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libavcodec/jpegls.c

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00001 /*
00002  * JPEG-LS common code
00003  * Copyright (c) 2003 Michael Niedermayer
00004  * Copyright (c) 2006 Konstantin Shishkov
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00028 #include "jpegls.h"
00029 
00030 void ff_jpegls_init_state(JLSState *state){
00031     int i;
00032 
00033     state->twonear = state->near * 2 + 1;
00034     state->range = ((state->maxval + state->twonear - 1) / state->twonear) + 1;
00035 
00036     // QBPP = ceil(log2(RANGE))
00037     for(state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++);
00038 
00039     if(state->bpp < 8)
00040         state->limit = 16 + 2 * state->bpp - state->qbpp;
00041     else
00042         state->limit = (4 * state->bpp) - state->qbpp;
00043 
00044     for(i = 0; i < 367; i++) {
00045         state->A[i] = FFMAX((state->range + 32) >> 6, 2);
00046         state->N[i] = 1;
00047     }
00048 
00049 }
00050 
00054 static inline int iso_clip(int v, int vmin, int vmax){
00055     if(v > vmax || v < vmin) return vmin;
00056     else                     return v;
00057 }
00058 
00059 void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all){
00060     const int basic_t1= 3;
00061     const int basic_t2= 7;
00062     const int basic_t3= 21;
00063     int factor;
00064 
00065     if(s->maxval==0 || reset_all) s->maxval= (1 << s->bpp) - 1;
00066 
00067     if(s->maxval >=128){
00068         factor= (FFMIN(s->maxval, 4095) + 128)>>8;
00069 
00070         if(s->T1==0     || reset_all)
00071             s->T1= iso_clip(factor*(basic_t1-2) + 2 + 3*s->near, s->near+1, s->maxval);
00072         if(s->T2==0     || reset_all)
00073             s->T2= iso_clip(factor*(basic_t2-3) + 3 + 5*s->near, s->T1, s->maxval);
00074         if(s->T3==0     || reset_all)
00075             s->T3= iso_clip(factor*(basic_t3-4) + 4 + 7*s->near, s->T2, s->maxval);
00076     }else{
00077         factor= 256 / (s->maxval + 1);
00078 
00079         if(s->T1==0     || reset_all)
00080             s->T1= iso_clip(FFMAX(2, basic_t1/factor + 3*s->near), s->near+1, s->maxval);
00081         if(s->T2==0     || reset_all)
00082             s->T2= iso_clip(FFMAX(3, basic_t2/factor + 5*s->near), s->T1, s->maxval);
00083         if(s->T3==0     || reset_all)
00084             s->T3= iso_clip(FFMAX(4, basic_t3/factor + 7*s->near), s->T2, s->maxval);
00085     }
00086 
00087     if(s->reset==0  || reset_all) s->reset= 64;
00088 //    av_log(NULL, AV_LOG_DEBUG, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
00089 }

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