avfilter: add audio emphasis filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2015-11-30 13:36:58 +01:00
parent 7234e04e35
commit 5d2cc00dd0
7 changed files with 446 additions and 1 deletions

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@ -40,6 +40,7 @@ version <next>:
- apulsator filter
- sidechaingate audio filter
- mipsdspr1 option has been renamed to mipsdsp
- aemphasis filter
version 2.8:

26
configure vendored
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@ -1051,6 +1051,21 @@ int main(void){ $func(); }
EOF
}
check_complexfunc(){
log check_complexfunc "$@"
func=$1
narg=$2
shift 2
test $narg = 2 && args="f, g" || args="f * I"
disable $func
check_ld "cc" "$@" <<EOF && enable $func
#include <complex.h>
#include <math.h>
float foo(complex float f, complex float g) { return $func($args); }
int main(void){ return (int) foo; }
EOF
}
check_mathfunc(){
log check_mathfunc "$@"
func=$1
@ -1768,6 +1783,11 @@ INTRINSICS_LIST="
intrinsics_neon
"
COMPLEX_FUNCS="
cabs
cexp
"
MATH_FUNCS="
atanf
atan2f
@ -1903,6 +1923,7 @@ HAVE_LIST="
$ARCH_FEATURES
$ATOMICS_LIST
$BUILTIN_LIST
$COMPLEX_FUNCS
$HAVE_LIST_CMDLINE
$HAVE_LIST_PUB
$HEADERS_LIST
@ -2785,6 +2806,7 @@ unix_protocol_deps="sys_un_h"
unix_protocol_select="network"
# filters
aemphasis_filter_deps="cabs cexp"
amovie_filter_deps="avcodec avformat"
aresample_filter_deps="swresample"
ass_filter_deps="libass"
@ -5324,6 +5346,10 @@ for func in $MATH_FUNCS; do
eval check_mathfunc $func \${${func}_args:-1}
done
for func in $COMPLEX_FUNCS; do
eval check_complexfunc $func \${${func}_args:-1}
done
# these are off by default, so fail if requested and not available
enabled avfoundation_indev && { check_header_oc AVFoundation/AVFoundation.h || disable avfoundation_indev; }
enabled avfoundation_indev && { check_lib2 CoreGraphics/CoreGraphics.h CGGetActiveDisplayList -framework CoreGraphics ||

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@ -528,6 +528,52 @@ aecho=0.8:0.9:1000|1800:0.3|0.25
@end example
@end itemize
@section aemphasis
Audio emphasis filter creates or restores material directly taken from LPs or
emphased CDs with different filter curves. E.g. to store music on vinyl the
signal has to be altered by a filter first to even out the disadvantages of
this recording medium.
Once the material is played back the inverse filter has to be applied to
restore the distortion of the frequency response.
The filter accepts the following options:
@table @option
@item level_in
Set input gain.
@item level_out
Set output gain.
@item mode
Set filter mode. For restoring material use @code{reproduction} mode, otherwise
use @code{production} mode. Default is @code{reproduction} mode.
@item type
Set filter type. Selects medium. Can be one of the following:
@table @option
@item col
select Columbia.
@item emi
select EMI.
@item bsi
select BSI (78RPM).
@item riaa
select RIAA.
@item cd
select Compact Disc (CD).
@item 50fm
select 50µs (FM).
@item 75fm
select 75µs (FM).
@item 50kf
select 50µs (FM-KF).
@item 75kf
select 75µs (FM-KF).
@end table
@end table
@section aeval
Modify an audio signal according to the specified expressions.

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@ -27,6 +27,7 @@ OBJS-$(CONFIG_ACOMPRESSOR_FILTER) += af_sidechaincompress.o
OBJS-$(CONFIG_ACROSSFADE_FILTER) += af_afade.o
OBJS-$(CONFIG_ADELAY_FILTER) += af_adelay.o
OBJS-$(CONFIG_AECHO_FILTER) += af_aecho.o
OBJS-$(CONFIG_AEMPHASIS_FILTER) += af_aemphasis.o
OBJS-$(CONFIG_AEVAL_FILTER) += aeval.o
OBJS-$(CONFIG_AFADE_FILTER) += af_afade.o
OBJS-$(CONFIG_AFORMAT_FILTER) += af_aformat.o

370
libavfilter/af_aemphasis.c Normal file
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@ -0,0 +1,370 @@
/*
* Copyright (c) 2001-2010 Krzysztof Foltman, Markus Schmidt, Thor Harald Johansen, Damien Zammit and others
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <complex.h>
#include "libavutil/opt.h"
#include "avfilter.h"
#include "internal.h"
#include "audio.h"
typedef struct BiquadCoeffs {
double a0, a1, a2, b1, b2;
} BiquadCoeffs;
typedef struct BiquadD2 {
double a0, a1, a2, b1, b2, w1, w2;
} BiquadD2;
typedef struct RIAACurve {
BiquadD2 r1;
BiquadD2 brickw;
int use_brickw;
} RIAACurve;
typedef struct AudioEmphasisContext {
const AVClass *class;
int mode, type;
double level_in, level_out;
RIAACurve *rc;
} AudioEmphasisContext;
#define OFFSET(x) offsetof(AudioEmphasisContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption aemphasis_options[] = {
{ "level_in", "set input gain", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 64, FLAGS },
{ "level_out", "set output gain", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 64, FLAGS },
{ "mode", "set filter mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS, "mode" },
{ "reproduction", NULL, 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "mode" },
{ "production", NULL, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "mode" },
{ "type", "set filter type", OFFSET(type), AV_OPT_TYPE_INT, {.i64=4}, 0, 8, FLAGS, "type" },
{ "col", "Columbia", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "type" },
{ "emi", "EMI", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "type" },
{ "bsi", "BSI (78RPM)", 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, FLAGS, "type" },
{ "riaa", "RIAA", 0, AV_OPT_TYPE_CONST, {.i64=3}, 0, 0, FLAGS, "type" },
{ "cd", "Compact Disc (CD)", 0, AV_OPT_TYPE_CONST, {.i64=4}, 0, 0, FLAGS, "type" },
{ "50fm", "50µs (FM)", 0, AV_OPT_TYPE_CONST, {.i64=5}, 0, 0, FLAGS, "type" },
{ "75fm", "75µs (FM)", 0, AV_OPT_TYPE_CONST, {.i64=6}, 0, 0, FLAGS, "type" },
{ "50kf", "50µs (FM-KF)", 0, AV_OPT_TYPE_CONST, {.i64=7}, 0, 0, FLAGS, "type" },
{ "75kf", "75µs (FM-KF)", 0, AV_OPT_TYPE_CONST, {.i64=8}, 0, 0, FLAGS, "type" },
{ NULL }
};
AVFILTER_DEFINE_CLASS(aemphasis);
static inline double biquad(BiquadD2 *bq, double in)
{
double n = in;
double tmp = n - bq->w1 * bq->b1 - bq->w2 * bq->b2;
double out = tmp * bq->a0 + bq->w1 * bq->a1 + bq->w2 * bq->a2;
bq->w2 = bq->w1;
bq->w1 = tmp;
return out;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
AudioEmphasisContext *s = ctx->priv;
const double *src = (const double *)in->data[0];
const double level_out = s->level_out;
const double level_in = s->level_in;
AVFrame *out;
double *dst;
int n, c;
if (av_frame_is_writable(in)) {
out = in;
} else {
out = ff_get_audio_buffer(inlink, in->nb_samples);
if (!out) {
av_frame_free(&in);
return AVERROR(ENOMEM);
}
av_frame_copy_props(out, in);
}
dst = (double *)out->data[0];
for (n = 0; n < in->nb_samples; n++) {
for (c = 0; c < inlink->channels; c++)
dst[c] = level_out * biquad(&s->rc[c].r1, s->rc[c].use_brickw ? biquad(&s->rc[c].brickw, src[c] * level_in) : src[c] * level_in);
dst += inlink->channels;
src += inlink->channels;
}
if (in != out)
av_frame_free(&in);
return ff_filter_frame(outlink, out);
}
static int query_formats(AVFilterContext *ctx)
{
AVFilterChannelLayouts *layouts;
AVFilterFormats *formats;
static const enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_DBL,
AV_SAMPLE_FMT_NONE
};
int ret;
layouts = ff_all_channel_counts();
if (!layouts)
return AVERROR(ENOMEM);
ret = ff_set_common_channel_layouts(ctx, layouts);
if (ret < 0)
return ret;
formats = ff_make_format_list(sample_fmts);
if (!formats)
return AVERROR(ENOMEM);
ret = ff_set_common_formats(ctx, formats);
if (ret < 0)
return ret;
formats = ff_all_samplerates();
if (!formats)
return AVERROR(ENOMEM);
return ff_set_common_samplerates(ctx, formats);
}
static inline void set_highshelf_rbj(BiquadD2 *bq, double freq, double q, double peak, double sr)
{
double A = sqrt(peak);
double w0 = freq * 2 * M_PI / sr;
double alpha = sin(w0) / (2 * q);
double cw0 = cos(w0);
double tmp = 2 * sqrt(A) * alpha;
double b0 = 0, ib0 = 0;
bq->a0 = A*( (A+1) + (A-1)*cw0 + tmp);
bq->a1 = -2*A*( (A-1) + (A+1)*cw0);
bq->a2 = A*( (A+1) + (A-1)*cw0 - tmp);
b0 = (A+1) - (A-1)*cw0 + tmp;
bq->b1 = 2*( (A-1) - (A+1)*cw0);
bq->b2 = (A+1) - (A-1)*cw0 - tmp;
ib0 = 1 / b0;
bq->b1 *= ib0;
bq->b2 *= ib0;
bq->a0 *= ib0;
bq->a1 *= ib0;
bq->a2 *= ib0;
}
static inline void set_lp_rbj(BiquadD2 *bq, double fc, double q, double sr, double gain)
{
double omega = 2.0 * M_PI * fc / sr;
double sn = sin(omega);
double cs = cos(omega);
double alpha = sn/(2 * q);
double inv = 1.0/(1.0 + alpha);
bq->a2 = bq->a0 = gain * inv * (1.0 - cs) * 0.5;
bq->a1 = bq->a0 + bq->a0;
bq->b1 = (-2.0 * cs * inv);
bq->b2 = ((1.0 - alpha) * inv);
}
static double freq_gain(BiquadCoeffs *c, double freq, double sr)
{
double complex z, w;
freq *= 2.0 * M_PI / sr;
w = 0 + I * freq;
z = 1.0 / cexp(w);
return cabs(((double complex)c->a0 + c->a1 * z + c->a2 * z*z) /
((double complex)1.0 + c->b1 * z + c->b2 * z*z));
}
static int config_input(AVFilterLink *inlink)
{
double i, j, k, g, t, a0, a1, a2, b1, b2, tau1, tau2, tau3;
double cutfreq, gain1kHz, gc, sr = inlink->sample_rate;
AVFilterContext *ctx = inlink->dst;
AudioEmphasisContext *s = ctx->priv;
BiquadCoeffs coeffs;
int ch;
s->rc = av_calloc(inlink->channels, sizeof(*s->rc));
if (!s->rc)
return AVERROR(ENOMEM);
switch (s->type) {
case 0: //"Columbia"
i = 100.;
j = 500.;
k = 1590.;
break;
case 1: //"EMI"
i = 70.;
j = 500.;
k = 2500.;
break;
case 2: //"BSI(78rpm)"
i = 50.;
j = 353.;
k = 3180.;
break;
case 3: //"RIAA"
default:
tau1 = 0.003180;
tau2 = 0.000318;
tau3 = 0.000075;
i = 1. / (2. * M_PI * tau1);
j = 1. / (2. * M_PI * tau2);
k = 1. / (2. * M_PI * tau3);
break;
case 4: //"CD Mastering"
tau1 = 0.000050;
tau2 = 0.000015;
tau3 = 0.0000001;// 1.6MHz out of audible range for null impact
i = 1. / (2. * M_PI * tau1);
j = 1. / (2. * M_PI * tau2);
k = 1. / (2. * M_PI * tau3);
break;
case 5: //"50µs FM (Europe)"
tau1 = 0.000050;
tau2 = tau1 / 20;// not used
tau3 = tau1 / 50;//
i = 1. / (2. * M_PI * tau1);
j = 1. / (2. * M_PI * tau2);
k = 1. / (2. * M_PI * tau3);
break;
case 6: //"75µs FM (US)"
tau1 = 0.000075;
tau2 = tau1 / 20;// not used
tau3 = tau1 / 50;//
i = 1. / (2. * M_PI * tau1);
j = 1. / (2. * M_PI * tau2);
k = 1. / (2. * M_PI * tau3);
break;
}
i *= 2 * M_PI;
j *= 2 * M_PI;
k *= 2 * M_PI;
t = 1. / sr;
//swap a1 b1, a2 b2
if (s->type == 7 || s->type == 8) {
s->rc[0].use_brickw = 0;
double tau = (s->type == 7 ? 0.000050 : 0.000075);
double f = 1.0 / (2 * M_PI * tau);
double nyq = sr * 0.5;
double gain = sqrt(1.0 + nyq * nyq / (f * f)); // gain at Nyquist
double cfreq = sqrt((gain - 1.0) * f * f); // frequency
double q = 1.0;
if (s->type == 8)
q = pow((sr / 3269.0) + 19.5, -0.25); // somewhat poor curve-fit
if (s->type == 7)
q = pow((sr / 4750.0) + 19.5, -0.25);
if (s->mode == 0)
set_highshelf_rbj(&s->rc[0].r1, cfreq, q, 1. / gain, sr);
else
set_highshelf_rbj(&s->rc[0].r1, cfreq, q, gain, sr);
} else {
s->rc[0].use_brickw = 1;
if (s->mode == 0) { // Reproduction
g = 1. / (4.+2.*i*t+2.*k*t+i*k*t*t);
a0 = (2.*t+j*t*t)*g;
a1 = (2.*j*t*t)*g;
a2 = (-2.*t+j*t*t)*g;
b1 = (-8.+2.*i*k*t*t)*g;
b2 = (4.-2.*i*t-2.*k*t+i*k*t*t)*g;
} else { // Production
g = 1. / (2.*t+j*t*t);
a0 = (4.+2.*i*t+2.*k*t+i*k*t*t)*g;
a1 = (-8.+2.*i*k*t*t)*g;
a2 = (4.-2.*i*t-2.*k*t+i*k*t*t)*g;
b1 = (2.*j*t*t)*g;
b2 = (-2.*t+j*t*t)*g;
}
coeffs.a0 = a0;
coeffs.a1 = a1;
coeffs.a2 = a2;
coeffs.b1 = b1;
coeffs.b2 = b2;
// the coeffs above give non-normalized value, so it should be normalized to produce 0dB at 1 kHz
// find actual gain
// Note: for FM emphasis, use 100 Hz for normalization instead
gain1kHz = freq_gain(&coeffs, 1000.0, sr);
// divide one filter's x[n-m] coefficients by that value
gc = 1.0 / gain1kHz;
s->rc[0].r1.a0 = coeffs.a0 * gc;
s->rc[0].r1.a1 = coeffs.a1 * gc;
s->rc[0].r1.a2 = coeffs.a2 * gc;
s->rc[0].r1.b1 = coeffs.b1;
s->rc[0].r1.b2 = coeffs.b2;
}
cutfreq = FFMIN(0.45 * sr, 21000.);
set_lp_rbj(&s->rc[0].brickw, cutfreq, 0.707, sr, 1.);
for (ch = 1; ch < inlink->channels; ch++) {
memcpy(&s->rc[ch], &s->rc[0], sizeof(RIAACurve));
}
return 0;
}
static av_cold void uninit(AVFilterContext *ctx)
{
AudioEmphasisContext *s = ctx->priv;
av_freep(&s->rc);
}
static const AVFilterPad avfilter_af_aemphasis_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_input,
.filter_frame = filter_frame,
},
{ NULL }
};
static const AVFilterPad avfilter_af_aemphasis_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
},
{ NULL }
};
AVFilter ff_af_aemphasis = {
.name = "aemphasis",
.description = NULL_IF_CONFIG_SMALL("Audio emphasis."),
.priv_size = sizeof(AudioEmphasisContext),
.priv_class = &aemphasis_class,
.uninit = uninit,
.query_formats = query_formats,
.inputs = avfilter_af_aemphasis_inputs,
.outputs = avfilter_af_aemphasis_outputs,
};

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@ -49,6 +49,7 @@ void avfilter_register_all(void)
REGISTER_FILTER(ACROSSFADE, acrossfade, af);
REGISTER_FILTER(ADELAY, adelay, af);
REGISTER_FILTER(AECHO, aecho, af);
REGISTER_FILTER(AEMPHASIS, aemphasis, af);
REGISTER_FILTER(AEVAL, aeval, af);
REGISTER_FILTER(AFADE, afade, af);
REGISTER_FILTER(AFORMAT, aformat, af);

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@ -30,7 +30,7 @@
#include "libavutil/version.h"
#define LIBAVFILTER_VERSION_MAJOR 6
#define LIBAVFILTER_VERSION_MINOR 19
#define LIBAVFILTER_VERSION_MINOR 20
#define LIBAVFILTER_VERSION_MICRO 100
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \