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avfilter: add hilbert source FIR filter 

Signed-off-by: Paul B Mahol <onemda@gmail.com>
tags/n4.0
Paul B Mahol 8 years ago
parent
695b1d8111
commit
89bbf5c7ec
6 changed files with 231 additions and 1 deletions
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  1. +1
    -0
      Changelog
  2. +28
    -0
      doc/filters.texi
  3. +1
    -0
      libavfilter/Makefile
  4. +1
    -0
      libavfilter/allfilters.c
  5. +199
    -0
      libavfilter/asrc_hilbert.c
  6. +1
    -1
      libavfilter/version.h

+ 1
- 0
Changelog View File

@@ -32,6 +32,7 @@ version <next>:
version is Windows Vista.
- deconvolve video filter
- entropy video filter
- hilbert audio filter source


version 3.4:


+ 28
- 0
doc/filters.texi View File

@@ -926,6 +926,7 @@ afftfilt="1-clip((b/nb)*b,0,1)"
@end example
@end itemize

@anchor{afir}
@section afir

Apply an arbitrary Frequency Impulse Response filter.
@@ -4873,6 +4874,33 @@ anoisesrc=d=60:c=pink:r=44100:a=0.5
@end example
@end itemize

@section hilbert

Generate odd-tap Hilbert transform FIR coefficients.

The resulting stream can be used with @ref{afir} filter for phase-shifting
the signal by 90 degrees.

This is used in many matrix coding schemes and for analytic signal generation.
The process is often written as a multiplication by i (or j), the imaginary unit.

The filter accepts the following options:

@table @option

@item sample_rate, s
Set sample rate, default is 44100.

@item taps, t
Set length of FIR filter, default is 22051.

@item nb_samples, n
Set number of samples per each frame.

@item win_func, w
Set window function to be used when generating FIR coefficients.
@end table

@section sine

Generate an audio signal made of a sine wave with amplitude 1/8.


+ 1
- 0
libavfilter/Makefile View File

@@ -126,6 +126,7 @@ OBJS-$(CONFIG_AEVALSRC_FILTER) += aeval.o
OBJS-$(CONFIG_ANOISESRC_FILTER) += asrc_anoisesrc.o
OBJS-$(CONFIG_ANULLSRC_FILTER) += asrc_anullsrc.o
OBJS-$(CONFIG_FLITE_FILTER) += asrc_flite.o
OBJS-$(CONFIG_HILBERT_FILTER) += asrc_hilbert.o
OBJS-$(CONFIG_SINE_FILTER) += asrc_sine.o

OBJS-$(CONFIG_ANULLSINK_FILTER) += asink_anullsink.o


+ 1
- 0
libavfilter/allfilters.c View File

@@ -137,6 +137,7 @@ static void register_all(void)
REGISTER_FILTER(ANOISESRC, anoisesrc, asrc);
REGISTER_FILTER(ANULLSRC, anullsrc, asrc);
REGISTER_FILTER(FLITE, flite, asrc);
REGISTER_FILTER(HILBERT, hilbert, asrc);
REGISTER_FILTER(SINE, sine, asrc);

REGISTER_FILTER(ANULLSINK, anullsink, asink);


+ 199
- 0
libavfilter/asrc_hilbert.c View File

@@ -0,0 +1,199 @@
/*
* Copyright (c) 2018 Paul B Mahol
*
* 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 "libavutil/opt.h"
#include "audio.h"
#include "avfilter.h"
#include "internal.h"
#include "window_func.h"

typedef struct HilbertContext {
const AVClass *class;

int sample_rate;
int nb_taps;
int nb_samples;
int win_func;

float *taps;
int64_t pts;
} HilbertContext;

#define OFFSET(x) offsetof(HilbertContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

static const AVOption hilbert_options[] = {
{ "sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, INT_MAX, FLAGS },
{ "r", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, INT_MAX, FLAGS },
{ "taps", "set number of taps", OFFSET(nb_taps), AV_OPT_TYPE_INT, {.i64=22051}, 11, UINT16_MAX, FLAGS },
{ "t", "set number of taps", OFFSET(nb_taps), AV_OPT_TYPE_INT, {.i64=22051}, 11, UINT16_MAX, FLAGS },
{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, INT_MAX, FLAGS },
{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, INT_MAX, FLAGS },
{ "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64=WFUNC_BLACKMAN}, 0, NB_WFUNC-1, FLAGS, "win_func" },
{ "w", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64=WFUNC_BLACKMAN}, 0, NB_WFUNC-1, FLAGS, "win_func" },
{ "rect", "Rectangular", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT}, 0, 0, FLAGS, "win_func" },
{ "bartlett", "Bartlett", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, FLAGS, "win_func" },
{ "hanning", "Hanning", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING}, 0, 0, FLAGS, "win_func" },
{ "hamming", "Hamming", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING}, 0, 0, FLAGS, "win_func" },
{ "blackman", "Blackman", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, FLAGS, "win_func" },
{ "welch", "Welch", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH}, 0, 0, FLAGS, "win_func" },
{ "flattop", "Flat-top", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP}, 0, 0, FLAGS, "win_func" },
{ "bharris", "Blackman-Harris", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS}, 0, 0, FLAGS, "win_func" },
{ "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, FLAGS, "win_func" },
{ "bhann", "Bartlett-Hann", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN}, 0, 0, FLAGS, "win_func" },
{ "sine", "Sine", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE}, 0, 0, FLAGS, "win_func" },
{ "nuttall", "Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL}, 0, 0, FLAGS, "win_func" },
{ "lanczos", "Lanczos", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS}, 0, 0, FLAGS, "win_func" },
{ "gauss", "Gauss", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS}, 0, 0, FLAGS, "win_func" },
{ "tukey", "Tukey", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY}, 0, 0, FLAGS, "win_func" },
{ "dolph", "Dolph-Chebyshev", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH}, 0, 0, FLAGS, "win_func" },
{ "cauchy", "Cauchy", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY}, 0, 0, FLAGS, "win_func" },
{ "parzen", "Parzen", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN}, 0, 0, FLAGS, "win_func" },
{ "poisson", "Poisson", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON}, 0, 0, FLAGS, "win_func" },
{NULL}
};

AVFILTER_DEFINE_CLASS(hilbert);

static av_cold int init(AVFilterContext *ctx)
{
HilbertContext *s = ctx->priv;

if (!(s->nb_taps & 1)) {
av_log(s, AV_LOG_ERROR, "Number of taps %d must be odd length.\n", s->nb_taps);
return AVERROR(EINVAL);
}

return 0;
}

static av_cold void uninit(AVFilterContext *ctx)
{
HilbertContext *s = ctx->priv;

av_freep(&s->taps);
}

static av_cold int query_formats(AVFilterContext *ctx)
{
HilbertContext *s = ctx->priv;
static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
int sample_rates[] = { s->sample_rate, -1 };
static const enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_FLT,
AV_SAMPLE_FMT_NONE
};

AVFilterFormats *formats;
AVFilterChannelLayouts *layouts;
int 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;

layouts = avfilter_make_format64_list(chlayouts);
if (!layouts)
return AVERROR(ENOMEM);
ret = ff_set_common_channel_layouts(ctx, layouts);
if (ret < 0)
return ret;

formats = ff_make_format_list(sample_rates);
if (!formats)
return AVERROR(ENOMEM);
return ff_set_common_samplerates(ctx, formats);
}

static av_cold int config_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
HilbertContext *s = ctx->priv;
float overlap;
int i;

s->taps = av_malloc_array(s->nb_taps, sizeof(*s->taps));
if (!s->taps)
return AVERROR(ENOMEM);

generate_window_func(s->taps, s->nb_taps, s->win_func, &overlap);

for (i = 0; i < s->nb_taps; i++) {
int k = -(s->nb_taps / 2) + i;

if (k & 1) {
float pk = M_PI * k;

s->taps[i] *= (1.f - cosf(pk)) / pk;
} else {
s->taps[i] = 0.f;
}
}

s->pts = 0;

return 0;
}

static int request_frame(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
HilbertContext *s = ctx->priv;
AVFrame *frame;
int nb_samples;

nb_samples = FFMIN(s->nb_samples, s->nb_taps - s->pts);
if (!nb_samples)
return AVERROR_EOF;

if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
return AVERROR(ENOMEM);

memcpy(frame->data[0], s->taps + s->pts, nb_samples * sizeof(float));

frame->pts = s->pts;
s->pts += nb_samples;
return ff_filter_frame(outlink, frame);
}

static const AVFilterPad hilbert_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.request_frame = request_frame,
.config_props = config_props,
},
{ NULL }
};

AVFilter ff_asrc_hilbert = {
.name = "hilbert",
.description = NULL_IF_CONFIG_SMALL("Generate a Hilbert transform FIR coefficients."),
.query_formats = query_formats,
.init = init,
.uninit = uninit,
.priv_size = sizeof(HilbertContext),
.inputs = NULL,
.outputs = hilbert_outputs,
.priv_class = &hilbert_class,
};

+ 1
- 1
libavfilter/version.h View File

@@ -30,7 +30,7 @@
#include "libavutil/version.h"

#define LIBAVFILTER_VERSION_MAJOR 7
#define LIBAVFILTER_VERSION_MINOR 9
#define LIBAVFILTER_VERSION_MINOR 10
#define LIBAVFILTER_VERSION_MICRO 100

#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \


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