/****************************************************************************** * * 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_ */