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jpegls.h
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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 "avcodec.h"
32 #include "libavutil/common.h"
33 
34 typedef struct JpeglsContext{
38 
39 typedef struct JLSState{
40  int T1, T2, T3;
41  int A[367], B[367], C[365], N[367];
43  int near, twonear;
44  int run_index[4];
45 }JLSState;
46 
47 extern const uint8_t ff_log2_run[32];
48 
49 /**
50  * Calculate initial JPEG-LS parameters
51  */
53 
54 /**
55  * Calculate quantized gradient value, used for context determination
56  */
57 static inline int ff_jpegls_quantize(JLSState *s, int v){ //FIXME optimize
58  if(v==0) return 0;
59  if(v < 0){
60  if(v <= -s->T3) return -4;
61  if(v <= -s->T2) return -3;
62  if(v <= -s->T1) return -2;
63  if(v < -s->near) return -1;
64  return 0;
65  }else{
66  if(v <= s->near) return 0;
67  if(v < s->T1) return 1;
68  if(v < s->T2) return 2;
69  if(v < s->T3) return 3;
70  return 4;
71  }
72 }
73 
74 /**
75  * Calculate JPEG-LS codec values
76  */
77 void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all);
78 
79 
80 static inline void ff_jpegls_downscale_state(JLSState *state, int Q){
81  if(state->N[Q] == state->reset){
82  state->A[Q] >>=1;
83  state->B[Q] >>=1;
84  state->N[Q] >>=1;
85  }
86  state->N[Q]++;
87 }
88 
89 static inline int ff_jpegls_update_state_regular(JLSState *state, int Q, int err){
90  if(FFABS(err) > 0xFFFF)
91  return -0x10000;
92  state->A[Q] += FFABS(err);
93  err *= state->twonear;
94  state->B[Q] += err;
95 
96  ff_jpegls_downscale_state(state, Q);
97 
98  if(state->B[Q] <= -state->N[Q]) {
99  state->B[Q]= FFMAX(state->B[Q] + state->N[Q], 1-state->N[Q]);
100  if(state->C[Q] > -128)
101  state->C[Q]--;
102  }else if(state->B[Q] > 0){
103  state->B[Q]= FFMIN(state->B[Q] - state->N[Q], 0);
104  if(state->C[Q] < 127)
105  state->C[Q]++;
106  }
107 
108  return err;
109 }
110 
111 #define R(a, i ) (bits == 8 ? ((uint8_t*)(a))[i] : ((uint16_t*)(a))[i] )
112 #define W(a, i, v) (bits == 8 ? (((uint8_t*)(a))[i]=v) : (((uint16_t*)(a))[i]=v))
113 
114 #endif /* AVCODEC_JPEGLS_H */