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3e6016622e
Both of these dithering methods are from http://pippin.gimp.org/a_dither/ for GIF they can be considered better than bayer (provides more gray-levels), and spatial stability - often more than twice as good compression and less visual flicker than error diffusion methods (the methods also avoids error-shadow artifacts of diffusion dithers). These methods are similar to blue/green noise type dither masks; but are simple enough to generate their mask on the fly. They are still research work in progress; though more expensive to generate masks (which can be used in a LUT) like 'void and cluster' and similar methods will yield superior results
94 lines
7.8 KiB
C
94 lines
7.8 KiB
C
/*
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* Copyright (C) 2001-2003 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/avutil.h"
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#include "libavutil/opt.h"
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#include "libavutil/pixfmt.h"
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#include "swscale.h"
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#include "swscale_internal.h"
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static const char *sws_context_to_name(void *ptr)
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{
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return "swscaler";
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}
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#define OFFSET(x) offsetof(SwsContext, x)
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#define DEFAULT 0
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#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption swscale_options[] = {
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{ "sws_flags", "scaler flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, { .i64 = SWS_BICUBIC }, 0, UINT_MAX, VE, "sws_flags" },
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{ "fast_bilinear", "fast bilinear", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_FAST_BILINEAR }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "bilinear", "bilinear", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BILINEAR }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "bicubic", "bicubic", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BICUBIC }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "experimental", "experimental", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_X }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "neighbor", "nearest neighbor", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_POINT }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "area", "averaging area", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_AREA }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "bicublin", "luma bicubic, chroma bilinear", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BICUBLIN }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "gauss", "gaussian", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_GAUSS }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "sinc", "sinc", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_SINC }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "lanczos", "lanczos", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_LANCZOS }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "spline", "natural bicubic spline", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_SPLINE }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "print_info", "print info", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_PRINT_INFO }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "accurate_rnd", "accurate rounding", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_ACCURATE_RND }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "full_chroma_int", "full chroma interpolation", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_FULL_CHR_H_INT }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "full_chroma_inp", "full chroma input", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_FULL_CHR_H_INP }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "bitexact", "", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_BITEXACT }, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "error_diffusion", "error diffusion dither", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_ERROR_DIFFUSION}, INT_MIN, INT_MAX, VE, "sws_flags" },
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{ "srcw", "source width", OFFSET(srcW), AV_OPT_TYPE_INT, { .i64 = 16 }, 1, INT_MAX, VE },
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{ "srch", "source height", OFFSET(srcH), AV_OPT_TYPE_INT, { .i64 = 16 }, 1, INT_MAX, VE },
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{ "dstw", "destination width", OFFSET(dstW), AV_OPT_TYPE_INT, { .i64 = 16 }, 1, INT_MAX, VE },
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{ "dsth", "destination height", OFFSET(dstH), AV_OPT_TYPE_INT, { .i64 = 16 }, 1, INT_MAX, VE },
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{ "src_format", "source format", OFFSET(srcFormat), AV_OPT_TYPE_INT, { .i64 = DEFAULT }, 0, AV_PIX_FMT_NB - 1, VE },
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{ "dst_format", "destination format", OFFSET(dstFormat), AV_OPT_TYPE_INT, { .i64 = DEFAULT }, 0, AV_PIX_FMT_NB - 1, VE },
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{ "src_range", "source range", OFFSET(srcRange), AV_OPT_TYPE_INT, { .i64 = DEFAULT }, 0, 1, VE },
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{ "dst_range", "destination range", OFFSET(dstRange), AV_OPT_TYPE_INT, { .i64 = DEFAULT }, 0, 1, VE },
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{ "param0", "scaler param 0", OFFSET(param[0]), AV_OPT_TYPE_DOUBLE, { .dbl = SWS_PARAM_DEFAULT }, INT_MIN, INT_MAX, VE },
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{ "param1", "scaler param 1", OFFSET(param[1]), AV_OPT_TYPE_DOUBLE, { .dbl = SWS_PARAM_DEFAULT }, INT_MIN, INT_MAX, VE },
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{ "src_v_chr_pos", "source vertical chroma position in luma grid/256" , OFFSET(src_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 512, VE },
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{ "src_h_chr_pos", "source horizontal chroma position in luma grid/256", OFFSET(src_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 512, VE },
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{ "dst_v_chr_pos", "destination vertical chroma position in luma grid/256" , OFFSET(dst_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 512, VE },
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{ "dst_h_chr_pos", "destination horizontal chroma position in luma grid/256", OFFSET(dst_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 512, VE },
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{ "sws_dither", "set dithering algorithm", OFFSET(dither), AV_OPT_TYPE_INT, { .i64 = SWS_DITHER_AUTO }, 0, NB_SWS_DITHER, VE, "sws_dither" },
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{ "auto", "leave choice to sws", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_DITHER_AUTO }, INT_MIN, INT_MAX, VE, "sws_dither" },
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{ "bayer", "bayer dither", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_DITHER_BAYER }, INT_MIN, INT_MAX, VE, "sws_dither" },
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{ "ed", "error diffusion", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_DITHER_ED }, INT_MIN, INT_MAX, VE, "sws_dither" },
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{ "a_dither", "arithmetic addition dither", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_DITHER_A_DITHER}, INT_MIN, INT_MAX, VE, "sws_dither" },
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{ "x_dither", "arithmetic xor dither", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_DITHER_X_DITHER}, INT_MIN, INT_MAX, VE, "sws_dither" },
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{ NULL }
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};
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const AVClass sws_context_class = {
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.class_name = "SWScaler",
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.item_name = sws_context_to_name,
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.option = swscale_options,
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.category = AV_CLASS_CATEGORY_SWSCALER,
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.version = LIBAVUTIL_VERSION_INT,
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};
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const AVClass *sws_get_class(void)
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{
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return &sws_context_class;
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}
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