From 30112adadf06fe2f9500e4da365eb8a58095c940 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Thu, 20 Jan 2011 19:06:15 +0000 Subject: Split out Butterworth filter coeff init to a separate function. Signed-off-by: Mans Rullgard --- libavcodec/iirfilter.c | 64 ++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 46 insertions(+), 18 deletions(-) (limited to 'libavcodec/iirfilter.c') diff --git a/libavcodec/iirfilter.c b/libavcodec/iirfilter.c index 38c0808b90..c0ac947289 100644 --- a/libavcodec/iirfilter.c +++ b/libavcodec/iirfilter.c @@ -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: -- cgit v1.2.3