1 // Copyright 2010 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Quantizer initialization
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13
14 #include "./vp8i.h"
15
16 #if defined(__cplusplus) || defined(c_plusplus)
17 extern "C" {
18 #endif
19
clip(int v,int M)20 static WEBP_INLINE int clip(int v, int M) {
21 return v < 0 ? 0 : v > M ? M : v;
22 }
23
24 // Paragraph 14.1
25 static const uint8_t kDcTable[128] = {
26 4, 5, 6, 7, 8, 9, 10, 10,
27 11, 12, 13, 14, 15, 16, 17, 17,
28 18, 19, 20, 20, 21, 21, 22, 22,
29 23, 23, 24, 25, 25, 26, 27, 28,
30 29, 30, 31, 32, 33, 34, 35, 36,
31 37, 37, 38, 39, 40, 41, 42, 43,
32 44, 45, 46, 46, 47, 48, 49, 50,
33 51, 52, 53, 54, 55, 56, 57, 58,
34 59, 60, 61, 62, 63, 64, 65, 66,
35 67, 68, 69, 70, 71, 72, 73, 74,
36 75, 76, 76, 77, 78, 79, 80, 81,
37 82, 83, 84, 85, 86, 87, 88, 89,
38 91, 93, 95, 96, 98, 100, 101, 102,
39 104, 106, 108, 110, 112, 114, 116, 118,
40 122, 124, 126, 128, 130, 132, 134, 136,
41 138, 140, 143, 145, 148, 151, 154, 157
42 };
43
44 static const uint16_t kAcTable[128] = {
45 4, 5, 6, 7, 8, 9, 10, 11,
46 12, 13, 14, 15, 16, 17, 18, 19,
47 20, 21, 22, 23, 24, 25, 26, 27,
48 28, 29, 30, 31, 32, 33, 34, 35,
49 36, 37, 38, 39, 40, 41, 42, 43,
50 44, 45, 46, 47, 48, 49, 50, 51,
51 52, 53, 54, 55, 56, 57, 58, 60,
52 62, 64, 66, 68, 70, 72, 74, 76,
53 78, 80, 82, 84, 86, 88, 90, 92,
54 94, 96, 98, 100, 102, 104, 106, 108,
55 110, 112, 114, 116, 119, 122, 125, 128,
56 131, 134, 137, 140, 143, 146, 149, 152,
57 155, 158, 161, 164, 167, 170, 173, 177,
58 181, 185, 189, 193, 197, 201, 205, 209,
59 213, 217, 221, 225, 229, 234, 239, 245,
60 249, 254, 259, 264, 269, 274, 279, 284
61 };
62
63 //------------------------------------------------------------------------------
64 // Paragraph 9.6
65
VP8ParseQuant(VP8Decoder * const dec)66 void VP8ParseQuant(VP8Decoder* const dec) {
67 VP8BitReader* const br = &dec->br_;
68 const int base_q0 = VP8GetValue(br, 7);
69 const int dqy1_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
70 const int dqy2_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
71 const int dqy2_ac = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
72 const int dquv_dc = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
73 const int dquv_ac = VP8Get(br) ? VP8GetSignedValue(br, 4) : 0;
74
75 const VP8SegmentHeader* const hdr = &dec->segment_hdr_;
76 int i;
77
78 for (i = 0; i < NUM_MB_SEGMENTS; ++i) {
79 int q;
80 if (hdr->use_segment_) {
81 q = hdr->quantizer_[i];
82 if (!hdr->absolute_delta_) {
83 q += base_q0;
84 }
85 } else {
86 if (i > 0) {
87 dec->dqm_[i] = dec->dqm_[0];
88 continue;
89 } else {
90 q = base_q0;
91 }
92 }
93 {
94 VP8QuantMatrix* const m = &dec->dqm_[i];
95 m->y1_mat_[0] = kDcTable[clip(q + dqy1_dc, 127)];
96 m->y1_mat_[1] = kAcTable[clip(q + 0, 127)];
97
98 m->y2_mat_[0] = kDcTable[clip(q + dqy2_dc, 127)] * 2;
99 // For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16.
100 // The smallest precision for that is '(x*6349) >> 12' but 16 is a good
101 // word size.
102 m->y2_mat_[1] = (kAcTable[clip(q + dqy2_ac, 127)] * 101581) >> 16;
103 if (m->y2_mat_[1] < 8) m->y2_mat_[1] = 8;
104
105 m->uv_mat_[0] = kDcTable[clip(q + dquv_dc, 117)];
106 m->uv_mat_[1] = kAcTable[clip(q + dquv_ac, 127)];
107 }
108 }
109 }
110
111 //------------------------------------------------------------------------------
112
113 #if defined(__cplusplus) || defined(c_plusplus)
114 } // extern "C"
115 #endif
116