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 "src/dec/vp8i_dec.h" |
15 | |
16 | static WEBP_INLINE int clip(int v, int M) { |
17 | return v < 0 ? 0 : v > M ? M : v; |
18 | } |
19 | |
20 | // Paragraph 14.1 |
21 | static const uint8_t kDcTable[128] = { |
22 | 4, 5, 6, 7, 8, 9, 10, 10, |
23 | 11, 12, 13, 14, 15, 16, 17, 17, |
24 | 18, 19, 20, 20, 21, 21, 22, 22, |
25 | 23, 23, 24, 25, 25, 26, 27, 28, |
26 | 29, 30, 31, 32, 33, 34, 35, 36, |
27 | 37, 37, 38, 39, 40, 41, 42, 43, |
28 | 44, 45, 46, 46, 47, 48, 49, 50, |
29 | 51, 52, 53, 54, 55, 56, 57, 58, |
30 | 59, 60, 61, 62, 63, 64, 65, 66, |
31 | 67, 68, 69, 70, 71, 72, 73, 74, |
32 | 75, 76, 76, 77, 78, 79, 80, 81, |
33 | 82, 83, 84, 85, 86, 87, 88, 89, |
34 | 91, 93, 95, 96, 98, 100, 101, 102, |
35 | 104, 106, 108, 110, 112, 114, 116, 118, |
36 | 122, 124, 126, 128, 130, 132, 134, 136, |
37 | 138, 140, 143, 145, 148, 151, 154, 157 |
38 | }; |
39 | |
40 | static const uint16_t kAcTable[128] = { |
41 | 4, 5, 6, 7, 8, 9, 10, 11, |
42 | 12, 13, 14, 15, 16, 17, 18, 19, |
43 | 20, 21, 22, 23, 24, 25, 26, 27, |
44 | 28, 29, 30, 31, 32, 33, 34, 35, |
45 | 36, 37, 38, 39, 40, 41, 42, 43, |
46 | 44, 45, 46, 47, 48, 49, 50, 51, |
47 | 52, 53, 54, 55, 56, 57, 58, 60, |
48 | 62, 64, 66, 68, 70, 72, 74, 76, |
49 | 78, 80, 82, 84, 86, 88, 90, 92, |
50 | 94, 96, 98, 100, 102, 104, 106, 108, |
51 | 110, 112, 114, 116, 119, 122, 125, 128, |
52 | 131, 134, 137, 140, 143, 146, 149, 152, |
53 | 155, 158, 161, 164, 167, 170, 173, 177, |
54 | 181, 185, 189, 193, 197, 201, 205, 209, |
55 | 213, 217, 221, 225, 229, 234, 239, 245, |
56 | 249, 254, 259, 264, 269, 274, 279, 284 |
57 | }; |
58 | |
59 | //------------------------------------------------------------------------------ |
60 | // Paragraph 9.6 |
61 | |
62 | void VP8ParseQuant(VP8Decoder* const dec) { |
63 | VP8BitReader* const br = &dec->br_; |
64 | const int base_q0 = VP8GetValue(br, 7, "global-header" ); |
65 | const int dqy1_dc = VP8Get(br, "global-header" ) ? |
66 | VP8GetSignedValue(br, 4, "global-header" ) : 0; |
67 | const int dqy2_dc = VP8Get(br, "global-header" ) ? |
68 | VP8GetSignedValue(br, 4, "global-header" ) : 0; |
69 | const int dqy2_ac = VP8Get(br, "global-header" ) ? |
70 | VP8GetSignedValue(br, 4, "global-header" ) : 0; |
71 | const int dquv_dc = VP8Get(br, "global-header" ) ? |
72 | VP8GetSignedValue(br, 4, "global-header" ) : 0; |
73 | const int dquv_ac = VP8Get(br, "global-header" ) ? |
74 | VP8GetSignedValue(br, 4, "global-header" ) : 0; |
75 | |
76 | const VP8SegmentHeader* const hdr = &dec->segment_hdr_; |
77 | int i; |
78 | |
79 | for (i = 0; i < NUM_MB_SEGMENTS; ++i) { |
80 | int q; |
81 | if (hdr->use_segment_) { |
82 | q = hdr->quantizer_[i]; |
83 | if (!hdr->absolute_delta_) { |
84 | q += base_q0; |
85 | } |
86 | } else { |
87 | if (i > 0) { |
88 | dec->dqm_[i] = dec->dqm_[0]; |
89 | continue; |
90 | } else { |
91 | q = base_q0; |
92 | } |
93 | } |
94 | { |
95 | VP8QuantMatrix* const m = &dec->dqm_[i]; |
96 | m->y1_mat_[0] = kDcTable[clip(q + dqy1_dc, 127)]; |
97 | m->y1_mat_[1] = kAcTable[clip(q + 0, 127)]; |
98 | |
99 | m->y2_mat_[0] = kDcTable[clip(q + dqy2_dc, 127)] * 2; |
100 | // For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16. |
101 | // The smallest precision for that is '(x*6349) >> 12' but 16 is a good |
102 | // word size. |
103 | m->y2_mat_[1] = (kAcTable[clip(q + dqy2_ac, 127)] * 101581) >> 16; |
104 | if (m->y2_mat_[1] < 8) m->y2_mat_[1] = 8; |
105 | |
106 | m->uv_mat_[0] = kDcTable[clip(q + dquv_dc, 117)]; |
107 | m->uv_mat_[1] = kAcTable[clip(q + dquv_ac, 127)]; |
108 | |
109 | m->uv_quant_ = q + dquv_ac; // for dithering strength evaluation |
110 | } |
111 | } |
112 | } |
113 | |
114 | //------------------------------------------------------------------------------ |
115 | |
116 | |