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