = true;
if (orate == 48000 && irate == 16000) {
rs->tapv = fir_48_8;
rs->tapc = ARRAY_SIZE(fir_48_8);
}
else {
rs->tapv = fir_48_4;
rs->tapc = ARRAY_SIZE(fir_48_4);
}
}
else {
if (irate % orate)
return ENOTSUP;
if (ich == 1 && och == 1)
rs->resample = downsample_mono2mono;
else if (ich == 1 && och == 2)
rs->resample = downsample_mono2stereo;
else if (ich == 2 && och == 1)
rs->resample = downsample_stereo2mono;
else if (ich == 2 && och == 2)
rs->resample = downsample_stereo2stereo;
else
return ENOTSUP;
if (rs->up || irate != rs->irate || ich != rs->ich)
fir_reset(&rs->fir);
rs->ratio = irate / orate;
rs->up = false;
if (irate == 48000 && orate == 16000) {
rs->tapv = fir_48_8;
rs->tapc = ARRAY_SIZE(fir_48_8);
}
else {
rs->tapv = fir_48_4;
rs->tapc = ARRAY_SIZE(fir_48_4);
}
}
rs->orate = orate;
rs->och = och;
rs->irate = irate;
rs->ich = ich;
return 0;
}
