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 (at) gmail.com) 13 14 #include "./vp8i.h" 15 16 #if defined(__cplusplus) || defined(c_plusplus) 17 extern "C" { 18 #endif 19 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 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
