Hamsalekha S | 8d3d303 | 2015-03-13 21:24:58 +0530 | [diff] [blame] | 1 | /****************************************************************************** |
| 2 | * |
| 3 | * Copyright (C) 2015 The Android Open Source Project |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at: |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | ***************************************************************************** |
| 18 | * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore |
| 19 | */ |
| 20 | |
| 21 | /** |
| 22 | ******************************************************************************* |
| 23 | * @file |
| 24 | * ih264e_globals.h |
| 25 | * |
| 26 | * @brief |
| 27 | * Contains declarations of global variables for H264 encoder |
| 28 | * |
| 29 | * @author |
| 30 | * Ittiam |
| 31 | * |
| 32 | * @remarks |
| 33 | * |
| 34 | ******************************************************************************* |
| 35 | */ |
| 36 | |
| 37 | #ifndef IH264E_GLOBALS_H_ |
| 38 | #define IH264E_GLOBALS_H_ |
| 39 | |
| 40 | |
| 41 | /*****************************************************************************/ |
| 42 | /* Extern global declarations */ |
| 43 | /*****************************************************************************/ |
| 44 | |
| 45 | /** |
| 46 | ****************************************************************************** |
| 47 | * @brief Computes the lamda for varying quantizer scales that would be used to |
| 48 | * compute the RD cost while deciding on the MB modes. |
| 49 | * input : qp |
| 50 | * output : lambda |
| 51 | * @remarks lambda = 0.85 * pow(2, (qp - 12)/3), when SSD is used as metric |
| 52 | * for computing distortion (Bit rate estimation for cost function of H.264/ |
| 53 | * AVC by Mohd Golam Sarwer et. al.) If the use of distortion metric is SAD |
| 54 | * rather than SSD in the stage of encoding, consider sqrt(lambda) simply to |
| 55 | * adjust lambda for the lack of squaring operation in the error computation |
| 56 | * (from rate distortion optimization for video compression by sullivan). |
| 57 | ****************************************************************************** |
| 58 | */ |
| 59 | extern const UWORD16 gu2_qp_lambda[52]; |
| 60 | |
| 61 | /** |
| 62 | ****************************************************************************** |
| 63 | * @brief Computes the lamda for varying quantizer scales that would be used to |
| 64 | * compute the RD cost while deciding on the MB modes. |
| 65 | * input : qp |
| 66 | * output : lambda |
| 67 | * @remarks lambda = pow(2, (qp - 12)/6). When Lagrangian multiplier is disabled |
| 68 | * the same constant is used across mode decision and mv decisions. |
| 69 | ****************************************************************************** |
| 70 | */ |
| 71 | extern const UWORD8 gu1_qp0[52]; |
| 72 | |
| 73 | /** |
| 74 | ****************************************************************************** |
| 75 | * @brief unsigned exp. goulumb codelengths to assign cost to a coefficient of |
| 76 | * mb types. |
| 77 | * input : Integer |
| 78 | * output : codelength |
| 79 | * @remarks Refer sec. 9-1 in h264 specification |
| 80 | ****************************************************************************** |
| 81 | */ |
| 82 | extern const UWORD8 u1_uev_codelength[32]; |
| 83 | |
| 84 | /** |
| 85 | ****************************************************************************** |
| 86 | * @brief Look up table to assign cost to a coefficient of a residual block |
| 87 | * basing on its surrounding coefficients |
| 88 | * input : Numbers of T1's |
| 89 | * output : coeff_cost |
| 90 | * @remarks Refer Section 2.3 Elimination of single coefficients in inter |
| 91 | * macroblocks in document JVT-O079 |
| 92 | ****************************************************************************** |
| 93 | */ |
| 94 | extern const UWORD8 gu1_coeff_cost[6]; |
| 95 | |
| 96 | /** |
| 97 | ****************************************************************************** |
| 98 | * @brief Indices map to raster scan for luma 4x4 block |
| 99 | * input : scan index |
| 100 | * output : scan location |
| 101 | * @remarks The scan order assumes the stride to access the next row is 16 |
| 102 | ****************************************************************************** |
| 103 | */ |
| 104 | extern const UWORD8 gu1_luma_scan_order[16]; |
| 105 | |
| 106 | /** |
| 107 | ****************************************************************************** |
| 108 | * @brief Indices map to raster scan for chroma AC block |
| 109 | * input : scan index |
| 110 | * output : scan location |
| 111 | * @remarks The scan order assumes the stride to access the next row is 32 |
| 112 | ****************************************************************************** |
| 113 | */ |
| 114 | extern const UWORD8 gu1_chroma_scan_order[15]; |
| 115 | |
| 116 | /** |
| 117 | ****************************************************************************** |
| 118 | * @brief Indices map to raster scan for luma 4x4 dc block |
| 119 | * input : scan index |
| 120 | * output : scan location |
| 121 | * @remarks The scan order assumes the stride to access the next row is 16 |
| 122 | ****************************************************************************** |
| 123 | */ |
| 124 | extern const UWORD8 gu1_luma_scan_order_dc[16]; |
| 125 | |
| 126 | /** |
| 127 | ****************************************************************************** |
| 128 | * @brief Indices map to raster scan for chroma 2x2 dc block |
| 129 | * input : scan index |
| 130 | * output : scan location |
| 131 | * @remarks The scan order assumes the stride to access the next row is 16 |
| 132 | ****************************************************************************** |
| 133 | */ |
| 134 | extern const UWORD8 gu1_chroma_scan_order_dc[4]; |
| 135 | |
| 136 | |
| 137 | /** |
| 138 | ****************************************************************************** |
| 139 | * @brief choice of motion vectors to be used during mv prediction |
| 140 | * input : formatted reference idx comparison metric |
| 141 | * output : mv prediction has to be median or a simple straight forward selec |
| 142 | * tion from neighbors. |
| 143 | * @remarks If only one of the candidate blocks has a reference frame equal to |
| 144 | the current block then use the same block as the final predictor. A simple |
| 145 | look up table to assist this mv prediction condition |
| 146 | ****************************************************************************** |
| 147 | */ |
| 148 | extern const WORD8 gi1_mv_pred_condition[8]; |
| 149 | |
| 150 | |
| 151 | /** |
| 152 | ****************************************************************************** |
| 153 | * @brief maps the h264 quantizer to the mpeg2 quantizer scale |
| 154 | * input : h264 qp |
| 155 | * output : eqvivalent mpeg 2 qp |
| 156 | * @remarks mpeg2qscale = 2 ^ [((h264qp - 12) / 6) + 1] |
| 157 | ****************************************************************************** |
| 158 | */ |
| 159 | extern const UWORD8 gau1_h264_to_mpeg2_qmap[H264_QP_ELEM]; |
| 160 | |
| 161 | /** |
| 162 | ****************************************************************************** |
| 163 | * @brief maps the mpeg2 quantizer to the h264 quantizer scale |
| 164 | * input : mpeg2 qp |
| 165 | * output : eqvivalent h264q p |
| 166 | * @remarks MPEG-2 dequantization: (2*QFij + k)*Wij*qscale/32 |
| 167 | * k = 0 (for intra) k = sign(QFij) |
| 168 | * H.264 dequantization: (QFij*R(QP%6,i,j))>>(6 - QP/6) |
| 169 | * |
| 170 | * Excluding the portion of R(QP%6,i,j) that is due to |
| 171 | * the DCT scale factors, the 6 entries after dividing by 64 (2^6) |
| 172 | * correspond to dequant values of |
| 173 | * 2.5, 2.8125, 3.125, 3.5625, 3.9375, 4.4375. |
| 174 | * (a=0.5 b=sqrt(2/5) - refer to JVT-B038.doc) |
| 175 | * |
| 176 | * Assuming that h264Qp=12 corresponds to MPEG2 qscale of 2 |
| 177 | * (the actual mapping seems to be to MPEG2 qscale of 2.5), |
| 178 | * and the fact that the effective h264 quantizer changes by |
| 179 | * a factor of 2 for every 6 steps, the following mapping is |
| 180 | * obtained: |
| 181 | * h264qp = 6*(log2(mpeg2qscale/2)) + 12. |
| 182 | * |
| 183 | * Note that the quant matrix entry assumed for the above |
| 184 | * equality is 16. Hence when the mpeg2 quant matrix entries |
| 185 | * are all 16, this lookup can be used as is (which is the |
| 186 | * default inter quant matrix in mpeg-2). |
| 187 | ****************************************************************************** |
| 188 | */ |
| 189 | extern const UWORD8 gau1_mpeg2_to_h264_qmap[MPEG2_QP_ELEM]; |
| 190 | |
| 191 | |
| 192 | #endif /* IH264E_GLOBALS_H_ */ |