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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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Modernizing the documentation, making it simpler to read an modify and allowing us to possibly switch to hotdoc in the future.
448 lines
11 KiB
C
448 lines
11 KiB
C
/* GStreamer
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* Copyright (C) <2014> Wim Taymans <wim.taymans@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <string.h>
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#include <stdio.h>
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#include <math.h>
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#include "video-resampler.h"
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#ifndef GST_DISABLE_GST_DEBUG
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#define GST_CAT_DEFAULT ensure_debug_category()
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static GstDebugCategory *
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ensure_debug_category (void)
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{
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static gsize cat_gonce = 0;
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if (g_once_init_enter (&cat_gonce)) {
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gsize cat_done;
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cat_done = (gsize) _gst_debug_category_new ("video-resampler", 0,
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"video-resampler object");
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g_once_init_leave (&cat_gonce, cat_done);
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}
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return (GstDebugCategory *) cat_gonce;
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}
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#else
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#define ensure_debug_category() /* NOOP */
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#endif /* GST_DISABLE_GST_DEBUG */
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/**
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* SECTION:gstvideoresampler
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* @title: GstVideoResampler
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* @short_description: Utility structure for resampler information
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*
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* #GstVideoResampler is a structure which holds the information
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* required to perform various kinds of resampling filtering.
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*
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*/
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#define DEFAULT_OPT_CUBIC_B (1.0 / 3.0)
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#define DEFAULT_OPT_CUBIC_C (1.0 / 3.0)
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#define DEFAULT_OPT_ENVELOPE 2.0
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#define DEFAULT_OPT_SHARPNESS 1.0
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#define DEFAULT_OPT_SHARPEN 0.0
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#define DEFAULT_OPT_MAX_TAPS 128
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typedef struct _ResamplerParams ResamplerParams;
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struct _ResamplerParams
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{
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GstVideoResamplerMethod method;
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GstVideoResamplerFlags flags;
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gdouble shift;
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gdouble (*get_tap) (ResamplerParams * params, gint l, gint xi, gdouble x);
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/* for cubic */
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gdouble b, c;
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/* used by lanczos */
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gdouble ex, fx, dx;
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/* extra params */
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gdouble envelope;
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gdouble sharpness;
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gdouble sharpen;
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GstVideoResampler *resampler;
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};
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static gdouble
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get_opt_double (GstStructure * options, const gchar * name, gdouble def)
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{
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gdouble res;
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if (!options || !gst_structure_get_double (options, name, &res))
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res = def;
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return res;
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}
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static gint
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get_opt_int (GstStructure * options, const gchar * name, gint def)
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{
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gint res;
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if (!options || !gst_structure_get_int (options, name, &res))
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res = def;
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return res;
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}
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#define GET_OPT_CUBIC_B(options) get_opt_double(options, \
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GST_VIDEO_RESAMPLER_OPT_CUBIC_B, DEFAULT_OPT_CUBIC_B)
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#define GET_OPT_CUBIC_C(options) get_opt_double(options, \
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GST_VIDEO_RESAMPLER_OPT_CUBIC_C, DEFAULT_OPT_CUBIC_C)
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#define GET_OPT_ENVELOPE(options) get_opt_double(options, \
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GST_VIDEO_RESAMPLER_OPT_ENVELOPE, DEFAULT_OPT_ENVELOPE)
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#define GET_OPT_SHARPNESS(options) get_opt_double(options, \
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GST_VIDEO_RESAMPLER_OPT_SHARPNESS, DEFAULT_OPT_SHARPNESS)
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#define GET_OPT_SHARPEN(options) get_opt_double(options, \
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GST_VIDEO_RESAMPLER_OPT_SHARPEN, DEFAULT_OPT_SHARPEN)
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#define GET_OPT_MAX_TAPS(options) get_opt_int(options, \
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GST_VIDEO_RESAMPLER_OPT_MAX_TAPS, DEFAULT_OPT_MAX_TAPS)
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static double
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sinc (double x)
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{
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if (x == 0)
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return 1;
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return sin (G_PI * x) / (G_PI * x);
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}
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static double
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envelope (double x)
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{
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if (x <= -1 || x >= 1)
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return 0;
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return sinc (x);
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}
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static gdouble
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get_nearest_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
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{
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return 1.0;
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}
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static gdouble
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get_linear_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
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{
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gdouble res, a;
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gint xl = xi + l;
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a = fabs (x - xl) * params->fx;
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if (a < 1.0)
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res = 1.0 - a;
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else
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res = 0.0;
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return res;
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}
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static gdouble
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get_cubic_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
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{
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gdouble a, a2, a3, b, c;
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gint xl = xi + l;
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a = fabs (x - xl) * params->fx;
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a2 = a * a;
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a3 = a2 * a;
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b = params->b;
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c = params->c;
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if (a <= 1.0)
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return ((12.0 - 9.0 * b - 6.0 * c) * a3 +
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(-18.0 + 12.0 * b + 6.0 * c) * a2 + (6.0 - 2.0 * b)) / 6.0;
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else if (a <= 2.0)
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return ((-b - 6.0 * c) * a3 +
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(6.0 * b + 30.0 * c) * a2 +
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(-12.0 * b - 48.0 * c) * a + (8.0 * b + 24.0 * c)) / 6.0;
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else
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return 0.0;
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}
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static gdouble
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get_sinc_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
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{
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gint xl = xi + l;
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return sinc ((x - xl) * params->fx);
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}
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static gdouble
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get_lanczos_tap (ResamplerParams * params, gint l, gint xi, gdouble x)
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{
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gint xl = xi + l;
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gdouble env = envelope ((x - xl) * params->ex);
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return (sinc ((x - xl) * params->fx) - params->sharpen) * env;
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}
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static void
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resampler_calculate_taps (ResamplerParams * params)
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{
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GstVideoResampler *resampler = params->resampler;
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gint j;
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guint32 *offset, *n_taps, *phase;
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gint tap_offs;
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gint max_taps;
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gint in_size, out_size;
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gdouble shift;
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gdouble corr;
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in_size = resampler->in_size;
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out_size = resampler->out_size;
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max_taps = resampler->max_taps;
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tap_offs = (max_taps - 1) / 2;
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corr = (max_taps == 1 ? 0.0 : 0.5);
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shift = params->shift;
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resampler->taps = g_malloc (sizeof (gdouble) * max_taps * out_size);
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n_taps = resampler->n_taps = g_malloc (sizeof (guint32) * out_size);
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offset = resampler->offset = g_malloc (sizeof (guint32) * out_size);
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phase = resampler->phase = g_malloc (sizeof (guint32) * out_size);
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for (j = 0; j < out_size; j++) {
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gdouble ox, x;
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gint xi;
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gint l;
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gdouble weight;
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gdouble *taps;
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/* center of the output pixel */
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ox = (0.5 + (gdouble) j - shift) / out_size;
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/* x is the source pixel to use, can be fractional */
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x = ox * (gdouble) in_size - corr;
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x = CLAMP (x, 0, in_size - 1);
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/* this is the first source pixel to use */
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xi = floor (x - tap_offs);
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offset[j] = xi;
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phase[j] = j;
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n_taps[j] = max_taps;
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weight = 0;
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taps = resampler->taps + j * max_taps;
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for (l = 0; l < max_taps; l++) {
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taps[l] = params->get_tap (params, l, xi, x);
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weight += taps[l];
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}
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for (l = 0; l < max_taps; l++)
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taps[l] /= weight;
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if (xi < 0) {
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gint sh = -xi;
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for (l = 0; l < sh; l++) {
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taps[sh] += taps[l];
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}
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for (l = 0; l < max_taps - sh; l++) {
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taps[l] = taps[sh + l];
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}
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for (; l < max_taps; l++) {
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taps[l] = 0;
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}
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offset[j] += sh;
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}
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if (xi > in_size - max_taps) {
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gint sh = xi - (in_size - max_taps);
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for (l = 0; l < sh; l++) {
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taps[max_taps - sh - 1] += taps[max_taps - sh + l];
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}
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for (l = 0; l < max_taps - sh; l++) {
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taps[max_taps - 1 - l] = taps[max_taps - 1 - sh - l];
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}
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for (l = 0; l < sh; l++) {
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taps[l] = 0;
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}
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offset[j] -= sh;
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}
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}
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}
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static void
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resampler_dump (GstVideoResampler * resampler)
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{
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#if 0
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gint i, max_taps, out_size;
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out_size = resampler->out_size;
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max_taps = resampler->max_taps;
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for (i = 0; i < out_size; i++) {
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gint j, o, phase, n_taps;
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gdouble sum;
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o = resampler->offset[i];
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n_taps = resampler->n_taps[i];
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phase = resampler->phase[i];
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printf ("%u: \t%d ", i, o);
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sum = 0;
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for (j = 0; j < n_taps; j++) {
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gdouble tap;
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tap = resampler->taps[phase * max_taps + j];
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printf ("\t%f ", tap);
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sum += tap;
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}
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printf ("\t: sum %f\n", sum);
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}
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#endif
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}
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/**
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* gst_video_resampler_new:
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* @resampler: a #GstVideoResampler
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* @method: a #GstVideoResamplerMethod
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* @flags: #GstVideoResamplerFlags
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* @n_phases: number of phases to use
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* @n_taps: number of taps to use
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* @in_size: number of source elements
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* @out_size: number of destination elements
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* @options: extra options
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*
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* Make a new resampler. @in_size source elements will
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* be resampled to @out_size destination elements.
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*
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* @n_taps specifies the amount of elements to use from the source for one output
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* element. If n_taps is 0, this function chooses a good value automatically based
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* on the @method and @in_size/@out_size.
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*
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* Returns: %TRUE on success
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*
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* Since: 1.6
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*/
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gboolean
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gst_video_resampler_init (GstVideoResampler * resampler,
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GstVideoResamplerMethod method, GstVideoResamplerFlags flags,
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guint n_phases, guint n_taps, gdouble shift, guint in_size, guint out_size,
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GstStructure * options)
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{
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ResamplerParams params;
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gint max_taps;
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gdouble scale_factor;
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g_return_val_if_fail (in_size != 0, FALSE);
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g_return_val_if_fail (out_size != 0, FALSE);
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g_return_val_if_fail (n_phases == out_size, FALSE);
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resampler->in_size = in_size;
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resampler->out_size = out_size;
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resampler->n_phases = n_phases;
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params.method = method;
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params.flags = flags;
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params.shift = shift;
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params.resampler = resampler;
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GST_DEBUG ("%d %u %u->%u", method, n_taps, in_size, out_size);
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params.sharpness = GET_OPT_SHARPNESS (options);
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params.sharpen = GET_OPT_SHARPEN (options);
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scale_factor = in_size / (gdouble) out_size;
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if (scale_factor > 1.0) {
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params.fx = (1.0 / scale_factor) * params.sharpness;
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} else {
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params.fx = (1.0) * params.sharpness;
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}
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max_taps = GET_OPT_MAX_TAPS (options);
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n_taps = MIN (n_taps, max_taps);
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switch (method) {
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case GST_VIDEO_RESAMPLER_METHOD_NEAREST:
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params.envelope = GET_OPT_ENVELOPE (options);
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params.get_tap = get_nearest_tap;
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if (n_taps == 0)
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n_taps = 1;
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break;
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case GST_VIDEO_RESAMPLER_METHOD_LINEAR:
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params.get_tap = get_linear_tap;
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params.envelope = 1.0;
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break;
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case GST_VIDEO_RESAMPLER_METHOD_CUBIC:
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params.b = GET_OPT_CUBIC_B (options);
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params.c = GET_OPT_CUBIC_C (options);
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params.envelope = 2.0;
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params.get_tap = get_cubic_tap;
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break;
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case GST_VIDEO_RESAMPLER_METHOD_SINC:
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params.envelope = GET_OPT_ENVELOPE (options);
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params.get_tap = get_sinc_tap;
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break;
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case GST_VIDEO_RESAMPLER_METHOD_LANCZOS:
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params.envelope = GET_OPT_ENVELOPE (options);
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params.get_tap = get_lanczos_tap;
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break;
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default:
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break;
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}
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if (n_taps == 0) {
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params.dx = ceil (2.0 * params.envelope / params.fx);
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n_taps = CLAMP (params.dx, 0, max_taps);
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}
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if (flags & GST_VIDEO_RESAMPLER_FLAG_HALF_TAPS && n_taps > 3)
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n_taps /= 2;
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params.fx = 2.0 * params.envelope / n_taps;
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params.ex = 2.0 / n_taps;
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if (n_taps > in_size)
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n_taps = in_size;
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resampler->max_taps = n_taps;
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resampler_calculate_taps (¶ms);
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resampler_dump (resampler);
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return TRUE;
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}
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/**
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* gst_video_resampler_clear:
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* @resampler: a #GstVideoResampler
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*
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* Clear a previously initialized #GstVideoResampler @resampler.
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*
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* Since: 1.6
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*/
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void
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gst_video_resampler_clear (GstVideoResampler * resampler)
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{
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g_return_if_fail (resampler != NULL);
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g_free (resampler->phase);
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g_free (resampler->offset);
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g_free (resampler->n_taps);
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g_free (resampler->taps);
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}
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