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