gstreamer/gst-libs/gst/video/video-resampler.c

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/* GStreamer
* Copyright (C) <2014> Wim Taymans <wim.taymans@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include <stdio.h>
#include <math.h>
#include "video-resampler.h"
#define DEFAULT_OPT_CUBIC_B (1.0 / 3.0)
#define DEFAULT_OPT_CUBIC_C (1.0 / 3.0)
#define DEFAULT_OPT_ENVELOPE 2.0
#define DEFAULT_OPT_SHARPNESS 1.0
#define DEFAULT_OPT_SHARPEN 0.0
#define DEFAULT_OPT_MAX_TAPS 128
typedef struct _ResamplerParams ResamplerParams;
struct _ResamplerParams
{
GstVideoResamplerMethod method;
GstVideoResamplerFlags flags;
gdouble shift;
gdouble (*get_tap) (ResamplerParams * params, gint l, gint xi, gdouble x);
/* for cubic */
gdouble b, c;
/* used by lanczos */
gdouble ex, fx, dx;
/* extra params */
gdouble envelope;
gdouble sharpness;
gdouble sharpen;
GstVideoResampler *resampler;
};
static gdouble
get_opt_double (GstStructure * options, const gchar * name, gdouble def)
{
gdouble res;
if (!options || !gst_structure_get_double (options, name, &res))
res = def;
return res;
}
static gint
get_opt_int (GstStructure * options, const gchar * name, gint def)
{
gint res;
if (!options || !gst_structure_get_int (options, name, &res))
res = def;
return res;
}
#define GET_OPT_CUBIC_B(options) get_opt_double(options, \
GST_VIDEO_RESAMPLER_OPT_CUBIC_B, DEFAULT_OPT_CUBIC_B)
#define GET_OPT_CUBIC_C(options) get_opt_double(options, \
GST_VIDEO_RESAMPLER_OPT_CUBIC_C, DEFAULT_OPT_CUBIC_C)
#define GET_OPT_ENVELOPE(options) get_opt_double(options, \
GST_VIDEO_RESAMPLER_OPT_ENVELOPE, DEFAULT_OPT_ENVELOPE)
#define GET_OPT_SHARPNESS(options) get_opt_double(options, \
GST_VIDEO_RESAMPLER_OPT_SHARPNESS, DEFAULT_OPT_SHARPNESS)
#define GET_OPT_SHARPEN(options) get_opt_double(options, \
GST_VIDEO_RESAMPLER_OPT_SHARPEN, DEFAULT_OPT_SHARPEN)
#define GET_OPT_MAX_TAPS(options) get_opt_int(options, \
GST_VIDEO_RESAMPLER_OPT_MAX_TAPS, DEFAULT_OPT_MAX_TAPS)
static double
sinc (double x)
{
if (x == 0)
return 1;
return sin (G_PI * x) / (G_PI * x);
}
static double
envelope (double x)
{
if (x <= -1 || x >= 1)
return 0;
return sinc (x);
}
static gdouble
get_nearest_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
return 1.0;
}
static gdouble
get_linear_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gdouble res, a;
gint xl = xi + l;
a = fabs (x - xl) * params->fx;
if (a < 1.0)
res = 1.0 - a;
else
res = 0.0;
return res;
}
static gdouble
get_cubic_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gdouble a, a2, a3, b, c;
gint xl = xi + l;
a = fabs (x - xl) * params->fx;
a2 = a * a;
a3 = a2 * a;
b = params->b;
c = params->c;
if (a <= 1.0)
return ((12.0 - 9.0 * b - 6.0 * c) * a3 +
(-18.0 + 12.0 * b + 6.0 * c) * a2 + (6.0 - 2.0 * b)) / 6.0;
else if (a <= 2.0)
return ((-b - 6.0 * c) * a3 +
(6.0 * b + 30.0 * c) * a2 +
(-12.0 * b - 48.0 * c) * a + (8.0 * b + 24.0 * c)) / 6.0;
else
return 0.0;
}
static gdouble
get_sinc_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gint xl = xi + l;
return sinc ((x - xl) * params->fx);
}
static gdouble
get_lanczos_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
{
gint xl = xi + l;
gdouble env = envelope ((x - xl) * params->ex);
return (sinc ((x - xl) * params->fx) - params->sharpen) * env;
}
static void
resampler_calculate_taps (ResamplerParams * params)
{
GstVideoResampler *resampler = params->resampler;
gint j;
guint32 *offset, *n_taps, *phase;
gint tap_offs;
gint max_taps;
gint in_size, out_size;
gdouble shift;
gdouble corr;
in_size = resampler->in_size;
out_size = resampler->out_size;
max_taps = resampler->max_taps;
tap_offs = (max_taps - 1) / 2;
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corr = (max_taps == 1 ? 0.0 : 0.5);
shift = params->shift;
resampler->taps = g_malloc (sizeof (gdouble) * max_taps * out_size);
n_taps = resampler->n_taps = g_malloc (sizeof (guint32) * out_size);
offset = resampler->offset = g_malloc (sizeof (guint32) * out_size);
phase = resampler->phase = g_malloc (sizeof (guint32) * out_size);
for (j = 0; j < out_size; j++) {
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gdouble ox, x;
gint xi;
gint l;
gdouble weight;
gdouble *taps;
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/* center of the output pixel */
ox = (0.5 + (gdouble) j - shift) / out_size;
/* x is the source pixel to use, can be fractional */
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x = ox * (gdouble) in_size - corr;
x = CLAMP (x, 0, in_size - 1);
/* this is the first source pixel to use */
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xi = floor (x - tap_offs);
offset[j] = xi;
phase[j] = j;
n_taps[j] = max_taps;
weight = 0;
taps = resampler->taps + j * max_taps;
for (l = 0; l < max_taps; l++) {
taps[l] = params->get_tap (params, l, xi, x);
weight += taps[l];
}
for (l = 0; l < max_taps; l++)
taps[l] /= weight;
if (xi < 0) {
gint sh = -xi;
for (l = 0; l < sh; l++) {
taps[sh] += taps[l];
}
for (l = 0; l < max_taps - sh; l++) {
taps[l] = taps[sh + l];
}
for (; l < max_taps; l++) {
taps[l] = 0;
}
offset[j] += sh;
}
if (xi > in_size - max_taps) {
gint sh = xi - (in_size - max_taps);
for (l = 0; l < sh; l++) {
taps[max_taps - sh - 1] += taps[max_taps - sh + l];
}
for (l = 0; l < max_taps - sh; l++) {
taps[max_taps - 1 - l] = taps[max_taps - 1 - sh - l];
}
for (l = 0; l < sh; l++) {
taps[l] = 0;
}
offset[j] -= sh;
}
}
}
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static void
resampler_dump (GstVideoResampler * resampler)
{
#if 0
gint i, max_taps, out_size;
out_size = resampler->out_size;
max_taps = resampler->max_taps;
for (i = 0; i < out_size; i++) {
gint j, o, phase, n_taps;
gdouble sum;
o = resampler->offset[i];
n_taps = resampler->n_taps[i];
phase = resampler->phase[i];
printf ("%u: \t%d ", i, o);
sum = 0;
for (j = 0; j < n_taps; j++) {
gdouble tap;
tap = resampler->taps[phase * max_taps + j];
printf ("\t%f ", tap);
sum += tap;
}
printf ("\t: sum %f\n", sum);
}
#endif
}
/**
* gst_video_resampler_new:
* @resampler: a #GstVideoResampler
* @method: a #GstVideoResamplerMethod
* @flags: #GstVideoResamplerFlags
* @n_phases: number of phases to use
* @n_taps: number of taps to use
* @in_size: number of source elements
* @out_size: number of destination elements
* @options: extra options
*
* Make a new resampler. @in_size source elements will
* be resampled to @out_size destination elements.
*
* @n_taps specifies the amount of elements to use from the source for one output
* element. If n_taps is 0, this function chooses a good value automatically based
* on the @method and @in_size/@out_size.
*
* Returns: %TRUE on success
*
* Since: 1.6
*/
gboolean
gst_video_resampler_init (GstVideoResampler * resampler,
GstVideoResamplerMethod method, GstVideoResamplerFlags flags,
guint n_phases, guint n_taps, gdouble shift, guint in_size, guint out_size,
GstStructure * options)
{
ResamplerParams params;
gint max_taps;
gdouble scale_factor;
g_return_val_if_fail (in_size != 0, FALSE);
g_return_val_if_fail (out_size != 0, FALSE);
g_return_val_if_fail (n_phases == out_size, FALSE);
resampler->in_size = in_size;
resampler->out_size = out_size;
resampler->n_phases = n_phases;
params.method = method;
params.flags = flags;
params.shift = shift;
params.resampler = resampler;
GST_DEBUG ("%d %u %u->%u", method, n_taps, in_size, out_size);
params.sharpness = GET_OPT_SHARPNESS (options);
params.sharpen = GET_OPT_SHARPEN (options);
scale_factor = in_size / (gdouble) out_size;
if (scale_factor > 1.0) {
params.fx = (1.0 / scale_factor) * params.sharpness;
} else {
params.fx = (1.0) * params.sharpness;
}
max_taps = GET_OPT_MAX_TAPS (options);
n_taps = MIN (n_taps, max_taps);
switch (method) {
case GST_VIDEO_RESAMPLER_METHOD_NEAREST:
params.get_tap = get_nearest_tap;
if (n_taps == 0)
n_taps = 1;
break;
case GST_VIDEO_RESAMPLER_METHOD_LINEAR:
params.get_tap = get_linear_tap;
params.envelope = 1.0;
break;
case GST_VIDEO_RESAMPLER_METHOD_CUBIC:
params.b = GET_OPT_CUBIC_B (options);
params.c = GET_OPT_CUBIC_C (options);
params.envelope = 2.0;
params.get_tap = get_cubic_tap;
break;
case GST_VIDEO_RESAMPLER_METHOD_SINC:
params.envelope = GET_OPT_ENVELOPE (options);
params.get_tap = get_sinc_tap;
break;
case GST_VIDEO_RESAMPLER_METHOD_LANCZOS:
params.envelope = GET_OPT_ENVELOPE (options);
params.get_tap = get_lanczos_tap;
break;
default:
break;
}
if (n_taps == 0) {
params.dx = ceil (2.0 * params.envelope / params.fx);
n_taps = CLAMP (params.dx, 0, max_taps);
}
params.fx = 2.0 * params.envelope / n_taps;
params.ex = 2.0 / n_taps;
if (n_taps > in_size)
n_taps = in_size;
resampler->max_taps = n_taps;
resampler_calculate_taps (&params);
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resampler_dump (resampler);
return TRUE;
}
/**
* gst_video_resampler_clear:
* @resampler: a #GstVideoResampler
*
* Clear a previously initialized #GstVideoResampler @resampler.
*
* Since: 1.6
*/
void
gst_video_resampler_clear (GstVideoResampler * resampler)
{
g_return_if_fail (resampler != NULL);
g_free (resampler->phase);
g_free (resampler->offset);
g_free (resampler->n_taps);
g_free (resampler->taps);
}