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 (at) gmail.com) 11 12 #include "./vp8i.h" 13 14 #if defined(__cplusplus) || defined(c_plusplus) 15 extern "C" { 16 #endif 17 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 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
