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lavfi: add compand audio filter 

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Andrew Kelley 2014-02-26 01:47:40 -05:00 committed by Anton Khirnov
parent 4ec336484d
commit 738f83582a
6 changed files with 668 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Changelog
View File

@ -1,6 +1,10 @@
Entries are sorted chronologically from oldest to youngest within each release,
releases are sorted from youngest to oldest.
version <next>:
- compand audio filter
version 10:
- av_strnstr
- support ID3v2 tags in ASF files

73
doc/filters.texi
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@ -467,6 +467,79 @@ To fix a 5.1 WAV improperly encoded in AAC's native channel order
avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
@end example
@section compand
Compress or expand audio dynamic range.
A description of the accepted options follows.
@table @option
@item attacks
@item decays
Set list of times in seconds for each channel over which the instantaneous level
of the input signal is averaged to determine its volume. @var{attacks} refers to
increase of volume and @var{decays} refers to decrease of volume. For most
situations, the attack time (response to the audio getting louder) should be
shorter than the decay time because the human ear is more sensitive to sudden
loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
a typical value for decay is 0.8 seconds.
@item points
Set list of points for the transfer function, specified in dB relative to the
maximum possible signal amplitude. Each key points list must be defined using
the following syntax: @code{x0/y0|x1/y1|x2/y2|....}
The input values must be in strictly increasing order but the transfer function
does not have to be monotonically rising. The point @code{0/0} is assumed but
may be overridden (by @code{0/out-dBn}). Typical values for the transfer
function are @code{-70/-70|-60/-20}.
@item soft-knee
Set the curve radius in dB for all joints. Defaults to 0.01.
@item gain
Set additional gain in dB to be applied at all points on the transfer function.
This allows easy adjustment of the overall gain. Defaults to 0.
@item volume
Set initial volume in dB to be assumed for each channel when filtering starts.
This permits the user to supply a nominal level initially, so that, for
example, a very large gain is not applied to initial signal levels before the
companding has begun to operate. A typical value for audio which is initially
quiet is -90 dB. Defaults to 0.
@item delay
Set delay in seconds. The input audio is analyzed immediately, but audio is
delayed before being fed to the volume adjuster. Specifying a delay
approximately equal to the attack/decay times allows the filter to effectively
operate in predictive rather than reactive mode. Defaults to 0.
@end table
@subsection Examples
@itemize
@item
Make music with both quiet and loud passages suitable for listening in a noisy
environment:
@example
compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
@end example
@item
Noise gate for when the noise is at a lower level than the signal:
@example
compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
@end example
@item
Here is another noise gate, this time for when the noise is at a higher level
than the signal (making it, in some ways, similar to squelch):
@example
compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
@end example
@end itemize
@section join
Join multiple input streams into one multi-channel stream.

1
libavfilter/Makefile
View File

@ -34,6 +34,7 @@ OBJS-$(CONFIG_ASYNCTS_FILTER) += af_asyncts.o
OBJS-$(CONFIG_ATRIM_FILTER) += trim.o
OBJS-$(CONFIG_CHANNELMAP_FILTER) += af_channelmap.o
OBJS-$(CONFIG_CHANNELSPLIT_FILTER) += af_channelsplit.o
OBJS-$(CONFIG_COMPAND_FILTER) += af_compand.o
OBJS-$(CONFIG_JOIN_FILTER) += af_join.o
OBJS-$(CONFIG_RESAMPLE_FILTER) += af_resample.o
OBJS-$(CONFIG_VOLUME_FILTER) += af_volume.o

587
libavfilter/af_compand.c Normal file
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@ -0,0 +1,587 @@
/*
* Copyright (c) 1999 Chris Bagwell
* Copyright (c) 1999 Nick Bailey
* Copyright (c) 2007 Rob Sykes <robs@users.sourceforge.net>
* Copyright (c) 2013 Paul B Mahol
* Copyright (c) 2014 Andrew Kelley
*
* This file is part of libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* audio compand filter
*/
#include <string.h>
#include "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "libavutil/mathematics.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "audio.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
typedef struct ChanParam {
float attack;
float decay;
float volume;
} ChanParam;
typedef struct CompandSegment {
float x, y;
float a, b;
} CompandSegment;
typedef struct CompandContext {
const AVClass *class;
int nb_channels;
int nb_segments;
char *attacks, *decays, *points;
CompandSegment *segments;
ChanParam *channels;
float in_min_lin;
float out_min_lin;
double curve_dB;
double gain_dB;
double initial_volume;
double delay;
AVFrame *delay_frame;
int delay_samples;
int delay_count;
int delay_index;
int64_t pts;
int (*compand)(AVFilterContext *ctx, AVFrame *frame);
} CompandContext;
#define OFFSET(x) offsetof(CompandContext, x)
#define A AV_OPT_FLAG_AUDIO_PARAM
static const AVOption compand_options[] = {
{ "attacks", "set time over which increase of volume is determined", OFFSET(attacks), AV_OPT_TYPE_STRING, { .str = "0.3" }, 0, 0, A },
{ "decays", "set time over which decrease of volume is determined", OFFSET(decays), AV_OPT_TYPE_STRING, { .str = "0.8" }, 0, 0, A },
{ "points", "set points of transfer function", OFFSET(points), AV_OPT_TYPE_STRING, { .str = "-70/-70|-60/-20" }, 0, 0, A },
{ "soft-knee", "set soft-knee", OFFSET(curve_dB), AV_OPT_TYPE_DOUBLE, { .dbl = 0.01 }, 0.01, 900, A },
{ "gain", "set output gain", OFFSET(gain_dB), AV_OPT_TYPE_DOUBLE, { .dbl = 0 }, -900, 900, A },
{ "volume", "set initial volume", OFFSET(initial_volume), AV_OPT_TYPE_DOUBLE, { .dbl = 0 }, -900, 0, A },
{ "delay", "set delay for samples before sending them to volume adjuster", OFFSET(delay), AV_OPT_TYPE_DOUBLE, { .dbl = 0 }, 0, 20, A },
{ NULL }
};
static const AVClass compand_class = {
.class_name = "compand filter",
.item_name = av_default_item_name,
.option = compand_options,
.version = LIBAVUTIL_VERSION_INT,
};
static av_cold int init(AVFilterContext *ctx)
{
CompandContext *s = ctx->priv;
s->pts = AV_NOPTS_VALUE;
return 0;
}
static av_cold void uninit(AVFilterContext *ctx)
{
CompandContext *s = ctx->priv;
av_freep(&s->channels);
av_freep(&s->segments);
av_frame_free(&s->delay_frame);
}
static int query_formats(AVFilterContext *ctx)
{
AVFilterChannelLayouts *layouts;
AVFilterFormats *formats;
static const enum AVSampleFormat sample_fmts[] = {
AV_SAMPLE_FMT_FLTP,
AV_SAMPLE_FMT_NONE
};
layouts = ff_all_channel_layouts();
if (!layouts)
return AVERROR(ENOMEM);
ff_set_common_channel_layouts(ctx, layouts);
formats = ff_make_format_list(sample_fmts);
if (!formats)
return AVERROR(ENOMEM);
ff_set_common_formats(ctx, formats);
formats = ff_all_samplerates();
if (!formats)
return AVERROR(ENOMEM);
ff_set_common_samplerates(ctx, formats);
return 0;
}
static void count_items(char *item_str, int *nb_items)
{
char *p;
*nb_items = 1;
for (p = item_str; *p; p++) {
if (*p == '|')
(*nb_items)++;
}
}
static void update_volume(ChanParam *cp, float in)
{
float delta = in - cp->volume;
if (delta > 0.0)
cp->volume += delta * cp->attack;
else
cp->volume += delta * cp->decay;
}
static float get_volume(CompandContext *s, float in_lin)
{
CompandSegment *cs;
float in_log, out_log;
int i;
if (in_lin < s->in_min_lin)
return s->out_min_lin;
in_log = logf(in_lin);
for (i = 1; i < s->nb_segments; i++)
if (in_log <= s->segments[i].x)
break;
cs = &s->segments[i - 1];
in_log -= cs->x;
out_log = cs->y + in_log * (cs->a * in_log + cs->b);
return expf(out_log);
}
static int compand_nodelay(AVFilterContext *ctx, AVFrame *frame)
{
CompandContext *s = ctx->priv;
AVFilterLink *inlink = ctx->inputs[0];
const int channels = s->nb_channels;
const int nb_samples = frame->nb_samples;
AVFrame *out_frame;
int chan, i;
int err;
if (av_frame_is_writable(frame)) {
out_frame = frame;
} else {
out_frame = ff_get_audio_buffer(inlink, nb_samples);
if (!out_frame) {
av_frame_free(&frame);
return AVERROR(ENOMEM);
}
err = av_frame_copy_props(out_frame, frame);
if (err < 0) {
av_frame_free(&out_frame);
av_frame_free(&frame);
return err;
}
}
for (chan = 0; chan < channels; chan++) {
const float *src = (float *)frame->extended_data[chan];
float *dst = (float *)out_frame->extended_data[chan];
ChanParam *cp = &s->channels[chan];
for (i = 0; i < nb_samples; i++) {
update_volume(cp, fabs(src[i]));
dst[i] = av_clipf(src[i] * get_volume(s, cp->volume), -1.0f, 1.0f);
}
}
if (frame != out_frame)
av_frame_free(&frame);
return ff_filter_frame(ctx->outputs[0], out_frame);
}
#define MOD(a, b) (((a) >= (b)) ? (a) - (b) : (a))
static int compand_delay(AVFilterContext *ctx, AVFrame *frame)
{
CompandContext *s = ctx->priv;
AVFilterLink *inlink = ctx->inputs[0];
const int channels = s->nb_channels;
const int nb_samples = frame->nb_samples;
int chan, i, dindex = 0, oindex, count = 0;
AVFrame *out_frame = NULL;
int err;
if (s->pts == AV_NOPTS_VALUE) {
s->pts = (frame->pts == AV_NOPTS_VALUE) ? 0 : frame->pts;
}
for (chan = 0; chan < channels; chan++) {
AVFrame *delay_frame = s->delay_frame;
const float *src = (float *)frame->extended_data[chan];
float *dbuf = (float *)delay_frame->extended_data[chan];
ChanParam *cp = &s->channels[chan];
float *dst;
count = s->delay_count;
dindex = s->delay_index;
for (i = 0, oindex = 0; i < nb_samples; i++) {
const float in = src[i];
update_volume(cp, fabs(in));
if (count >= s->delay_samples) {
if (!out_frame) {
out_frame = ff_get_audio_buffer(inlink, nb_samples - i);
if (!out_frame) {
av_frame_free(&frame);
return AVERROR(ENOMEM);
}
err = av_frame_copy_props(out_frame, frame);
if (err < 0) {
av_frame_free(&out_frame);
av_frame_free(&frame);
return err;
}
out_frame->pts = s->pts;
s->pts += av_rescale_q(nb_samples - i,
(AVRational){ 1, inlink->sample_rate },
inlink->time_base);
}
dst = (float *)out_frame->extended_data[chan];
dst[oindex++] = av_clipf(dbuf[dindex] *
get_volume(s, cp->volume), -1.0f, 1.0f);
} else {
count++;
}
dbuf[dindex] = in;
dindex = MOD(dindex + 1, s->delay_samples);
}
}
s->delay_count = count;
s->delay_index = dindex;
av_frame_free(&frame);
return out_frame ? ff_filter_frame(ctx->outputs[0], out_frame) : 0;
}
static int compand_drain(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
CompandContext *s = ctx->priv;
const int channels = s->nb_channels;
AVFrame *frame = NULL;
int chan, i, dindex;
/* 2048 is to limit output frame size during drain */
frame = ff_get_audio_buffer(outlink, FFMIN(2048, s->delay_count));
if (!frame)
return AVERROR(ENOMEM);
frame->pts = s->pts;
s->pts += av_rescale_q(frame->nb_samples,
(AVRational){ 1, outlink->sample_rate }, outlink->time_base);
for (chan = 0; chan < channels; chan++) {
AVFrame *delay_frame = s->delay_frame;
float *dbuf = (float *)delay_frame->extended_data[chan];
float *dst = (float *)frame->extended_data[chan];
ChanParam *cp = &s->channels[chan];
dindex = s->delay_index;
for (i = 0; i < frame->nb_samples; i++) {
dst[i] = av_clipf(dbuf[dindex] * get_volume(s, cp->volume),
-1.0f, 1.0f);
dindex = MOD(dindex + 1, s->delay_samples);
}
}
s->delay_count -= frame->nb_samples;
s->delay_index = dindex;
return ff_filter_frame(outlink, frame);
}
static int config_output(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
CompandContext *s = ctx->priv;
const int sample_rate = outlink->sample_rate;
double radius = s->curve_dB * M_LN10 / 20.0;
char *p, *saveptr = NULL;
const int channels =
av_get_channel_layout_nb_channels(outlink->channel_layout);
int nb_attacks, nb_decays, nb_points;
int new_nb_items, num;
int i;
int err;
count_items(s->attacks, &nb_attacks);
count_items(s->decays, &nb_decays);
count_items(s->points, &nb_points);
if (channels <= 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid number of channels: %d\n", channels);
return AVERROR(EINVAL);
}
if (nb_attacks > channels || nb_decays > channels) {
av_log(ctx, AV_LOG_ERROR,
"Number of attacks/decays bigger than number of channels.\n");
return AVERROR(EINVAL);
}
uninit(ctx);
s->nb_channels = channels;
s->channels = av_mallocz_array(channels, sizeof(*s->channels));
s->nb_segments = (nb_points + 4) * 2;
s->segments = av_mallocz_array(s->nb_segments, sizeof(*s->segments));
if (!s->channels || !s->segments) {
uninit(ctx);
return AVERROR(ENOMEM);
}
p = s->attacks;
for (i = 0, new_nb_items = 0; i < nb_attacks; i++) {
char *tstr = strtok_r(p, "|", &saveptr);
p = NULL;
new_nb_items += sscanf(tstr, "%f", &s->channels[i].attack) == 1;
if (s->channels[i].attack < 0) {
uninit(ctx);
return AVERROR(EINVAL);
}
}
nb_attacks = new_nb_items;
p = s->decays;
for (i = 0, new_nb_items = 0; i < nb_decays; i++) {
char *tstr = strtok_r(p, "|", &saveptr);
p = NULL;
new_nb_items += sscanf(tstr, "%f", &s->channels[i].decay) == 1;
if (s->channels[i].decay < 0) {
uninit(ctx);
return AVERROR(EINVAL);
}
}
nb_decays = new_nb_items;
if (nb_attacks != nb_decays) {
av_log(ctx, AV_LOG_ERROR,
"Number of attacks %d differs from number of decays %d.\n",
nb_attacks, nb_decays);
uninit(ctx);
return AVERROR(EINVAL);
}
#define S(x) s->segments[2 * ((x) + 1)]
p = s->points;
for (i = 0, new_nb_items = 0; i < nb_points; i++) {
char *tstr = strtok_r(p, "|", &saveptr);
p = NULL;
if (sscanf(tstr, "%f/%f", &S(i).x, &S(i).y) != 2) {
av_log(ctx, AV_LOG_ERROR,
"Invalid and/or missing input/output value.\n");
uninit(ctx);
return AVERROR(EINVAL);
}
if (i && S(i - 1).x > S(i).x) {
av_log(ctx, AV_LOG_ERROR,
"Transfer function input values must be increasing.\n");
uninit(ctx);
return AVERROR(EINVAL);
}
S(i).y -= S(i).x;
av_log(ctx, AV_LOG_DEBUG, "%d: x=%f y=%f\n", i, S(i).x, S(i).y);
new_nb_items++;
}
num = new_nb_items;
/* Add 0,0 if necessary */
if (num == 0 || S(num - 1).x)
num++;
#undef S
#define S(x) s->segments[2 * (x)]
/* Add a tail off segment at the start */
S(0).x = S(1).x - 2 * s->curve_dB;
S(0).y = S(1).y;
num++;
/* Join adjacent colinear segments */
for (i = 2; i < num; i++) {
double g1 = (S(i - 1).y - S(i - 2).y) * (S(i - 0).x - S(i - 1).x);
double g2 = (S(i - 0).y - S(i - 1).y) * (S(i - 1).x - S(i - 2).x);
int j;
/* here we purposefully lose precision so that we can compare floats */
if (fabs(g1 - g2))
continue;
num--;
for (j = --i; j < num; j++)
S(j) = S(j + 1);
}
for (i = 0; !i || s->segments[i - 2].x; i += 2) {
s->segments[i].y += s->gain_dB;
s->segments[i].x *= M_LN10 / 20;
s->segments[i].y *= M_LN10 / 20;
}
#define L(x) s->segments[i - (x)]
for (i = 4; s->segments[i - 2].x; i += 2) {
double x, y, cx, cy, in1, in2, out1, out2, theta, len, r;
L(4).a = 0;
L(4).b = (L(2).y - L(4).y) / (L(2).x - L(4).x);
L(2).a = 0;
L(2).b = (L(0).y - L(2).y) / (L(0).x - L(2).x);
theta = atan2(L(2).y - L(4).y, L(2).x - L(4).x);
len = sqrt(pow(L(2).x - L(4).x, 2.) + pow(L(2).y - L(4).y, 2.));
r = FFMIN(radius, len);
L(3).x = L(2).x - r * cos(theta);
L(3).y = L(2).y - r * sin(theta);
theta = atan2(L(0).y - L(2).y, L(0).x - L(2).x);
len = sqrt(pow(L(0).x - L(2).x, 2.) + pow(L(0).y - L(2).y, 2.));
r = FFMIN(radius, len / 2);
x = L(2).x + r * cos(theta);
y = L(2).y + r * sin(theta);
cx = (L(3).x + L(2).x + x) / 3;
cy = (L(3).y + L(2).y + y) / 3;
L(2).x = x;
L(2).y = y;
in1 = cx - L(3).x;
out1 = cy - L(3).y;
in2 = L(2).x - L(3).x;
out2 = L(2).y - L(3).y;
L(3).a = (out2 / in2 - out1 / in1) / (in2 - in1);
L(3).b = out1 / in1 - L(3).a * in1;
}
L(3).x = 0;
L(3).y = L(2).y;
s->in_min_lin = exp(s->segments[1].x);
s->out_min_lin = exp(s->segments[1].y);
for (i = 0; i < channels; i++) {
ChanParam *cp = &s->channels[i];
if (cp->attack > 1.0 / sample_rate)
cp->attack = 1.0 - exp(-1.0 / (sample_rate * cp->attack));
else
cp->attack = 1.0;
if (cp->decay > 1.0 / sample_rate)
cp->decay = 1.0 - exp(-1.0 / (sample_rate * cp->decay));
else
cp->decay = 1.0;
cp->volume = pow(10.0, s->initial_volume / 20);
}
s->delay_samples = s->delay * sample_rate;
if (s->delay_samples <= 0) {
s->compand = compand_nodelay;
return 0;
}
s->delay_frame = av_frame_alloc();
if (!s->delay_frame) {
uninit(ctx);
return AVERROR(ENOMEM);
}
s->delay_frame->format = outlink->format;
s->delay_frame->nb_samples = s->delay_samples;
s->delay_frame->channel_layout = outlink->channel_layout;
err = av_frame_get_buffer(s->delay_frame, 32);
if (err)
return err;
s->compand = compand_delay;
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
{
AVFilterContext *ctx = inlink->dst;
CompandContext *s = ctx->priv;
return s->compand(ctx, frame);
}
static int request_frame(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
CompandContext *s = ctx->priv;
int ret;
ret = ff_request_frame(ctx->inputs[0]);
if (ret == AVERROR_EOF && s->delay_count)
ret = compand_drain(outlink);
return ret;
}
static const AVFilterPad compand_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.filter_frame = filter_frame,
},
{ NULL }
};
static const AVFilterPad compand_outputs[] = {
{
.name = "default",
.request_frame = request_frame,
.config_props = config_output,
.type = AVMEDIA_TYPE_AUDIO,
},
{ NULL }
};
AVFilter ff_af_compand = {
.name = "compand",
.description = NULL_IF_CONFIG_SMALL(
"Compress or expand audio dynamic range."),
.query_formats = query_formats,
.priv_size = sizeof(CompandContext),
.priv_class = &compand_class,
.init = init,
.uninit = uninit,
.inputs = compand_inputs,
.outputs = compand_outputs,
};

1
libavfilter/allfilters.c
View File

@ -54,6 +54,7 @@ void avfilter_register_all(void)
REGISTER_FILTER(ATRIM, atrim, af);
REGISTER_FILTER(CHANNELMAP, channelmap, af);
REGISTER_FILTER(CHANNELSPLIT, channelsplit, af);
REGISTER_FILTER(COMPAND, compand, af);
REGISTER_FILTER(JOIN, join, af);
REGISTER_FILTER(RESAMPLE, resample, af);
REGISTER_FILTER(VOLUME, volume, af);

4
libavfilter/version.h
View File

@ -30,8 +30,8 @@
#include "libavutil/version.h"
#define LIBAVFILTER_VERSION_MAJOR 4
#define LIBAVFILTER_VERSION_MINOR 1
#define LIBAVFILTER_VERSION_MICRO 1
#define LIBAVFILTER_VERSION_MINOR 2
#define LIBAVFILTER_VERSION_MICRO 0
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
LIBAVFILTER_VERSION_MINOR, \