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avfilter/af_tremolo: make it bit-exact with sox effect of same name

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Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2015-09-23 23:03:35 +02:00
parent 7179add427
commit 964a9badcc
2 changed files with 23 additions and 24 deletions
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2
libavfilter/Makefile
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@ -85,7 +85,7 @@ OBJS-$(CONFIG_SILENCEREMOVE_FILTER) += af_silenceremove.o
OBJS-$(CONFIG_STEREOTOOLS_FILTER) += af_stereotools.o
OBJS-$(CONFIG_STEREOWIDEN_FILTER) += af_stereowiden.o
OBJS-$(CONFIG_TREBLE_FILTER) += af_biquads.o
OBJS-$(CONFIG_TREMOLO_FILTER) += af_tremolo.o generate_wave_table.o
OBJS-$(CONFIG_TREMOLO_FILTER) += af_tremolo.o
OBJS-$(CONFIG_VOLUME_FILTER) += af_volume.o
OBJS-$(CONFIG_VOLUMEDETECT_FILTER) += af_volumedetect.o

45
libavfilter/af_tremolo.c
View File

@ -22,15 +22,13 @@
#include "avfilter.h"
#include "internal.h"
#include "audio.h"
#include "generate_wave_table.h"
typedef struct TremoloContext {
const AVClass *class;
double freq;
double depth;
double *wave_table;
int wave_table_index;
int sample_rate;
double *table;
int index;
} TremoloContext;
#define OFFSET(x) offsetof(TremoloContext, x)
@ -44,20 +42,11 @@ static const AVOption tremolo_options[] = {
AVFILTER_DEFINE_CLASS(tremolo);
static double trem_env(AVFilterContext *ctx)
{
TremoloContext *s = ctx->priv;
double env = s->wave_table[s->wave_table_index];
s->wave_table_index++;
if (s->wave_table_index >= s->sample_rate / s->freq)
s->wave_table_index = 0;
return 1.0 - (s->depth * env);
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
TremoloContext *s = ctx->priv;
const double *src = (const double *)in->data[0];
const int channels = inlink->channels;
const int nb_samples = in->nb_samples;
@ -78,12 +67,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
dst = (double *)out->data[0];
for (n = 0; n < nb_samples; n++) {
const double env = trem_env(ctx);
for (c = 0; c < channels; c++)
dst[c] = src[c] * env;
dst[c] = src[c] * s->table[s->index];
dst += channels;
src += channels;
s->index++;
if (s->index >= inlink->sample_rate)
s->index = 0;
}
if (in != out)
@ -125,21 +115,30 @@ static int query_formats(AVFilterContext *ctx)
static av_cold void uninit(AVFilterContext *ctx)
{
TremoloContext *s = ctx->priv;
av_freep(&s->wave_table);
av_freep(&s->table);
}
static int config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
TremoloContext *s = ctx->priv;
const double offset = 1. - s->depth / 2.;
int i;
s->sample_rate = inlink->sample_rate;
s->wave_table = av_malloc_array(s->sample_rate / s->freq, sizeof(*s->wave_table));
if (!s->wave_table)
s->table = av_malloc_array(inlink->sample_rate, sizeof(*s->table));
if (!s->table)
return AVERROR(ENOMEM);
ff_generate_wave_table(WAVE_SIN, AV_SAMPLE_FMT_DBL, s->wave_table, s->sample_rate / s->freq, 0.0, 1.0, 0.0);
s->wave_table_index = 0;
for (i = 0; i < inlink->sample_rate; i++) {
double env = s->freq * i / inlink->sample_rate;
env = sin(2 * M_PI * fmod(env + 0.25, 1.0));
s->table[i] = env * (1 - fabs(offset)) + offset;
}
s->index = 0;
return 0;
}