| /****************************************************************************** |
| * |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at: |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| ***************************************************************************** |
| * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore |
| */ |
| |
| /** |
| ******************************************************************************* |
| * @file |
| * ih264e_globals.h |
| * |
| * @brief |
| * Contains declarations of global variables for H264 encoder |
| * |
| * @author |
| * Ittiam |
| * |
| * @remarks |
| * |
| ******************************************************************************* |
| */ |
| |
| #ifndef IH264E_GLOBALS_H_ |
| #define IH264E_GLOBALS_H_ |
| |
| |
| /*****************************************************************************/ |
| /* Extern global declarations */ |
| /*****************************************************************************/ |
| |
| /** |
| ****************************************************************************** |
| * @brief Computes the lamda for varying quantizer scales that would be used to |
| * compute the RD cost while deciding on the MB modes. |
| * input : qp |
| * output : lambda |
| * @remarks lambda = 0.85 * pow(2, (qp - 12)/3), when SSD is used as metric |
| * for computing distortion (Bit rate estimation for cost function of H.264/ |
| * AVC by Mohd Golam Sarwer et. al.) If the use of distortion metric is SAD |
| * rather than SSD in the stage of encoding, consider sqrt(lambda) simply to |
| * adjust lambda for the lack of squaring operation in the error computation |
| * (from rate distortion optimization for video compression by sullivan). |
| ****************************************************************************** |
| */ |
| extern const UWORD16 gu2_qp_lambda[52]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Computes the lamda for varying quantizer scales that would be used to |
| * compute the RD cost while deciding on the MB modes. |
| * input : qp |
| * output : lambda |
| * @remarks lambda = pow(2, (qp - 12)/6). When Lagrangian multiplier is disabled |
| * the same constant is used across mode decision and mv decisions. |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_qp0[52]; |
| |
| /** |
| ****************************************************************************** |
| * @brief unsigned exp. goulumb codelengths to assign cost to a coefficient of |
| * mb types. |
| * input : Integer |
| * output : codelength |
| * @remarks Refer sec. 9-1 in h264 specification |
| ****************************************************************************** |
| */ |
| extern const UWORD8 u1_uev_codelength[32]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Look up table to assign cost to a coefficient of a residual block |
| * basing on its surrounding coefficients |
| * input : Numbers of T1's |
| * output : coeff_cost |
| * @remarks Refer Section 2.3 Elimination of single coefficients in inter |
| * macroblocks in document JVT-O079 |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_coeff_cost[6]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Indices map to raster scan for luma 4x4 block |
| * input : scan index |
| * output : scan location |
| * @remarks The scan order assumes the stride to access the next row is 16 |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_luma_scan_order[16]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Indices map to raster scan for chroma AC block |
| * input : scan index |
| * output : scan location |
| * @remarks The scan order assumes the stride to access the next row is 32 |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_chroma_scan_order[15]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Indices map to raster scan for luma 4x4 dc block |
| * input : scan index |
| * output : scan location |
| * @remarks The scan order assumes the stride to access the next row is 16 |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_luma_scan_order_dc[16]; |
| |
| /** |
| ****************************************************************************** |
| * @brief Indices map to raster scan for chroma 2x2 dc block |
| * input : scan index |
| * output : scan location |
| * @remarks The scan order assumes the stride to access the next row is 16 |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gu1_chroma_scan_order_dc[4]; |
| |
| |
| /** |
| ****************************************************************************** |
| * @brief choice of motion vectors to be used during mv prediction |
| * input : formatted reference idx comparison metric |
| * output : mv prediction has to be median or a simple straight forward selec |
| * tion from neighbors. |
| * @remarks If only one of the candidate blocks has a reference frame equal to |
| the current block then use the same block as the final predictor. A simple |
| look up table to assist this mv prediction condition |
| ****************************************************************************** |
| */ |
| extern const WORD8 gi1_mv_pred_condition[8]; |
| |
| |
| /** |
| ****************************************************************************** |
| * @brief maps the h264 quantizer to the mpeg2 quantizer scale |
| * input : h264 qp |
| * output : eqvivalent mpeg 2 qp |
| * @remarks mpeg2qscale = 2 ^ [((h264qp - 12) / 6) + 1] |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gau1_h264_to_mpeg2_qmap[H264_QP_ELEM]; |
| |
| /** |
| ****************************************************************************** |
| * @brief maps the mpeg2 quantizer to the h264 quantizer scale |
| * input : mpeg2 qp |
| * output : eqvivalent h264q p |
| * @remarks MPEG-2 dequantization: (2*QFij + k)*Wij*qscale/32 |
| * k = 0 (for intra) k = sign(QFij) |
| * H.264 dequantization: (QFij*R(QP%6,i,j))>>(6 - QP/6) |
| * |
| * Excluding the portion of R(QP%6,i,j) that is due to |
| * the DCT scale factors, the 6 entries after dividing by 64 (2^6) |
| * correspond to dequant values of |
| * 2.5, 2.8125, 3.125, 3.5625, 3.9375, 4.4375. |
| * (a=0.5 b=sqrt(2/5) - refer to JVT-B038.doc) |
| * |
| * Assuming that h264Qp=12 corresponds to MPEG2 qscale of 2 |
| * (the actual mapping seems to be to MPEG2 qscale of 2.5), |
| * and the fact that the effective h264 quantizer changes by |
| * a factor of 2 for every 6 steps, the following mapping is |
| * obtained: |
| * h264qp = 6*(log2(mpeg2qscale/2)) + 12. |
| * |
| * Note that the quant matrix entry assumed for the above |
| * equality is 16. Hence when the mpeg2 quant matrix entries |
| * are all 16, this lookup can be used as is (which is the |
| * default inter quant matrix in mpeg-2). |
| ****************************************************************************** |
| */ |
| extern const UWORD8 gau1_mpeg2_to_h264_qmap[MPEG2_QP_ELEM]; |
| |
| |
| #endif /* IH264E_GLOBALS_H_ */ |
