ffmpeg/libavcodec/jpegls.h

   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 */