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Split out Butterworth filter coeff init to a separate function. 

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Justin Ruggles 2011-01-20 19:06:15 +00:00 committed by Mans Rullgard
parent 75b98610a7
commit 30112adadf
1 changed files with 46 additions and 18 deletions
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64
libavcodec/iirfilter.c
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@ -47,29 +47,25 @@ typedef struct FFIIRFilterState{
/// maximum supported filter order
#define MAXORDER 30
av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc,
enum IIRFilterType filt_type,
enum IIRFilterMode filt_mode,
int order, float cutoff_ratio,
float stopband, float ripple)
static int butterworth_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c,
enum IIRFilterMode filt_mode,
int order, float cutoff_ratio,
float stopband)
{
int i, j;
FFIIRFilterCoeffs *c;
double wa;
double p[MAXORDER + 1][2];
if(filt_type != FF_FILTER_TYPE_BUTTERWORTH || filt_mode != FF_FILTER_MODE_LOWPASS)
return NULL;
if(order <= 1 || (order & 1) || order > MAXORDER || cutoff_ratio >= 1.0)
return NULL;
FF_ALLOCZ_OR_GOTO(avc, c, sizeof(FFIIRFilterCoeffs),
init_fail);
FF_ALLOC_OR_GOTO (avc, c->cx, sizeof(c->cx[0]) * ((order >> 1) + 1),
init_fail);
FF_ALLOC_OR_GOTO (avc, c->cy, sizeof(c->cy[0]) * order,
init_fail);
c->order = order;
if (filt_mode != FF_FILTER_MODE_LOWPASS) {
av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
"low-pass filter mode\n");
return -1;
}
if (order & 1) {
av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
"even filter orders\n");
return -1;
}
wa = 2 * tan(M_PI * 0.5 * cutoff_ratio);
@ -113,6 +109,38 @@ av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc,
}
c->gain /= 1 << order;
return 0;
}
av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc,
enum IIRFilterType filt_type,
enum IIRFilterMode filt_mode,
int order, float cutoff_ratio,
float stopband, float ripple)
{
FFIIRFilterCoeffs *c;
if (order <= 0 || order > MAXORDER || cutoff_ratio >= 1.0)
return NULL;
FF_ALLOCZ_OR_GOTO(avc, c, sizeof(FFIIRFilterCoeffs),
init_fail);
FF_ALLOC_OR_GOTO (avc, c->cx, sizeof(c->cx[0]) * ((order >> 1) + 1),
init_fail);
FF_ALLOC_OR_GOTO (avc, c->cy, sizeof(c->cy[0]) * order,
init_fail);
c->order = order;
if (filt_type == FF_FILTER_TYPE_BUTTERWORTH) {
if (butterworth_init_coeffs(avc, c, filt_mode, order, cutoff_ratio,
stopband)) {
goto init_fail;
}
} else {
av_log(avc, AV_LOG_ERROR, "filter type is not currently implemented\n");
goto init_fail;
}
return c;
init_fail: