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  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
  25.  * JPEG-LS common code.
  26.  */
  27.  
  28. #ifndef AVCODEC_JPEGLS_H
  29. #define AVCODEC_JPEGLS_H
  30.  
  31. #include "libavutil/common.h"
  32. #include "avcodec.h"
  33. #include "internal.h"
  34.  
  35. typedef struct JpeglsContext {
  36.     AVCodecContext *avctx;
  37. } JpeglsContext;
  38.  
  39. typedef struct JLSState {
  40.     int T1, T2, T3;
  41.     int A[367], B[367], C[365], N[367];
  42.     int limit, reset, bpp, qbpp, maxval, range;
  43.     int near, twonear;
  44.     int run_index[4];
  45. } JLSState;
  46.  
  47. /**
  48.  * Calculate initial JPEG-LS parameters
  49.  */
  50. void ff_jpegls_init_state(JLSState *state);
  51.  
  52. /**
  53.  * Calculate quantized gradient value, used for context determination
  54.  */
  55. static inline int ff_jpegls_quantize(JLSState *s, int v)
  56. {
  57.     if (v == 0)
  58.         return 0;
  59.     if (v < 0) {
  60.         if (v <= -s->T3)
  61.             return -4;
  62.         if (v <= -s->T2)
  63.             return -3;
  64.         if (v <= -s->T1)
  65.             return -2;
  66.         if (v < -s->near)
  67.             return -1;
  68.         return 0;
  69.     } else {
  70.         if (v <= s->near)
  71.             return 0;
  72.         if (v < s->T1)
  73.             return 1;
  74.         if (v < s->T2)
  75.             return 2;
  76.         if (v < s->T3)
  77.             return 3;
  78.         return 4;
  79.     }
  80. }
  81.  
  82. /**
  83.  * Calculate JPEG-LS codec values
  84.  */
  85. void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all);
  86.  
  87. static inline void ff_jpegls_downscale_state(JLSState *state, int Q)
  88. {
  89.     if (state->N[Q] == state->reset) {
  90.         state->A[Q] >>= 1;
  91.         state->B[Q] >>= 1;
  92.         state->N[Q] >>= 1;
  93.     }
  94.     state->N[Q]++;
  95. }
  96.  
  97. static inline int ff_jpegls_update_state_regular(JLSState *state,
  98.                                                  int Q, int err)
  99. {
  100.     if(FFABS(err) > 0xFFFF)
  101.         return -0x10000;
  102.     state->A[Q] += FFABS(err);
  103.     err         *= state->twonear;
  104.     state->B[Q] += err;
  105.  
  106.     ff_jpegls_downscale_state(state, Q);
  107.  
  108.     if (state->B[Q] <= -state->N[Q]) {
  109.         state->B[Q] = FFMAX(state->B[Q] + state->N[Q], 1 - state->N[Q]);
  110.         if (state->C[Q] > -128)
  111.             state->C[Q]--;
  112.     } else if (state->B[Q] > 0) {
  113.         state->B[Q] = FFMIN(state->B[Q] - state->N[Q], 0);
  114.         if (state->C[Q] < 127)
  115.             state->C[Q]++;
  116.     }
  117.  
  118.     return err;
  119. }
  120.  
  121. #define R(a, i)    (bits == 8 ?  ((uint8_t *)(a))[i]      :  ((uint16_t *)(a))[i])
  122. #define W(a, i, v) (bits == 8 ? (((uint8_t *)(a))[i] = v) : (((uint16_t *)(a))[i] = v))
  123.  
  124. #endif /* AVCODEC_JPEGLS_H */
  125.