libavcodec/jpegls.c

   1 /*
   2  * JPEG-LS common code
   3  * Copyright (c) 2003 Michael Niedermayer
   4  * Copyright (c) 2006 Konstantin Shishkov
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file libavcodec/jpegls.c
  25  * JPEG-LS common code.
  26  */
  27
  28 #include "jpegls.h"
  29
  30 void ff_jpegls_init_state(JLSState *state){
  31     int i;
  32
  33     state->twonear = state->near * 2 + 1;
  34     state->range = ((state->maxval + state->twonear - 1) / state->twonear) + 1;
  35
  36     // QBPP = ceil(log2(RANGE))
  37     for(state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++);
  38
  39     if(state->bpp < 8)
  40         state->limit = 16 + 2 * state->bpp - state->qbpp;
  41     else
  42         state->limit = (4 * state->bpp) - state->qbpp;
  43
  44     for(i = 0; i < 367; i++) {
  45         state->A[i] = FFMAX((state->range + 32) >> 6, 2);
  46         state->N[i] = 1;
  47     }
  48
  49 }
  50
  51 /**
  52  * Custom value clipping function used in T1, T2, T3 calculation
  53  */
  54 static inline int iso_clip(int v, int vmin, int vmax){
  55     if(v > vmax || v < vmin) return vmin;
  56     else                     return v;
  57 }
  58
  59 void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all){
  60     const int basic_t1= 3;
  61     const int basic_t2= 7;
  62     const int basic_t3= 21;
  63     int factor;
  64
  65     if(s->maxval==0 || reset_all) s->maxval= (1 << s->bpp) - 1;
  66
  67     if(s->maxval >=128){
  68         factor= (FFMIN(s->maxval, 4095) + 128)>>8;
  69
  70         if(s->T1==0     || reset_all)
  71             s->T1= iso_clip(factor*(basic_t1-2) + 2 + 3*s->near, s->near+1, s->maxval);
  72         if(s->T2==0     || reset_all)
  73             s->T2= iso_clip(factor*(basic_t2-3) + 3 + 5*s->near, s->T1, s->maxval);
  74         if(s->T3==0     || reset_all)
  75             s->T3= iso_clip(factor*(basic_t3-4) + 4 + 7*s->near, s->T2, s->maxval);
  76     }else{
  77         factor= 256 / (s->maxval + 1);
  78
  79         if(s->T1==0     || reset_all)
  80             s->T1= iso_clip(FFMAX(2, basic_t1/factor + 3*s->near), s->near+1, s->maxval);
  81         if(s->T2==0     || reset_all)
  82             s->T2= iso_clip(FFMAX(3, basic_t2/factor + 5*s->near), s->T1, s->maxval);
  83         if(s->T3==0     || reset_all)
  84             s->T3= iso_clip(FFMAX(4, basic_t3/factor + 7*s->near), s->T2, s->maxval);
  85     }
  86
  87     if(s->reset==0  || reset_all) s->reset= 64;
  88 //    av_log(NULL, AV_LOG_DEBUG, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
  89 }