101 lines
3.1 KiB
C
101 lines
3.1 KiB
C
/*
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* JPEG-LS common code
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* Copyright (c) 2003 Michael Niedermayer
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* Copyright (c) 2006 Konstantin Shishkov
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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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/**
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* @file
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* JPEG-LS common code.
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*/
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#include "jpegls.h"
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void ff_jpegls_init_state(JLSState *state)
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{
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int i;
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state->twonear = state->near * 2 + 1;
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state->range = (state->maxval + state->twonear - 1) / state->twonear + 1;
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// QBPP = ceil(log2(RANGE))
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for (state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++)
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;
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state->bpp = FFMAX(av_log2(state->maxval) + 1, 2);
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state->limit = 2*(state->bpp + FFMAX(state->bpp, 8)) - state->qbpp;
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for (i = 0; i < 367; i++) {
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state->A[i] = FFMAX(state->range + 32 >> 6, 2);
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state->N[i] = 1;
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}
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}
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/**
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* Custom value clipping function used in T1, T2, T3 calculation
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*/
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static inline int iso_clip(int v, int vmin, int vmax)
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{
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if (v > vmax || v < vmin)
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return vmin;
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else
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return v;
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}
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void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
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{
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const int basic_t1 = 3;
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const int basic_t2 = 7;
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const int basic_t3 = 21;
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int factor;
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if (s->maxval == 0 || reset_all)
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s->maxval = (1 << s->bpp) - 1;
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if (s->maxval >= 128) {
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factor = FFMIN(s->maxval, 4095) + 128 >> 8;
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if (s->T1 == 0 || reset_all)
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s->T1 = iso_clip(factor * (basic_t1 - 2) + 2 + 3 * s->near,
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s->near + 1, s->maxval);
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if (s->T2 == 0 || reset_all)
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s->T2 = iso_clip(factor * (basic_t2 - 3) + 3 + 5 * s->near,
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s->T1, s->maxval);
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if (s->T3 == 0 || reset_all)
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s->T3 = iso_clip(factor * (basic_t3 - 4) + 4 + 7 * s->near,
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s->T2, s->maxval);
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} else {
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factor = 256 / (s->maxval + 1);
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if (s->T1 == 0 || reset_all)
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s->T1 = iso_clip(FFMAX(2, basic_t1 / factor + 3 * s->near),
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s->near + 1, s->maxval);
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if (s->T2 == 0 || reset_all)
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s->T2 = iso_clip(FFMAX(3, basic_t2 / factor + 5 * s->near),
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s->T1, s->maxval);
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if (s->T3 == 0 || reset_all)
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s->T3 = iso_clip(FFMAX(4, basic_t3 / factor + 7 * s->near),
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s->T2, s->maxval);
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}
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if (s->reset == 0 || reset_all)
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s->reset = 64;
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av_dlog(NULL, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
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}
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