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avfilter/af_aiir: export normalize option

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And enable it in all modes by default.
This commit is contained in:
Paul B Mahol 2020-05-22 12:28:03 +02:00
parent 1fc5ddf774
commit ffda57b800
2 changed files with 40 additions and 1 deletions
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4
doc/filters.texi
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@ -1436,6 +1436,10 @@ single-precision floating-point
16-bit integers
@end table
@item n
Normalize filter coefficients, by default is enabled.
Enabling it will normalize magnitude response at DC to 0dB.
@item mix
How much to use filtered signal in output. Default is 1.
Range is between 0 and 1.

37
libavfilter/af_aiir.c
View File

@ -58,6 +58,7 @@ typedef struct AudioIIRContext {
char *a_str, *b_str, *g_str;
double dry_gain, wet_gain;
double mix;
int normalize;
int format;
int process;
int precision;
@ -430,6 +431,34 @@ static int expand(AVFilterContext *ctx, double *pz, int nb, double *coeffs)
return 0;
}
static void normalize_coeffs(AVFilterContext *ctx, int ch)
{
AudioIIRContext *s = ctx->priv;
IIRChannel *iir = &s->iir[ch];
double sum_den = 0.;
if (!s->normalize)
return;
for (int i = 0; i < iir->nb_ab[1]; i++) {
sum_den += iir->ab[1][i];
}
if (sum_den > 1e-6) {
double factor, sum_num = 0.;
for (int i = 0; i < iir->nb_ab[0]; i++) {
sum_num += iir->ab[0][i];
}
factor = sum_num / sum_den;
for (int i = 0; i < iir->nb_ab[1]; i++) {
iir->ab[1][i] *= factor;
}
}
}
static int convert_zp2tf(AVFilterContext *ctx, int channels)
{
AudioIIRContext *s = ctx->priv;
@ -466,6 +495,8 @@ static int convert_zp2tf(AVFilterContext *ctx, int channels)
}
iir->nb_ab[0]++;
normalize_coeffs(ctx, ch);
fail:
av_free(topc);
av_free(botc);
@ -601,7 +632,8 @@ static int decompose_zp2biquads(AVFilterContext *ctx, int channels)
iir->biquads[current_biquad].b[1] = b[2] / a[4];
iir->biquads[current_biquad].b[2] = b[0] / a[4];
if (fabs(iir->biquads[current_biquad].b[0] +
if (s->normalize &&
fabs(iir->biquads[current_biquad].b[0] +
iir->biquads[current_biquad].b[1] +
iir->biquads[current_biquad].b[2]) > 1e-6) {
factor = (iir->biquads[current_biquad].a[0] +
@ -1009,6 +1041,8 @@ static int config_output(AVFilterLink *outlink)
for (i = 0; i < iir->nb_ab[1]; i++) {
iir->ab[1][i] *= iir->g / iir->ab[0][0];
}
normalize_coeffs(ctx, ch);
}
switch (inlink->format) {
@ -1196,6 +1230,7 @@ static const AVOption aiir_options[] = {
{ "flt", "single-precision floating-point", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AF, "precision" },
{ "i32", "32-bit integers", 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, AF, "precision" },
{ "i16", "16-bit integers", 0, AV_OPT_TYPE_CONST, {.i64=3}, 0, 0, AF, "precision" },
{ "n", "normalize coefficients", OFFSET(normalize),AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, AF },
{ "mix", "set mix", OFFSET(mix), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 1, AF },
{ "response", "show IR frequency response", OFFSET(response), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, VF },
{ "channel", "set IR channel to display frequency response", OFFSET(ir_channel), AV_OPT_TYPE_INT, {.i64=0}, 0, 1024, VF },