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FFmpeg/libavfilter/vf_curves.c
Clément Bœsch 65fc80f012 lavfi: add curves filter.
2013-03-10 03:00:10 +01:00

364 lines
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/*
* Copyright (c) 2013 Clément Bœsch
*
* 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 "libavutil/eval.h"
#include "libavutil/avassert.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"
struct keypoint {
double x, y;
struct keypoint *next;
};
#define NB_COMP 3
typedef struct {
const AVClass *class;
char *comp_points_str[NB_COMP];
uint8_t graph[NB_COMP][256];
} CurvesContext;
#define OFFSET(x) offsetof(CurvesContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
static const AVOption curves_options[] = {
{ "red", "set red points coordinates", OFFSET(comp_points_str[0]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ "r", "set red points coordinates", OFFSET(comp_points_str[0]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ "green", "set green points coordinates", OFFSET(comp_points_str[1]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ "g", "set green points coordinates", OFFSET(comp_points_str[1]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ "blue", "set blue points coordinates", OFFSET(comp_points_str[2]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ "b", "set blue points coordinates", OFFSET(comp_points_str[2]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(curves);
static struct keypoint *make_point(double x, double y, struct keypoint *next)
{
struct keypoint *point = av_mallocz(sizeof(*point));
if (!point)
return NULL;
point->x = x;
point->y = y;
point->next = next;
return point;
}
static int parse_points_str(AVFilterContext *ctx, struct keypoint **points, const char *s)
{
char *p = (char *)s; // strtod won't alter the string
struct keypoint *last = NULL;
/* construct a linked list based on the key points string */
while (p && *p) {
struct keypoint *point = make_point(0, 0, NULL);
if (!point)
return AVERROR(ENOMEM);
point->x = av_strtod(p, &p); if (p && *p) p++;
point->y = av_strtod(p, &p); if (p && *p) p++;
if (point->x < 0 || point->x > 1 || point->y < 0 || point->y > 1) {
av_log(ctx, AV_LOG_ERROR, "Invalid key point coordinates (%f;%f), "
"x and y must be in the [0;1] range.\n", point->x, point->y);
return AVERROR(EINVAL);
}
if (!*points)
*points = point;
if (last) {
if ((int)(last->x * 255) >= (int)(point->x * 255)) {
av_log(ctx, AV_LOG_ERROR, "Key point coordinates (%f;%f) "
"and (%f;%f) are too close from each other or not "
"strictly increasing on the x-axis\n",
last->x, last->y, point->x, point->y);
return AVERROR(EINVAL);
}
last->next = point;
}
last = point;
}
/* auto insert first key point if missing at x=0 */
if (!*points) {
last = make_point(0, 0, NULL);
if (!last)
return AVERROR(ENOMEM);
last->x = last->y = 0;
*points = last;
} else if ((*points)->x != 0.) {
struct keypoint *newfirst = make_point(0, 0, *points);
if (!newfirst)
return AVERROR(ENOMEM);
*points = newfirst;
}
av_assert0(last);
/* auto insert last key point if missing at x=1 */
if (last->x != 1.) {
struct keypoint *point = make_point(1, 1, NULL);
if (!point)
return AVERROR(ENOMEM);
last->next = point;
}
return 0;
}
static int get_nb_points(const struct keypoint *d)
{
int n = 0;
while (d) {
n++;
d = d->next;
}
return n;
}
/**
* Natural cubic spline interpolation
* Finding curves using Cubic Splines notes by Steven Rauch and John Stockie.
* @see http://people.math.sfu.ca/~stockie/teaching/macm316/notes/splines.pdf
*/
static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *points)
{
int i, ret = 0;
const struct keypoint *point;
double xprev = 0;
int n = get_nb_points(points); // number of splines
double (*matrix)[3] = av_calloc(n, sizeof(*matrix));
double *h = av_malloc((n - 1) * sizeof(*h));
double *r = av_calloc(n, sizeof(*r));
if (!matrix || !h || !r) {
ret = AVERROR(ENOMEM);
goto end;
}
/* h(i) = x(i+1) - x(i) */
i = -1;
for (point = points; point; point = point->next) {
if (i != -1)
h[i] = point->x - xprev;
xprev = point->x;
i++;
}
/* right-side of the polynomials, will be modified to contains the solution */
point = points;
for (i = 1; i < n - 1; i++) {
double yp = point->y,
yc = point->next->y,
yn = point->next->next->y;
r[i] = 6 * ((yn-yc)/h[i] - (yc-yp)/h[i-1]);
point = point->next;
}
#define B 0 /* sub diagonal (below main) */
#define M 1 /* main diagonal (center) */
#define A 2 /* sup diagonal (above main) */
/* left side of the polynomials into a tridiagonal matrix. */
matrix[0][M] = matrix[n - 1][M] = 1;
for (i = 1; i < n - 1; i++) {
matrix[i][B] = h[i-1];
matrix[i][M] = 2 * (h[i-1] + h[i]);
matrix[i][A] = h[i];
}
/* tridiagonal solving of the linear system */
for (i = 1; i < n; i++) {
double den = matrix[i][M] - matrix[i][B] * matrix[i-1][A];
double k = den ? 1./den : 1.;
matrix[i][A] *= k;
r[i] = (r[i] - matrix[i][B] * r[i - 1]) * k;
}
for (i = n - 2; i >= 0; i--)
r[i] = r[i] - matrix[i][A] * r[i + 1];
/* compute the graph with x=[0..255] */
i = 0;
point = points;
av_assert0(point->next); // always at least 2 key points
while (point->next) {
double yc = point->y;
double yn = point->next->y;
double a = yc;
double b = (yn-yc)/h[i] - h[i]*r[i]/2. - h[i]*(r[i+1]-r[i])/6.;
double c = r[i] / 2.;
double d = (r[i+1] - r[i]) / (6.*h[i]);
int x;
int x_start = point->x * 255;
int x_end = point->next->x * 255;
av_assert0(x_start >= 0 && x_start <= 255 &&
x_end >= 0 && x_end <= 255);
for (x = x_start; x <= x_end; x++) {
double xx = (x - x_start) * 1/255.;
double yy = a + b*xx + c*xx*xx + d*xx*xx*xx;
y[x] = av_clipf(yy, 0, 1) * 255;
av_log(ctx, AV_LOG_DEBUG, "f(%f)=%f -> y[%d]=%d\n", xx, yy, x, y[x]);
}
point = point->next;
i++;
}
end:
av_free(matrix);
av_free(h);
av_free(r);
return ret;
}
static av_cold int init(AVFilterContext *ctx, const char *args)
{
int i, j, ret;
CurvesContext *curves = ctx->priv;
struct keypoint *comp_points[NB_COMP] = {0};
curves->class = &curves_class;
av_opt_set_defaults(curves);
if ((ret = av_set_options_string(curves, args, "=", ":")) < 0)
return ret;
for (i = 0; i < NB_COMP; i++) {
ret = parse_points_str(ctx, comp_points + i, curves->comp_points_str[i]);
if (ret < 0)
return ret;
ret = interpolate(ctx, curves->graph[i], comp_points[i]);
if (ret < 0)
return ret;
}
if (av_log_get_level() >= AV_LOG_VERBOSE) {
for (i = 0; i < NB_COMP; i++) {
struct keypoint *point = comp_points[i];
av_log(ctx, AV_LOG_VERBOSE, "#%d points:", i);
while (point) {
av_log(ctx, AV_LOG_VERBOSE, " (%f;%f)", point->x, point->y);
point = point->next;
}
av_log(ctx, AV_LOG_VERBOSE, "\n");
av_log(ctx, AV_LOG_VERBOSE, "#%d values:", i);
for (j = 0; j < 256; j++)
av_log(ctx, AV_LOG_VERBOSE, " %02X", curves->graph[i][j]);
av_log(ctx, AV_LOG_VERBOSE, "\n");
}
}
for (i = 0; i < NB_COMP; i++) {
struct keypoint *point = comp_points[i];
while (point) {
struct keypoint *next = point->next;
av_free(point);
point = next;
}
}
av_opt_free(curves);
return 0;
}
static int query_formats(AVFilterContext *ctx)
{
static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_RGB24, AV_PIX_FMT_NONE};
ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
int x, y, i, direct = 0;
AVFilterContext *ctx = inlink->dst;
CurvesContext *curves = ctx->priv;
AVFilterLink *outlink = inlink->dst->outputs[0];
AVFrame *out;
uint8_t *dst;
const uint8_t *src;
if (av_frame_is_writable(in)) {
direct = 1;
out = in;
} else {
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out) {
av_frame_free(&in);
return AVERROR(ENOMEM);
}
av_frame_copy_props(out, in);
}
dst = out->data[0];
src = in ->data[0];
for (y = 0; y < inlink->h; y++) {
uint8_t *dstp = dst;
const uint8_t *srcp = src;
for (x = 0; x < inlink->w; x++)
for (i = 0; i < NB_COMP; i++, dstp++, srcp++)
*dstp = curves->graph[i][*srcp];
dst += out->linesize[0];
src += in ->linesize[0];
}
if (!direct)
av_frame_free(&in);
return ff_filter_frame(outlink, out);
}
static const AVFilterPad curves_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
{ NULL }
};
static const AVFilterPad curves_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
},
{ NULL }
};
AVFilter avfilter_vf_curves = {
.name = "curves",
.description = NULL_IF_CONFIG_SMALL("Adjust components curves."),
.priv_size = sizeof(CurvesContext),
.init = init,
.query_formats = query_formats,
.inputs = curves_inputs,
.outputs = curves_outputs,
.priv_class = &curves_class,
};
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