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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* EVC decoder/parser shared code
*/
#ifndef AVCODEC_EVC_PARSE_H
#define AVCODEC_EVC_PARSE_H
#include <stdint.h>
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "libavutil/rational.h"
#include "evc.h"
#include "evc_ps.h"
// The sturcture reflects Slice Header RBSP(raw byte sequence payload) layout
// @see ISO_IEC_23094-1 section 7.3.2.6
//
// The following descriptors specify the parsing process of each element
// u(n) - unsigned integer using n bits
// ue(v) - unsigned integer 0-th order Exp_Golomb-coded syntax element with the left bit first
// u(n) - unsigned integer using n bits.
// When n is "v" in the syntax table, the number of bits varies in a manner dependent on the value of other syntax elements.
typedef struct EVCParserSliceHeader {
int slice_pic_parameter_set_id; // ue(v)
int single_tile_in_slice_flag; // u(1)
int first_tile_id; // u(v)
int arbitrary_slice_flag; // u(1)
int last_tile_id; // u(v)
int num_remaining_tiles_in_slice_minus1; // ue(v)
int delta_tile_id_minus1[EVC_MAX_TILE_ROWS * EVC_MAX_TILE_COLUMNS]; // ue(v)
int slice_type; // ue(v)
int no_output_of_prior_pics_flag; // u(1)
int mmvd_group_enable_flag; // u(1)
int slice_alf_enabled_flag; // u(1)
int slice_alf_luma_aps_id; // u(5)
int slice_alf_map_flag; // u(1)
int slice_alf_chroma_idc; // u(2)
int slice_alf_chroma_aps_id; // u(5)
int slice_alf_chroma_map_flag; // u(1)
int slice_alf_chroma2_aps_id; // u(5)
int slice_alf_chroma2_map_flag; // u(1)
int slice_pic_order_cnt_lsb; // u(v)
// @note
// Currently the structure does not reflect the entire Slice Header RBSP layout.
// It contains only the fields that are necessary to read from the NAL unit all the values
// necessary for the correct initialization of the AVCodecContext structure.
// @note
// If necessary, add the missing fields to the structure to reflect
// the contents of the entire NAL unit of the SPS type
} EVCParserSliceHeader;
// picture order count of the current picture
typedef struct EVCParserPoc {
int PicOrderCntVal; // current picture order count value
int prevPicOrderCntVal; // the picture order count of the previous Tid0 picture
int DocOffset; // the decoding order count of the previous picture
} EVCParserPoc;
static inline int evc_get_nalu_type(const uint8_t *bits, int bits_size, void *logctx)
{
int unit_type_plus1 = 0;
if (bits_size >= EVC_NALU_HEADER_SIZE) {
unsigned char *p = (unsigned char *)bits;
// forbidden_zero_bit
if ((p[0] & 0x80) != 0) {
av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit header\n");
return -1;
}
// nal_unit_type
unit_type_plus1 = (p[0] >> 1) & 0x3F;
}
return unit_type_plus1 - 1;
}
static inline uint32_t evc_read_nal_unit_length(const uint8_t *bits, int bits_size, void *logctx)
{
uint32_t nalu_len = 0;
if (bits_size < EVC_NALU_LENGTH_PREFIX_SIZE) {
av_log(logctx, AV_LOG_ERROR, "Can't read NAL unit length\n");
return 0;
}
nalu_len = AV_RB32(bits);
return nalu_len;
}
// nuh_temporal_id specifies a temporal identifier for the NAL unit
int ff_evc_get_temporal_id(const uint8_t *bits, int bits_size, void *logctx);
int ff_evc_parse_slice_header(EVCParserSliceHeader *sh, const EVCParamSets *ps,
enum EVCNALUnitType nalu_type, const uint8_t *buf, int buf_size);
// POC (picture order count of the current picture) derivation
// @see ISO/IEC 23094-1:2020(E) 8.3.1 Decoding process for picture order count
int ff_evc_derive_poc(const EVCParamSets *ps, const EVCParserSliceHeader *sh,
EVCParserPoc *poc, enum EVCNALUnitType nalu_type, int tid);
#endif /* AVCODEC_EVC_PARSE_H */
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