[FFmpeg-devel] [PATCH v18 02/10] avcodec/evc_parser: Added parser implementation for EVC format

Dawid Kozinski d.kozinski at samsung.com
Tue Mar 28 16:46:36 EEST 2023


- Added constants definitions for EVC parser
- Provided NAL units parsing following ISO_IEC_23094-1
- EVC parser registration

Signed-off-by: Dawid Kozinski <d.kozinski at samsung.com>
---
 libavcodec/Makefile     |    1 +
 libavcodec/evc.h        |  155 +++++
 libavcodec/evc_parser.c | 1270 +++++++++++++++++++++++++++++++++++++++
 libavcodec/parsers.c    |    1 +
 4 files changed, 1427 insertions(+)
 create mode 100644 libavcodec/evc.h
 create mode 100644 libavcodec/evc_parser.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 408ecd1e31..635b936cac 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1157,6 +1157,7 @@ OBJS-$(CONFIG_DVAUDIO_PARSER)          += dvaudio_parser.o
 OBJS-$(CONFIG_DVBSUB_PARSER)           += dvbsub_parser.o
 OBJS-$(CONFIG_DVD_NAV_PARSER)          += dvd_nav_parser.o
 OBJS-$(CONFIG_DVDSUB_PARSER)           += dvdsub_parser.o
+OBJS-$(CONFIG_EVC_PARSER)              += evc_parser.o
 OBJS-$(CONFIG_FLAC_PARSER)             += flac_parser.o flacdata.o flac.o
 OBJS-$(CONFIG_FTR_PARSER)              += ftr_parser.o
 OBJS-$(CONFIG_G723_1_PARSER)           += g723_1_parser.o
diff --git a/libavcodec/evc.h b/libavcodec/evc.h
new file mode 100644
index 0000000000..d1fdb4fac6
--- /dev/null
+++ b/libavcodec/evc.h
@@ -0,0 +1,155 @@
+/*
+ * EVC definitions and enums
+ * Copyright (c) 2022 Dawid Kozinski <d.kozinski at samsung.com>
+ *
+ * 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
+ */
+
+#ifndef AVCODEC_EVC_H
+#define AVCODEC_EVC_H
+
+// The length field that indicates the length in bytes of the following NAL unit is configured to be of 4 bytes
+#define EVC_NALU_LENGTH_PREFIX_SIZE     (4)  /* byte */
+#define EVC_NALU_HEADER_SIZE            (2)  /* byte */
+
+/**
+ * @see ISO_IEC_23094-1_2020, 7.4.2.2 NAL unit header semantic
+ *      Table 4 - NAL unit type codes and NAL unit type classes
+ */
+enum EVCNALUnitType {
+    EVC_NOIDR_NUT            = 0,   /* Coded slice of a non-IDR picture */
+    EVC_IDR_NUT              = 1,   /* Coded slice of an IDR picture */
+    EVC_RSV_VCL_NUT02        = 2,
+    EVC_RSV_VCL_NUT03        = 3,
+    EVC_RSV_VCL_NUT04        = 4,
+    EVC_RSV_VCL_NUT05        = 5,
+    EVC_RSV_VCL_NUT06        = 6,
+    EVC_RSV_VCL_NUT07        = 7,
+    EVC_RSV_VCL_NUT08        = 8,
+    EVC_RSV_VCL_NUT09        = 9,
+    EVC_RSV_VCL_NUT10        = 10,
+    EVC_RSV_VCL_NUT11        = 11,
+    EVC_RSV_VCL_NUT12        = 12,
+    EVC_RSV_VCL_NUT13        = 13,
+    EVC_RSV_VCL_NUT14        = 14,
+    EVC_RSV_VCL_NUT15        = 15,
+    EVC_RSV_VCL_NUT16        = 16,
+    EVC_RSV_VCL_NUT17        = 17,
+    EVC_RSV_VCL_NUT18        = 18,
+    EVC_RSV_VCL_NUT19        = 19,
+    EVC_RSV_VCL_NUT20        = 20,
+    EVC_RSV_VCL_NUT21        = 21,
+    EVC_RSV_VCL_NUT22        = 22,
+    EVC_RSV_VCL_NUT23        = 23,
+    EVC_SPS_NUT              = 24,  /* Sequence parameter set */
+    EVC_PPS_NUT              = 25,  /* Picture paremeter set */
+    EVC_APS_NUT              = 26,  /* Adaptation parameter set */
+    EVC_FD_NUT               = 27,  /* Filler data */
+    EVC_SEI_NUT              = 28,  /* Supplemental enhancement information */
+    EVC_RSV_NONVCL29         = 29,
+    EVC_RSV_NONVCL30         = 30,
+    EVC_RSV_NONVCL31         = 31,
+    EVC_RSV_NONVCL32         = 32,
+    EVC_RSV_NONVCL33         = 33,
+    EVC_RSV_NONVCL34         = 34,
+    EVC_RSV_NONVCL35         = 35,
+    EVC_RSV_NONVCL36         = 36,
+    EVC_RSV_NONVCL37         = 37,
+    EVC_RSV_NONVCL38         = 38,
+    EVC_RSV_NONVCL39         = 39,
+    EVC_RSV_NONVCL40         = 40,
+    EVC_RSV_NONVCL41         = 41,
+    EVC_RSV_NONVCL42         = 42,
+    EVC_RSV_NONVCL43         = 43,
+    EVC_RSV_NONVCL44         = 44,
+    EVC_RSV_NONVCL45         = 45,
+    EVC_RSV_NONVCL46         = 46,
+    EVC_RSV_NONVCL47         = 47,
+    EVC_RSV_NONVCL48         = 48,
+    EVC_RSV_NONVCL49         = 49,
+    EVC_RSV_NONVCL50         = 50,
+    EVC_RSV_NONVCL51         = 51,
+    EVC_RSV_NONVCL52         = 52,
+    EVC_RSV_NONVCL53         = 53,
+    EVC_RSV_NONVCL54         = 54,
+    EVC_RSV_NONVCL55         = 55,
+    EVC_UNSPEC_NUT56         = 56,
+    EVC_UNSPEC_NUT57         = 57,
+    EVC_UNSPEC_NUT58         = 58,
+    EVC_UNSPEC_NUT59         = 59,
+    EVC_UNSPEC_NUT60         = 60,
+    EVC_UNSPEC_NUT61         = 61,
+    EVC_UNSPEC_NUT62         = 62
+};
+
+// slice type
+// @see ISO_IEC_23094-1_2020 7.4.5 Slice header semantics
+//
+enum EVCSliceType {
+    EVC_SLICE_TYPE_B = 0,
+    EVC_SLICE_TYPE_P = 1,
+    EVC_SLICE_TYPE_I = 2
+};
+
+enum {
+    // 7.4.3.2: aps_video_parameter_set_id is u(4).
+    EVC_MAX_APS_COUNT = 32,
+
+    // 7.4.3.1: sps_seq_parameter_set_id is in [0, 15].
+    EVC_MAX_SPS_COUNT = 16,
+
+    // 7.4.3.2: pps_pic_parameter_set_id is in [0, 63].
+    EVC_MAX_PPS_COUNT = 64,
+
+    // 7.4.5: slice header slice_pic_parameter_set_id in [0, 63]
+    EVC_MAX_SH_COUNT = 64,
+
+    // E.3.2: cpb_cnt_minus1[i] is in [0, 31].
+    EVC_MAX_CPB_CNT = 32,
+
+    // A.4.1: in table A.1 the highest level allows a MaxLumaPs of 35 651 584.
+    EVC_MAX_LUMA_PS = 35651584,
+
+    EVC_MAX_NUM_REF_PICS = 21,
+
+    EVC_MAX_NUM_RPLS = 32,
+
+    // A.4.1: pic_width_in_luma_samples and pic_height_in_luma_samples are
+    // constrained to be not greater than sqrt(MaxLumaPs * 8).  Hence height/
+    // width are bounded above by sqrt(8 * 35651584) = 16888.2 samples.
+    EVC_MAX_WIDTH  = 16888,
+    EVC_MAX_HEIGHT = 16888,
+
+    // A.4.1: table A.1 allows at most 22 tile rows for any level.
+    EVC_MAX_TILE_ROWS    = 22,
+    // A.4.1: table A.1 allows at most 20 tile columns for any level.
+    EVC_MAX_TILE_COLUMNS = 20,
+
+    // A.4.1: table A.1 allows at most 600 slice segments for any level.
+    EVC_MAX_SLICE_SEGMENTS = 600,
+
+    // 7.4.7.1: in the worst case (tiles_enabled_flag and
+    // entropy_coding_sync_enabled_flag are both set), entry points can be
+    // placed at the beginning of every Ctb row in every tile, giving an
+    // upper bound of (num_tile_columns_minus1 + 1) * PicHeightInCtbsY - 1.
+    // Only a stream with very high resolution and perverse parameters could
+    // get near that, though, so set a lower limit here with the maximum
+    // possible value for 4K video (at most 135 16x16 Ctb rows).
+    HEVC_MAX_ENTRY_POINT_OFFSETS = EVC_MAX_TILE_COLUMNS * 135,
+};
+
+#endif // AVCODEC_EVC_H
diff --git a/libavcodec/evc_parser.c b/libavcodec/evc_parser.c
new file mode 100644
index 0000000000..d27f33a637
--- /dev/null
+++ b/libavcodec/evc_parser.c
@@ -0,0 +1,1270 @@
+/*
+ * EVC format parser
+ *
+ * Copyright (C) 2021 Dawid Kozinski <d.kozinski at samsung.com>
+ *
+ * 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
+ */
+
+#include <stdint.h>
+
+#include "libavutil/common.h"
+#include "parser.h"
+#include "golomb.h"
+#include "evc.h"
+
+#define EVC_MAX_QP_TABLE_SIZE   58
+
+#define EXTENDED_SAR            255
+#define NUM_CPB                 32
+
+// rpl structure
+typedef struct RefPicListStruct {
+    int poc;
+    int tid;
+    int ref_pic_num;
+    int ref_pic_active_num;
+    int ref_pics[EVC_MAX_NUM_REF_PICS];
+    char pic_type;
+
+} RefPicListStruct;
+
+// chromaQP table structure to be signalled in SPS
+typedef struct ChromaQpTable {
+    int chroma_qp_table_present_flag;       // u(1)
+    int same_qp_table_for_chroma;           // u(1)
+    int global_offset_flag;                 // u(1)
+    int num_points_in_qp_table_minus1[2];   // ue(v)
+    int delta_qp_in_val_minus1[2][EVC_MAX_QP_TABLE_SIZE];   // u(6)
+    int delta_qp_out_val[2][EVC_MAX_QP_TABLE_SIZE];         // se(v)
+} ChromaQpTable;
+
+// Hypothetical Reference Decoder (HRD) parameters, part of VUI
+typedef struct HRDParameters {
+    int cpb_cnt_minus1;                             // ue(v)
+    int bit_rate_scale;                             // u(4)
+    int cpb_size_scale;                             // u(4)
+    int bit_rate_value_minus1[NUM_CPB];             // ue(v)
+    int cpb_size_value_minus1[NUM_CPB];             // ue(v)
+    int cbr_flag[NUM_CPB];                          // u(1)
+    int initial_cpb_removal_delay_length_minus1;    // u(5)
+    int cpb_removal_delay_length_minus1;            // u(5)
+    int dpb_output_delay_length_minus1;             // u(5)
+    int time_offset_length;                         // u(5)
+} HRDParameters;
+
+// video usability information (VUI) part of SPS
+typedef struct VUIParameters {
+    int aspect_ratio_info_present_flag;             // u(1)
+    int aspect_ratio_idc;                           // u(8)
+    int sar_width;                                  // u(16)
+    int sar_height;                                 // u(16)
+    int overscan_info_present_flag;                 // u(1)
+    int overscan_appropriate_flag;                  // u(1)
+    int video_signal_type_present_flag;             // u(1)
+    int video_format;                               // u(3)
+    int video_full_range_flag;                      // u(1)
+    int colour_description_present_flag;            // u(1)
+    int colour_primaries;                           // u(8)
+    int transfer_characteristics;                   // u(8)
+    int matrix_coefficients;                        // u(8)
+    int chroma_loc_info_present_flag;               // u(1)
+    int chroma_sample_loc_type_top_field;           // ue(v)
+    int chroma_sample_loc_type_bottom_field;        // ue(v)
+    int neutral_chroma_indication_flag;             // u(1)
+    int field_seq_flag;                             // u(1)
+    int timing_info_present_flag;                   // u(1)
+    int num_units_in_tick;                          // u(32)
+    int time_scale;                                 // u(32)
+    int fixed_pic_rate_flag;                        // u(1)
+    int nal_hrd_parameters_present_flag;            // u(1)
+    int vcl_hrd_parameters_present_flag;            // u(1)
+    int low_delay_hrd_flag;                         // u(1)
+    int pic_struct_present_flag;                    // u(1)
+    int bitstream_restriction_flag;                 // u(1)
+    int motion_vectors_over_pic_boundaries_flag;    // u(1)
+    int max_bytes_per_pic_denom;                    // ue(v)
+    int max_bits_per_mb_denom;                      // ue(v)
+    int log2_max_mv_length_horizontal;              // ue(v)
+    int log2_max_mv_length_vertical;                // ue(v)
+    int num_reorder_pics;                           // ue(v)
+    int max_dec_pic_buffering;                      // ue(v)
+
+    HRDParameters hrd_parameters;
+} VUIParameters;
+
+// The sturcture reflects SPS RBSP(raw byte sequence payload) layout
+// @see ISO_IEC_23094-1 section 7.3.2.1
+//
+// 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
+typedef struct EVCParserSPS {
+    int sps_seq_parameter_set_id;   // ue(v)
+    int profile_idc;                // u(8)
+    int level_idc;                  // u(8)
+    int toolset_idc_h;              // u(32)
+    int toolset_idc_l;              // u(32)
+    int chroma_format_idc;          // ue(v)
+    int pic_width_in_luma_samples;  // ue(v)
+    int pic_height_in_luma_samples; // ue(v)
+    int bit_depth_luma_minus8;      // ue(v)
+    int bit_depth_chroma_minus8;    // ue(v)
+
+    int sps_btt_flag;                           // u(1)
+    int log2_ctu_size_minus5;                   // ue(v)
+    int log2_min_cb_size_minus2;                // ue(v)
+    int log2_diff_ctu_max_14_cb_size;           // ue(v)
+    int log2_diff_ctu_max_tt_cb_size;           // ue(v)
+    int log2_diff_min_cb_min_tt_cb_size_minus2; // ue(v)
+
+    int sps_suco_flag;                       // u(1)
+    int log2_diff_ctu_size_max_suco_cb_size; // ue(v)
+    int log2_diff_max_suco_min_suco_cb_size; // ue(v)
+
+    int sps_admvp_flag;     // u(1)
+    int sps_affine_flag;    // u(1)
+    int sps_amvr_flag;      // u(1)
+    int sps_dmvr_flag;      // u(1)
+    int sps_mmvd_flag;      // u(1)
+    int sps_hmvp_flag;      // u(1)
+
+    int sps_eipd_flag;                 // u(1)
+    int sps_ibc_flag;                  // u(1)
+    int log2_max_ibc_cand_size_minus2; // ue(v)
+
+    int sps_cm_init_flag; // u(1)
+    int sps_adcc_flag;    // u(1)
+
+    int sps_iqt_flag; // u(1)
+    int sps_ats_flag; // u(1)
+
+    int sps_addb_flag;   // u(1)
+    int sps_alf_flag;    // u(1)
+    int sps_htdf_flag;   // u(1)
+    int sps_rpl_flag;    // u(1)
+    int sps_pocs_flag;   // u(1)
+    int sps_dquant_flag; // u(1)
+    int sps_dra_flag;    // u(1)
+
+    int log2_max_pic_order_cnt_lsb_minus4; // ue(v)
+    int log2_sub_gop_length;               // ue(v)
+    int log2_ref_pic_gap_length;           // ue(v)
+
+    int max_num_tid0_ref_pics; // ue(v)
+
+    int sps_max_dec_pic_buffering_minus1; // ue(v)
+    int long_term_ref_pic_flag;           // u(1)
+    int rpl1_same_as_rpl0_flag;           // u(1)
+    int num_ref_pic_list_in_sps[2];       // ue(v)
+    struct RefPicListStruct rpls[2][EVC_MAX_NUM_RPLS];
+
+    int picture_cropping_flag;      // u(1)
+    int picture_crop_left_offset;   // ue(v)
+    int picture_crop_right_offset;  // ue(v)
+    int picture_crop_top_offset;    // ue(v)
+    int picture_crop_bottom_offset; // ue(v)
+
+    struct ChromaQpTable chroma_qp_table_struct;
+
+    int vui_parameters_present_flag;    // u(1)
+
+    struct VUIParameters vui_parameters;
+
+} EVCParserSPS;
+
+typedef struct EVCParserPPS {
+    int pps_pic_parameter_set_id;                           // ue(v)
+    int pps_seq_parameter_set_id;                           // ue(v)
+    int num_ref_idx_default_active_minus1[2];               // ue(v)
+    int additional_lt_poc_lsb_len;                          // ue(v)
+    int rpl1_idx_present_flag;                              // u(1)
+    int single_tile_in_pic_flag;                            // u(1)
+    int num_tile_columns_minus1;                            // ue(v)
+    int num_tile_rows_minus1;                               // ue(v)
+    int uniform_tile_spacing_flag;                          // u(1)
+    int tile_column_width_minus1[EVC_MAX_TILE_ROWS];        // ue(v)
+    int tile_row_height_minus1[EVC_MAX_TILE_COLUMNS];          // ue(v)
+    int loop_filter_across_tiles_enabled_flag;              // u(1)
+    int tile_offset_len_minus1;                             // ue(v)
+    int tile_id_len_minus1;                                 // ue(v)
+    int explicit_tile_id_flag;                              // u(1)
+    int tile_id_val[EVC_MAX_TILE_ROWS][EVC_MAX_TILE_COLUMNS];  // u(v)
+    int pic_dra_enabled_flag;                               // u(1)
+    int pic_dra_aps_id;                                     // u(5)
+    int arbitrary_slice_present_flag;                       // u(1)
+    int constrained_intra_pred_flag;                        // u(1)
+    int cu_qp_delta_enabled_flag;                           // u(1)
+    int log2_cu_qp_delta_area_minus6;                       // ue(v)
+
+} EVCParserPPS;
+
+// 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;
+
+typedef struct EVCParserContext {
+    ParseContext pc;
+    EVCParserSPS sps[EVC_MAX_SPS_COUNT];
+    EVCParserPPS pps[EVC_MAX_PPS_COUNT];
+    EVCParserSliceHeader slice_header[EVC_MAX_PPS_COUNT];
+
+    int to_read;    // number of bytes of NAL Unit that do not fit into the current input data chunk and must be read from the new chunk(s)
+    int bytes_read; // number of bytes of the current Access Unit that already has been read
+
+    int incomplete_nalu_prefix_read; // the flag is set to 1 when the current input data chunk contains an incomplete NAL unit prefix
+    int incomplete_nalu_read;        // the flag is set to 1 when the current input data chunk contains an incomplete NAL unit (more input data is needed to read complete NAL unit)
+
+    int nuh_temporal_id;            // the value of TemporalId (shall be the same for all VCL NAL units of an Access Unit)
+
+    int nalu_prefix_assembled;      // the flag is set to when NALU prefix has been assembled from last chunk and current chunk of incoming data
+    int nalu_type;                  // the current NALU type
+    int nalu_size;                  // the current NALU size
+    int time_base;
+
+    EVCParserPoc poc;
+
+    int parsed_extradata;
+
+} EVCParserContext;
+
+static int get_nalu_type(const uint8_t *bits, int bits_size, AVCodecContext *avctx)
+{
+    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)
+            return -1;
+
+        // nal_unit_type
+        unit_type_plus1 = (p[0] >> 1) & 0x3F;
+    }
+
+    return unit_type_plus1 - 1;
+}
+
+static uint32_t read_nal_unit_length(const uint8_t *bits, int bits_size, AVCodecContext *avctx)
+{
+    uint32_t nalu_len = 0;
+
+    if (bits_size >= EVC_NALU_LENGTH_PREFIX_SIZE) {
+
+        int t = 0;
+        unsigned char *p = (unsigned char *)bits;
+
+        for (int i = 0; i < EVC_NALU_LENGTH_PREFIX_SIZE; i++)
+            t = (t << 8) | p[i];
+
+        nalu_len = t;
+        if (nalu_len == 0)
+            return 0;
+    }
+
+    return nalu_len;
+}
+
+// nuh_temporal_id specifies a temporal identifier for the NAL unit
+static int get_temporal_id(const uint8_t *bits, int bits_size, AVCodecContext *avctx)
+{
+    int temporal_id = 0;
+    short t = 0;
+
+    if (bits_size >= EVC_NALU_HEADER_SIZE) {
+        unsigned char *p = (unsigned char *)bits;
+        // forbidden_zero_bit
+        if ((p[0] & 0x80) != 0)
+            return -1;
+
+        for (int i = 0; i < EVC_NALU_HEADER_SIZE; i++)
+            t = (t << 8) | p[i];
+
+        temporal_id = (t >> 6) & 0x0007;
+    }
+
+    return temporal_id;
+}
+
+// @see ISO_IEC_23094-1 (7.3.7 Reference picture list structure syntax)
+static int ref_pic_list_struct(GetBitContext *gb, RefPicListStruct *rpl)
+{
+    uint32_t delta_poc_st, strp_entry_sign_flag = 0;
+    rpl->ref_pic_num = get_ue_golomb(gb);
+    if (rpl->ref_pic_num > 0) {
+        delta_poc_st = get_ue_golomb(gb);
+
+        rpl->ref_pics[0] = delta_poc_st;
+        if (rpl->ref_pics[0] != 0) {
+            strp_entry_sign_flag = get_bits(gb, 1);
+
+            rpl->ref_pics[0] *= 1 - (strp_entry_sign_flag << 1);
+        }
+    }
+
+    for (int i = 1; i < rpl->ref_pic_num; ++i) {
+        delta_poc_st = get_ue_golomb(gb);
+        if (delta_poc_st != 0)
+            strp_entry_sign_flag = get_bits(gb, 1);
+        rpl->ref_pics[i] = rpl->ref_pics[i - 1] + delta_poc_st * (1 - (strp_entry_sign_flag << 1));
+    }
+
+    return 0;
+}
+
+// @see  ISO_IEC_23094-1 (E.2.2 HRD parameters syntax)
+static int hrd_parameters(GetBitContext *gb, HRDParameters *hrd)
+{
+    hrd->cpb_cnt_minus1 = get_ue_golomb(gb);
+    hrd->bit_rate_scale = get_bits(gb, 4);
+    hrd->cpb_size_scale = get_bits(gb, 4);
+    for (int SchedSelIdx = 0; SchedSelIdx <= hrd->cpb_cnt_minus1; SchedSelIdx++) {
+        hrd->bit_rate_value_minus1[SchedSelIdx] = get_ue_golomb(gb);
+        hrd->cpb_size_value_minus1[SchedSelIdx] = get_ue_golomb(gb);
+        hrd->cbr_flag[SchedSelIdx] = get_bits(gb, 1);
+    }
+    hrd->initial_cpb_removal_delay_length_minus1 = get_bits(gb, 5);
+    hrd->cpb_removal_delay_length_minus1 = get_bits(gb, 5);
+    hrd->cpb_removal_delay_length_minus1 = get_bits(gb, 5);
+    hrd->time_offset_length = get_bits(gb, 5);
+
+    return 0;
+}
+
+// @see  ISO_IEC_23094-1 (E.2.1 VUI parameters syntax)
+static int vui_parameters(GetBitContext *gb, VUIParameters *vui)
+{
+    vui->aspect_ratio_info_present_flag = get_bits(gb, 1);
+    if (vui->aspect_ratio_info_present_flag) {
+        vui->aspect_ratio_idc = get_bits(gb, 8);
+        if (vui->aspect_ratio_idc == EXTENDED_SAR) {
+            vui->sar_width = get_bits(gb, 16);
+            vui->sar_height = get_bits(gb, 16);
+        }
+    }
+    vui->overscan_info_present_flag = get_bits(gb, 1);
+    if (vui->overscan_info_present_flag)
+        vui->overscan_appropriate_flag = get_bits(gb, 1);
+    vui->video_signal_type_present_flag = get_bits(gb, 1);
+    if (vui->video_signal_type_present_flag) {
+        vui->video_format = get_bits(gb, 3);
+        vui->video_full_range_flag = get_bits(gb, 1);
+        vui->colour_description_present_flag = get_bits(gb, 1);
+        if (vui->colour_description_present_flag) {
+            vui->colour_primaries = get_bits(gb, 8);
+            vui->transfer_characteristics = get_bits(gb, 8);
+            vui->matrix_coefficients = get_bits(gb, 8);
+        }
+    }
+    vui->chroma_loc_info_present_flag = get_bits(gb, 1);
+    if (vui->chroma_loc_info_present_flag) {
+        vui->chroma_sample_loc_type_top_field = get_ue_golomb(gb);
+        vui->chroma_sample_loc_type_bottom_field = get_ue_golomb(gb);
+    }
+    vui->neutral_chroma_indication_flag = get_bits(gb, 1);
+
+    vui->field_seq_flag = get_bits(gb, 1);
+
+    vui->timing_info_present_flag = get_bits(gb, 1);
+    if (vui->timing_info_present_flag) {
+        vui->num_units_in_tick = get_bits(gb, 32);
+        vui->time_scale = get_bits(gb, 32);
+        vui->fixed_pic_rate_flag = get_bits(gb, 1);
+    }
+    vui->nal_hrd_parameters_present_flag = get_bits(gb, 1);
+    if (vui->nal_hrd_parameters_present_flag)
+        hrd_parameters(gb, &vui->hrd_parameters);
+    vui->vcl_hrd_parameters_present_flag = get_bits(gb, 1);
+    if (vui->vcl_hrd_parameters_present_flag)
+        hrd_parameters(gb, &vui->hrd_parameters);
+    if (vui->nal_hrd_parameters_present_flag || vui->vcl_hrd_parameters_present_flag)
+        vui->low_delay_hrd_flag = get_bits(gb, 1);
+    vui->pic_struct_present_flag = get_bits(gb, 1);
+    vui->bitstream_restriction_flag = get_bits(gb, 1);
+    if (vui->bitstream_restriction_flag) {
+        vui->motion_vectors_over_pic_boundaries_flag = get_bits(gb, 1);
+        vui->max_bytes_per_pic_denom = get_ue_golomb(gb);
+        vui->max_bits_per_mb_denom = get_ue_golomb(gb);
+        vui->log2_max_mv_length_horizontal = get_ue_golomb(gb);
+        vui->log2_max_mv_length_vertical = get_ue_golomb(gb);
+        vui->num_reorder_pics = get_ue_golomb(gb);
+        vui->max_dec_pic_buffering = get_ue_golomb(gb);
+    }
+
+    return 0;
+}
+
+// @see ISO_IEC_23094-1 (7.3.2.1 SPS RBSP syntax)
+static EVCParserSPS *parse_sps(const uint8_t *bs, int bs_size, EVCParserContext *ev)
+{
+    GetBitContext gb;
+    EVCParserSPS *sps;
+    int sps_seq_parameter_set_id;
+
+    if (init_get_bits8(&gb, bs, bs_size) < 0)
+        return NULL;
+
+    sps_seq_parameter_set_id = get_ue_golomb(&gb);
+
+    if (sps_seq_parameter_set_id >= EVC_MAX_SPS_COUNT)
+        return NULL;
+
+    sps = &ev->sps[sps_seq_parameter_set_id];
+    sps->sps_seq_parameter_set_id = sps_seq_parameter_set_id;
+
+    // the Baseline profile is indicated by profile_idc eqal to 0
+    // the Main profile is indicated by profile_idc eqal to 1
+    sps->profile_idc = get_bits(&gb, 8);
+
+    sps->level_idc = get_bits(&gb, 8);
+
+    skip_bits_long(&gb, 32); /* skip toolset_idc_h */
+    skip_bits_long(&gb, 32); /* skip toolset_idc_l */
+
+    // 0 - monochrome
+    // 1 - 4:2:0
+    // 2 - 4:2:2
+    // 3 - 4:4:4
+    sps->chroma_format_idc = get_ue_golomb(&gb);
+
+    sps->pic_width_in_luma_samples = get_ue_golomb(&gb);
+    sps->pic_height_in_luma_samples = get_ue_golomb(&gb);
+
+    sps->bit_depth_luma_minus8 = get_ue_golomb(&gb);
+    sps->bit_depth_chroma_minus8 = get_ue_golomb(&gb);
+
+    sps->sps_btt_flag = get_bits(&gb, 1);
+    if (sps->sps_btt_flag) {
+        sps->log2_ctu_size_minus5 = get_ue_golomb(&gb);
+        sps->log2_min_cb_size_minus2 = get_ue_golomb(&gb);
+        sps->log2_diff_ctu_max_14_cb_size = get_ue_golomb(&gb);
+        sps->log2_diff_ctu_max_tt_cb_size = get_ue_golomb(&gb);
+        sps->log2_diff_min_cb_min_tt_cb_size_minus2 = get_ue_golomb(&gb);
+    }
+
+    sps->sps_suco_flag = get_bits(&gb, 1);
+    if (sps->sps_suco_flag) {
+        sps->log2_diff_ctu_size_max_suco_cb_size = get_ue_golomb(&gb);
+        sps->log2_diff_max_suco_min_suco_cb_size = get_ue_golomb(&gb);
+    }
+
+    sps->sps_admvp_flag = get_bits(&gb, 1);
+    if (sps->sps_admvp_flag) {
+        sps->sps_affine_flag = get_bits(&gb, 1);
+        sps->sps_amvr_flag = get_bits(&gb, 1);
+        sps->sps_dmvr_flag = get_bits(&gb, 1);
+        sps->sps_mmvd_flag = get_bits(&gb, 1);
+        sps->sps_hmvp_flag = get_bits(&gb, 1);
+    }
+
+    sps->sps_eipd_flag =  get_bits(&gb, 1);
+    if (sps->sps_eipd_flag) {
+        sps->sps_ibc_flag = get_bits(&gb, 1);
+        if (sps->sps_ibc_flag)
+            sps->log2_max_ibc_cand_size_minus2 = get_ue_golomb(&gb);
+    }
+
+    sps->sps_cm_init_flag = get_bits(&gb, 1);
+    if (sps->sps_cm_init_flag)
+        sps->sps_adcc_flag = get_bits(&gb, 1);
+
+    sps->sps_iqt_flag = get_bits(&gb, 1);
+    if (sps->sps_iqt_flag)
+        sps->sps_ats_flag = get_bits(&gb, 1);
+
+    sps->sps_addb_flag = get_bits(&gb, 1);
+    sps->sps_alf_flag = get_bits(&gb, 1);
+    sps->sps_htdf_flag = get_bits(&gb, 1);
+    sps->sps_rpl_flag = get_bits(&gb, 1);
+    sps->sps_pocs_flag = get_bits(&gb, 1);
+    sps->sps_dquant_flag = get_bits(&gb, 1);
+    sps->sps_dra_flag = get_bits(&gb, 1);
+
+    if (sps->sps_pocs_flag)
+        sps->log2_max_pic_order_cnt_lsb_minus4 = get_ue_golomb(&gb);
+
+    if (!sps->sps_pocs_flag || !sps->sps_rpl_flag) {
+        sps->log2_sub_gop_length = get_ue_golomb(&gb);
+        if (sps->log2_sub_gop_length == 0)
+            sps->log2_ref_pic_gap_length = get_ue_golomb(&gb);
+    }
+
+    if (!sps->sps_rpl_flag)
+        sps->max_num_tid0_ref_pics = get_ue_golomb(&gb);
+    else {
+        sps->sps_max_dec_pic_buffering_minus1 = get_ue_golomb(&gb);
+        sps->long_term_ref_pic_flag = get_bits(&gb, 1);
+        sps->rpl1_same_as_rpl0_flag = get_bits(&gb, 1);
+        sps->num_ref_pic_list_in_sps[0] = get_ue_golomb(&gb);
+
+        for (int i = 0; i < sps->num_ref_pic_list_in_sps[0]; ++i)
+            ref_pic_list_struct(&gb, &sps->rpls[0][i]);
+
+        if (!sps->rpl1_same_as_rpl0_flag) {
+            sps->num_ref_pic_list_in_sps[1] = get_ue_golomb(&gb);
+            for (int i = 0; i < sps->num_ref_pic_list_in_sps[1]; ++i)
+                ref_pic_list_struct(&gb, &sps->rpls[1][i]);
+        }
+    }
+
+    sps->picture_cropping_flag = get_bits(&gb, 1);
+
+    if (sps->picture_cropping_flag) {
+        sps->picture_crop_left_offset = get_ue_golomb(&gb);
+        sps->picture_crop_right_offset = get_ue_golomb(&gb);
+        sps->picture_crop_top_offset = get_ue_golomb(&gb);
+        sps->picture_crop_bottom_offset = get_ue_golomb(&gb);
+    }
+
+    if (sps->chroma_format_idc != 0) {
+        sps->chroma_qp_table_struct.chroma_qp_table_present_flag = get_bits(&gb, 1);
+
+        if (sps->chroma_qp_table_struct.chroma_qp_table_present_flag) {
+            sps->chroma_qp_table_struct.same_qp_table_for_chroma = get_bits(&gb, 1);
+            sps->chroma_qp_table_struct.global_offset_flag = get_bits(&gb, 1);
+            for (int i = 0; i < (sps->chroma_qp_table_struct.same_qp_table_for_chroma ? 1 : 2); i++) {
+                sps->chroma_qp_table_struct.num_points_in_qp_table_minus1[i] = get_ue_golomb(&gb);;
+                for (int j = 0; j <= sps->chroma_qp_table_struct.num_points_in_qp_table_minus1[i]; j++) {
+                    sps->chroma_qp_table_struct.delta_qp_in_val_minus1[i][j] = get_bits(&gb, 6);
+                    sps->chroma_qp_table_struct.delta_qp_out_val[i][j] = get_se_golomb(&gb);
+                }
+            }
+        }
+    }
+
+    sps->vui_parameters_present_flag = get_bits(&gb, 1);
+    if (sps->vui_parameters_present_flag)
+        vui_parameters(&gb, &(sps->vui_parameters));
+
+    // @note
+    // If necessary, add the missing fields to the EVCParserSPS structure
+    // and then extend parser implementation
+
+    return sps;
+}
+
+// @see ISO_IEC_23094-1 (7.3.2.2 SPS RBSP syntax)
+//
+// @note
+// The current implementation of parse_sps function doesn't handle VUI parameters parsing.
+// If it will be needed, parse_sps function could be extended to handle VUI parameters parsing
+// to initialize fields of the AVCodecContex i.e. color_primaries, color_trc,color_range
+//
+static EVCParserPPS *parse_pps(const uint8_t *bs, int bs_size, EVCParserContext *ev)
+{
+    GetBitContext gb;
+    EVCParserPPS *pps;
+
+    int pps_pic_parameter_set_id;
+
+    if (init_get_bits8(&gb, bs, bs_size) < 0)
+        return NULL;
+
+    pps_pic_parameter_set_id = get_ue_golomb(&gb);
+    if (pps_pic_parameter_set_id > EVC_MAX_PPS_COUNT)
+        return NULL;
+
+    pps = &ev->pps[pps_pic_parameter_set_id];
+
+    pps->pps_pic_parameter_set_id = pps_pic_parameter_set_id;
+
+    pps->pps_seq_parameter_set_id = get_ue_golomb(&gb);
+    if (pps->pps_seq_parameter_set_id >= EVC_MAX_SPS_COUNT)
+        return NULL;
+
+    pps->num_ref_idx_default_active_minus1[0] = get_ue_golomb(&gb);
+    pps->num_ref_idx_default_active_minus1[1] = get_ue_golomb(&gb);
+    pps->additional_lt_poc_lsb_len = get_ue_golomb(&gb);
+    pps->rpl1_idx_present_flag = get_bits(&gb, 1);
+    pps->single_tile_in_pic_flag = get_bits(&gb, 1);
+
+    if (!pps->single_tile_in_pic_flag) {
+        pps->num_tile_columns_minus1 = get_ue_golomb(&gb);
+        pps->num_tile_rows_minus1 = get_ue_golomb(&gb);
+        pps->uniform_tile_spacing_flag = get_bits(&gb, 1);
+
+        if (!pps->uniform_tile_spacing_flag) {
+            for (int i = 0; i < pps->num_tile_columns_minus1; i++)
+                pps->tile_column_width_minus1[i] = get_ue_golomb(&gb);
+
+            for (int i = 0; i < pps->num_tile_rows_minus1; i++)
+                pps->tile_row_height_minus1[i] = get_ue_golomb(&gb);
+        }
+        pps->loop_filter_across_tiles_enabled_flag = get_bits(&gb, 1);
+        pps->tile_offset_len_minus1 = get_ue_golomb(&gb);
+    }
+
+    pps->tile_id_len_minus1 = get_ue_golomb(&gb);
+    pps->explicit_tile_id_flag = get_bits(&gb, 1);
+
+    if (pps->explicit_tile_id_flag) {
+        for (int i = 0; i <= pps->num_tile_rows_minus1; i++) {
+            for (int j = 0; j <= pps->num_tile_columns_minus1; j++)
+                pps->tile_id_val[i][j] = get_bits(&gb, pps->tile_id_len_minus1 + 1);
+        }
+    }
+
+    pps->pic_dra_enabled_flag = 0;
+    pps->pic_dra_enabled_flag = get_bits(&gb, 1);
+
+    if (pps->pic_dra_enabled_flag)
+        pps->pic_dra_aps_id = get_bits(&gb, 5);
+
+    pps->arbitrary_slice_present_flag = get_bits(&gb, 1);
+    pps->constrained_intra_pred_flag = get_bits(&gb, 1);
+    pps->cu_qp_delta_enabled_flag = get_bits(&gb, 1);
+
+    if (pps->cu_qp_delta_enabled_flag)
+        pps->log2_cu_qp_delta_area_minus6 = get_ue_golomb(&gb);
+
+    return pps;
+}
+
+// @see ISO_IEC_23094-1 (7.3.2.6 Slice layer RBSP syntax)
+static EVCParserSliceHeader *parse_slice_header(const uint8_t *bs, int bs_size, EVCParserContext *ev)
+{
+    GetBitContext gb;
+    EVCParserSliceHeader *sh;
+    EVCParserPPS *pps;
+    EVCParserSPS *sps;
+
+    int num_tiles_in_slice = 0;
+    int slice_pic_parameter_set_id;
+
+    if (init_get_bits8(&gb, bs, bs_size) < 0)
+        return NULL;
+
+    slice_pic_parameter_set_id = get_ue_golomb(&gb);
+
+    if (slice_pic_parameter_set_id < 0 || slice_pic_parameter_set_id >= EVC_MAX_PPS_COUNT)
+        return NULL;
+
+    sh = &ev->slice_header[slice_pic_parameter_set_id];
+    pps = &ev->pps[slice_pic_parameter_set_id];
+    sps = &ev->sps[slice_pic_parameter_set_id];
+
+    sh->slice_pic_parameter_set_id = slice_pic_parameter_set_id;
+
+    if (!pps->single_tile_in_pic_flag) {
+        sh->single_tile_in_slice_flag = get_bits(&gb, 1);
+        sh->first_tile_id = get_bits(&gb, pps->tile_id_len_minus1 + 1);
+    } else
+        sh->single_tile_in_slice_flag = 1;
+
+    if (!sh->single_tile_in_slice_flag) {
+        if (pps->arbitrary_slice_present_flag)
+            sh->arbitrary_slice_flag = get_bits(&gb, 1);
+
+        if (!sh->arbitrary_slice_flag)
+            sh->last_tile_id = get_bits(&gb, pps->tile_id_len_minus1 + 1);
+        else {
+            sh->num_remaining_tiles_in_slice_minus1 = get_ue_golomb(&gb);
+            num_tiles_in_slice = sh->num_remaining_tiles_in_slice_minus1 + 2;
+            for (int i = 0; i < num_tiles_in_slice - 1; ++i)
+                sh->delta_tile_id_minus1[i] = get_ue_golomb(&gb);
+        }
+    }
+
+    sh->slice_type = get_ue_golomb(&gb);
+
+    if (ev->nalu_type == EVC_IDR_NUT)
+        sh->no_output_of_prior_pics_flag = get_bits(&gb, 1);
+
+    if (sps->sps_mmvd_flag && ((sh->slice_type == EVC_SLICE_TYPE_B) || (sh->slice_type == EVC_SLICE_TYPE_P)))
+        sh->mmvd_group_enable_flag = get_bits(&gb, 1);
+    else
+        sh->mmvd_group_enable_flag = 0;
+
+    if (sps->sps_alf_flag) {
+        int ChromaArrayType = sps->chroma_format_idc;
+
+        sh->slice_alf_enabled_flag = get_bits(&gb, 1);
+
+        if (sh->slice_alf_enabled_flag) {
+            sh->slice_alf_luma_aps_id = get_bits(&gb, 5);
+            sh->slice_alf_map_flag = get_bits(&gb, 1);
+            sh->slice_alf_chroma_idc = get_bits(&gb, 2);
+
+            if ((ChromaArrayType == 1 || ChromaArrayType == 2) && sh->slice_alf_chroma_idc > 0)
+                sh->slice_alf_chroma_aps_id =  get_bits(&gb, 5);
+        }
+        if (ChromaArrayType == 3) {
+            int sliceChromaAlfEnabledFlag = 0;
+            int sliceChroma2AlfEnabledFlag = 0;
+
+            if (sh->slice_alf_chroma_idc == 1) { // @see ISO_IEC_23094-1 (7.4.5)
+                sliceChromaAlfEnabledFlag = 1;
+                sliceChroma2AlfEnabledFlag = 0;
+            } else if (sh->slice_alf_chroma_idc == 2) {
+                sliceChromaAlfEnabledFlag = 0;
+                sliceChroma2AlfEnabledFlag = 1;
+            } else if (sh->slice_alf_chroma_idc == 3) {
+                sliceChromaAlfEnabledFlag = 1;
+                sliceChroma2AlfEnabledFlag = 1;
+            } else {
+                sliceChromaAlfEnabledFlag = 0;
+                sliceChroma2AlfEnabledFlag = 0;
+            }
+
+            if (!sh->slice_alf_enabled_flag)
+                sh->slice_alf_chroma_idc = get_bits(&gb, 2);
+
+            if (sliceChromaAlfEnabledFlag) {
+                sh->slice_alf_chroma_aps_id = get_bits(&gb, 5);
+                sh->slice_alf_chroma_map_flag = get_bits(&gb, 1);
+            }
+
+            if (sliceChroma2AlfEnabledFlag) {
+                sh->slice_alf_chroma2_aps_id = get_bits(&gb, 5);
+                sh->slice_alf_chroma2_map_flag = get_bits(&gb, 1);
+            }
+        }
+    }
+
+    if (ev->nalu_type != EVC_IDR_NUT) {
+        if (sps->sps_pocs_flag)
+            sh->slice_pic_order_cnt_lsb = get_bits(&gb, sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
+    }
+
+    // @note
+    // If necessary, add the missing fields to the EVCParserSliceHeader structure
+    // and then extend parser implementation
+
+    return sh;
+}
+
+static int parse_nal_unit(AVCodecParserContext *s, const uint8_t *buf,
+                          int buf_size, AVCodecContext *avctx)
+{
+    EVCParserContext *ev = s->priv_data;
+    int nalu_type, nalu_size;
+    int tid;
+    const uint8_t *data = buf;
+    int data_size = buf_size;
+
+    s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
+    s->key_frame = -1;
+
+
+    nalu_size = buf_size;
+    if (nalu_size <= 0) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid NAL unit size: (%d)\n", nalu_size);
+        return AVERROR_INVALIDDATA;
+    }
+
+    // @see ISO_IEC_23094-1_2020, 7.4.2.2 NAL unit header semantic (Table 4 - NAL unit type codes and NAL unit type classes)
+    // @see enum EVCNALUnitType in evc.h
+    nalu_type = get_nalu_type(data, data_size, avctx);
+    if (nalu_type < EVC_NOIDR_NUT || nalu_type > EVC_UNSPEC_NUT62) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid NAL unit type: (%d)\n", nalu_type);
+        return AVERROR_INVALIDDATA;
+    }
+    ev->nalu_type = nalu_type;
+
+    tid = get_temporal_id(data, data_size, avctx);
+    if (tid < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid temporial id: (%d)\n", tid);
+        return AVERROR_INVALIDDATA;
+    }
+    ev->nuh_temporal_id = tid;
+
+    if (data_size < nalu_size) {
+        av_log(avctx, AV_LOG_ERROR, "NAL unit does not fit in the data buffer\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    data += EVC_NALU_HEADER_SIZE;
+    data_size -= EVC_NALU_HEADER_SIZE;
+
+    if (nalu_type == EVC_SPS_NUT) {
+        EVCParserSPS *sps;
+        int SubGopLength;
+
+        sps = parse_sps(data, nalu_size, ev);
+        if (!sps) {
+            av_log(avctx, AV_LOG_ERROR, "SPS parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        s->coded_width         = sps->pic_width_in_luma_samples;
+        s->coded_height        = sps->pic_height_in_luma_samples;
+        s->width               = sps->pic_width_in_luma_samples  - sps->picture_crop_left_offset - sps->picture_crop_right_offset;
+        s->height              = sps->pic_height_in_luma_samples - sps->picture_crop_top_offset  - sps->picture_crop_bottom_offset;
+
+        SubGopLength = (int)pow(2.0, sps->log2_sub_gop_length);
+        avctx->gop_size = SubGopLength;
+
+        avctx->delay = (sps->sps_max_dec_pic_buffering_minus1) ? sps->sps_max_dec_pic_buffering_minus1 - 1 : SubGopLength + sps->max_num_tid0_ref_pics - 1;
+
+        if (sps->profile_idc == 1) avctx->profile = FF_PROFILE_EVC_MAIN;
+        else avctx->profile = FF_PROFILE_EVC_BASELINE;
+
+        ev->time_base = avctx->time_base.den;
+
+        switch (sps->chroma_format_idc) {
+        case 0: /* YCBCR400_10LE */
+            av_log(avctx, AV_LOG_ERROR, "YCBCR400_10LE: Not supported chroma format\n");
+            s->format = AV_PIX_FMT_GRAY10LE;
+            return -1;
+        case 1: /* YCBCR420_10LE */
+            s->format = AV_PIX_FMT_YUV420P10LE;
+            break;
+        case 2: /* YCBCR422_10LE */
+            av_log(avctx, AV_LOG_ERROR, "YCBCR422_10LE: Not supported chroma format\n");
+            s->format = AV_PIX_FMT_YUV422P10LE;
+            return -1;
+        case 3: /* YCBCR444_10LE */
+            av_log(avctx, AV_LOG_ERROR, "YCBCR444_10LE: Not supported chroma format\n");
+            s->format = AV_PIX_FMT_YUV444P10LE;
+            return -1;
+        default:
+            s->format = AV_PIX_FMT_NONE;
+            av_log(avctx, AV_LOG_ERROR, "Unknown supported chroma format\n");
+            return -1;
+        }
+    } else if (nalu_type == EVC_PPS_NUT) {
+        EVCParserPPS *pps;
+
+        pps = parse_pps(data, nalu_size, ev);
+        if (!pps) {
+            av_log(avctx, AV_LOG_ERROR, "PPS parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+    } else if (nalu_type == EVC_SEI_NUT)  // Supplemental Enhancement Information
+        return 0;
+    else if (nalu_type == EVC_APS_NUT)   // Adaptation parameter set
+        return 0;
+    else if (nalu_type == EVC_FD_NUT)   /* Filler data */
+        return 0;
+    else if (nalu_type == EVC_IDR_NUT || nalu_type == EVC_NOIDR_NUT) { // Coded slice of a IDR or non-IDR picture
+        EVCParserSliceHeader *sh;
+        EVCParserSPS *sps;
+        int slice_pic_parameter_set_id;
+
+        sh = parse_slice_header(data, nalu_size, ev);
+        if (!sh) {
+            av_log(avctx, AV_LOG_ERROR, "Slice header parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        switch (sh->slice_type) {
+        case EVC_SLICE_TYPE_B: {
+            s->pict_type =  AV_PICTURE_TYPE_B;
+            break;
+        }
+        case EVC_SLICE_TYPE_P: {
+            s->pict_type =  AV_PICTURE_TYPE_P;
+            break;
+        }
+        case EVC_SLICE_TYPE_I: {
+            s->pict_type =  AV_PICTURE_TYPE_I;
+            break;
+        }
+        default: {
+            s->pict_type =  AV_PICTURE_TYPE_NONE;
+        }
+        }
+
+        s->key_frame = (nalu_type == EVC_IDR_NUT) ? 1 : 0;
+
+        // 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
+        slice_pic_parameter_set_id = sh->slice_pic_parameter_set_id;
+        sps = &ev->sps[slice_pic_parameter_set_id];
+
+        if (sps->sps_pocs_flag) {
+
+            int PicOrderCntMsb = 0;
+            ev->poc.prevPicOrderCntVal = ev->poc.PicOrderCntVal;
+
+            if (nalu_type == EVC_IDR_NUT)
+                PicOrderCntMsb = 0;
+            else {
+                int MaxPicOrderCntLsb = 1 << (sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
+
+                int prevPicOrderCntLsb = ev->poc.PicOrderCntVal & (MaxPicOrderCntLsb - 1);
+                int prevPicOrderCntMsb = ev->poc.PicOrderCntVal - prevPicOrderCntLsb;
+
+
+                if ((sh->slice_pic_order_cnt_lsb < prevPicOrderCntLsb) &&
+                    ((prevPicOrderCntLsb - sh->slice_pic_order_cnt_lsb) >= (MaxPicOrderCntLsb / 2)))
+
+                    PicOrderCntMsb = prevPicOrderCntMsb + MaxPicOrderCntLsb;
+
+                else if ((sh->slice_pic_order_cnt_lsb > prevPicOrderCntLsb) &&
+                         ((sh->slice_pic_order_cnt_lsb - prevPicOrderCntLsb) > (MaxPicOrderCntLsb / 2)))
+
+                    PicOrderCntMsb = prevPicOrderCntMsb - MaxPicOrderCntLsb;
+
+                else
+                    PicOrderCntMsb = prevPicOrderCntMsb;
+            }
+            ev->poc.PicOrderCntVal = PicOrderCntMsb + sh->slice_pic_order_cnt_lsb;
+
+        } else {
+            if (nalu_type == EVC_IDR_NUT) {
+                ev->poc.PicOrderCntVal = 0;
+                ev->poc.DocOffset = -1;
+            } else {
+                int SubGopLength = (int)pow(2.0, sps->log2_sub_gop_length);
+                if (tid == 0) {
+                    ev->poc.PicOrderCntVal = ev->poc.prevPicOrderCntVal + SubGopLength;
+                    ev->poc.DocOffset = 0;
+                    ev->poc.prevPicOrderCntVal = ev->poc.PicOrderCntVal;
+                } else {
+                    int ExpectedTemporalId;
+                    int PocOffset;
+                    int prevDocOffset = ev->poc.DocOffset;
+
+                    ev->poc.DocOffset = (prevDocOffset + 1) % SubGopLength;
+                    if (ev->poc.DocOffset == 0) {
+                        ev->poc.prevPicOrderCntVal += SubGopLength;
+                        ExpectedTemporalId = 0;
+                    } else
+                        ExpectedTemporalId = 1 + (int)log2(ev->poc.DocOffset);
+                    while (tid != ExpectedTemporalId) {
+                        ev->poc.DocOffset = (ev->poc.DocOffset + 1) % SubGopLength;
+                        if (ev->poc.DocOffset == 0)
+                            ExpectedTemporalId = 0;
+                        else
+                            ExpectedTemporalId = 1 + (int)log2(ev->poc.DocOffset);
+                    }
+                    PocOffset = (int)(SubGopLength * ((2.0 * ev->poc.DocOffset + 1) / (int)pow(2.0, tid) - 2));
+                    ev->poc.PicOrderCntVal = ev->poc.prevPicOrderCntVal + PocOffset;
+                }
+            }
+        }
+
+        s->output_picture_number = ev->poc.PicOrderCntVal;
+        s->key_frame = (nalu_type == EVC_IDR_NUT) ? 1 : 0;
+
+        return 0;
+    }
+    data += (nalu_size - EVC_NALU_HEADER_SIZE);
+    data_size -= (nalu_size - EVC_NALU_HEADER_SIZE);
+
+    return 0;
+}
+
+// Reconstruct NAL Unit from incomplete data
+//
+// Assemble the NALU prefix storing NALU length if it has been split between 2 subsequent buffers (input chunks) incoming to the parser.
+// This is the case when the buffer size is not enough for the buffer to store the whole NAL unit prefix.
+// In this case, we have to get part of the prefix from the previous buffer and assemble it with the rest from the current buffer.
+// Then we'll be able to read NAL unit size.
+static int evc_assemble_nalu_prefix(AVCodecParserContext *s, const uint8_t *data, int data_size,
+                                    uint8_t *nalu_prefix, AVCodecContext *avctx)
+{
+    EVCParserContext *ctx = s->priv_data;
+    ParseContext     *pc = &ctx->pc;
+
+    // 1. pc->buffer contains previously read bytes of NALU prefix
+    // 2. buf contains the rest of NAL unit prefix bytes
+
+    for (int i = 0; i < EVC_NALU_LENGTH_PREFIX_SIZE; i++) {
+        if (i < pc->index)
+            nalu_prefix[i] = pc->buffer[i];
+        else
+            nalu_prefix[i] = data[i - pc->index];
+    }
+
+    return 0;
+}
+
+// Reconstruct NALU from incomplete data
+// Assemble NALU if it is split between multiple buffers
+//
+// This is the case when the buffer size is not enough to store the entire NAL unit.
+// In this scenario, we must retrieve parts of the NALU from the previous buffers stored in pc->buffer and assemble them with the remainder from the current buffer.
+static int evc_assemble_nalu(AVCodecParserContext *s, const uint8_t *data, int data_size,
+                             uint8_t *nalu, int nalu_size,
+                             AVCodecContext *avctx)
+{
+    EVCParserContext *ctx = s->priv_data;
+    ParseContext     *pc = &ctx->pc;
+
+    // 1. pc->buffer contains previously read bytes of the current NALU and previous NALUs that belong to the current Access Unit.
+    //
+    //    - previously read bytes are data that came with the previous incoming data chunks.
+    //
+    //    - pc->buffer contains bytes of the current NALU that have already been read while processing previous chunks of incoming data,
+    //      as well as already read bytes of previous NALUs belonging to the same Access Unit.
+    //
+    //    - ctx->bytes_read is the index of the the first element of the current NALU int the pc->buffer.
+    //    - The pc->index is the index of the element located right next to the last element of the current NALU in the pc->buffer.
+    //    - The elements of pc->buffer located before ctx->bytes_read index contain previously read NALUs of the current Access Unit.
+    //
+    // 2. buf contains the rest of the NAL unit bytestime_base
+    //
+    //    - ctx->to_read number of bytes to read from buf (the index of the element right next to the last element to read)
+
+    uint8_t *prev_data = pc->buffer + ctx->bytes_read;
+    int prev_data_size = pc->index - ctx->bytes_read;
+
+    memcpy(nalu, prev_data, prev_data_size);
+    memcpy(nalu + prev_data_size, data, data_size);
+
+    return 0;
+}
+
+static int end_of_access_unit_found(AVCodecParserContext *s, AVCodecContext *avctx)
+{
+    EVCParserContext *ctx = s->priv_data;
+
+    if (avctx->profile == 0) { // BASELINE profile
+        if (ctx->nalu_type == EVC_NOIDR_NUT || ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    } else { // MAIN profile
+        EVCParserContext *ev = s->priv_data;
+        if (ctx->nalu_type == EVC_NOIDR_NUT) {
+            if (ev->poc.PicOrderCntVal != ev->poc.prevPicOrderCntVal)
+                return 1;
+        } else if (ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    }
+    return 0;
+}
+
+// Find the end of the current frame in the bitstream.
+// The end of frame is the end of Access Unit.
+// Function returns the position of the first byte of the next frame, or END_NOT_FOUND
+static int evc_find_frame_end(AVCodecParserContext *s, const uint8_t *buf,
+                              int buf_size, AVCodecContext *avctx)
+{
+    EVCParserContext *ctx = s->priv_data;
+
+    const uint8_t *data = buf;
+    int data_size = buf_size;
+
+    while (data_size > 0) {
+
+        if (ctx->to_read == 0) {
+            // Nothing must be read and appended to the data from previous chunks.
+            // The previous chunk of data provided the complete NALU prefix or provided the complete NALU.
+
+            if (ctx->nalu_prefix_assembled)   // NALU prefix has been assembled from previous and current chunks of incoming data
+                ctx->nalu_prefix_assembled = 0;
+            else { // Buffer size is not enough for buffer to store NAL unit 4-bytes prefix (length)
+                if (data_size < EVC_NALU_LENGTH_PREFIX_SIZE) {
+                    ctx->to_read = EVC_NALU_LENGTH_PREFIX_SIZE - data_size;
+                    ctx->incomplete_nalu_prefix_read = 1;
+                    return END_NOT_FOUND;
+                }
+
+                ctx->nalu_size = read_nal_unit_length(data, data_size, avctx);
+                ctx->bytes_read += EVC_NALU_LENGTH_PREFIX_SIZE;
+
+                data += EVC_NALU_LENGTH_PREFIX_SIZE;
+                data_size -= EVC_NALU_LENGTH_PREFIX_SIZE;
+            }
+
+            if (data_size < ctx->nalu_size) {
+
+                ctx->to_read = ctx->nalu_size - data_size;
+                ctx->incomplete_nalu_read = 1;
+                return END_NOT_FOUND;
+            }
+
+            // the entire NALU can be read
+            if (parse_nal_unit(s, data, ctx->nalu_size, avctx) != 0) {
+                av_log(avctx, AV_LOG_ERROR, "Parsing of NAL unit failed\n");
+                return AVERROR_INVALIDDATA;
+            }
+
+            data += ctx->nalu_size;
+            data_size -= ctx->nalu_size;
+
+            ctx->bytes_read += ctx->nalu_size;
+
+            if (end_of_access_unit_found(s, avctx)) {
+
+                // parser should return buffer that contains complete AU
+                int read_bytes = ctx->bytes_read;
+                ctx->bytes_read = 0;
+                return read_bytes;
+            }
+
+            // go to the next iteration
+            continue;
+
+        } else {
+            // The previous chunk of input data did not contain the complete valid NALU prefix or did not contain the complete NALU.
+            //
+            // Missing data must be read from the current data chunk and merged with the data from the previous data chunk
+            // to assemble a complete  NALU or complete NALU prefix.
+            //
+            // The data from the previous data chunk are stored in pc->buf
+
+            if (ctx->to_read < data_size) {
+
+                if (ctx->incomplete_nalu_prefix_read == 1) {
+
+                    uint8_t nalu_prefix[EVC_NALU_LENGTH_PREFIX_SIZE];
+                    evc_assemble_nalu_prefix(s, data, data_size, nalu_prefix, avctx);
+
+                    ctx->nalu_size = read_nal_unit_length(nalu_prefix, EVC_NALU_LENGTH_PREFIX_SIZE, avctx);
+
+                    // update variable storing amout of read bytes for teh current AU
+                    ctx->bytes_read += ctx->to_read;
+
+                    // update data pointer and data size
+                    data += ctx->to_read;
+                    data_size -= ctx->to_read;
+
+                    // reset variable storing amount of bytes to read from the new data chunk
+                    ctx->to_read = 0;
+
+                    ctx->incomplete_nalu_prefix_read = 0;
+                    ctx->nalu_prefix_assembled = 1;
+
+                    continue;
+                }
+                if (ctx->incomplete_nalu_read == 1) {
+
+                    uint8_t *nalu = (uint8_t *)av_malloc(ctx->nalu_size);
+
+                    // assemble NAL unit using data from previous data chunks (pc->buffer) and the current one (data)
+                    evc_assemble_nalu(s, data, ctx->to_read, nalu, ctx->nalu_size, avctx);
+
+                    if (parse_nal_unit(s, nalu, ctx->nalu_size, avctx) != 0) {
+                        av_log(avctx, AV_LOG_ERROR, "Parsing of NAL unit failed\n");
+                        return AVERROR_INVALIDDATA;
+                    }
+                    av_free(nalu);
+
+                    // update variable storing amout of read bytes for teh current AU
+                    ctx->bytes_read += ctx->nalu_size;
+
+                    // update data pointer and data size
+                    data += ctx->to_read;
+                    data_size -= ctx->to_read;
+
+                    ctx->incomplete_nalu_read = 0;
+
+                    if (end_of_access_unit_found(s, avctx)) {
+
+                        // parser should return buffer that contains complete AU
+                        int read_bytes = ctx->to_read;
+
+                        ctx->to_read = 0;
+                        ctx->bytes_read = 0;
+
+                        return read_bytes;
+                    }
+
+                    // reset variable storing amount of bytes to read from the new data chunk
+                    ctx->to_read = 0;
+
+                    continue;
+                }
+            } else {
+                // needed more input data to assemble complete valid NAL Unit
+                ctx->to_read = ctx->to_read - data_size;
+                return END_NOT_FOUND;
+            }
+        }
+    }
+
+    return END_NOT_FOUND;
+}
+
+static int evc_parse(AVCodecParserContext *s, AVCodecContext *avctx,
+                     const uint8_t **poutbuf, int *poutbuf_size,
+                     const uint8_t *buf, int buf_size)
+{
+    int next;
+    EVCParserContext *ev = s->priv_data;
+    ParseContext *pc = &ev->pc;
+
+    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES)
+        next = buf_size;
+    else {
+        next = evc_find_frame_end(s, buf, buf_size, avctx);
+        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
+            *poutbuf      = NULL;
+            *poutbuf_size = 0;
+            return buf_size;
+        }
+    }
+
+    // poutbuf contains just one Access Unit
+    *poutbuf      = buf;
+    *poutbuf_size = buf_size;
+
+    return next;
+}
+
+static int evc_parser_init(AVCodecParserContext *s)
+{
+    EVCParserContext *ev = s->priv_data;
+    ev->incomplete_nalu_prefix_read = 0;
+
+    return 0;
+}
+
+const AVCodecParser ff_evc_parser = {
+    .codec_ids      = { AV_CODEC_ID_EVC },
+    .priv_data_size = sizeof(EVCParserContext),
+    .parser_init    = evc_parser_init,
+    .parser_parse   = evc_parse,
+    .parser_close   = ff_parse_close,
+};
diff --git a/libavcodec/parsers.c b/libavcodec/parsers.c
index d355808018..2c077ec3ae 100644
--- a/libavcodec/parsers.c
+++ b/libavcodec/parsers.c
@@ -41,6 +41,7 @@ extern const AVCodecParser ff_dvaudio_parser;
 extern const AVCodecParser ff_dvbsub_parser;
 extern const AVCodecParser ff_dvdsub_parser;
 extern const AVCodecParser ff_dvd_nav_parser;
+extern const AVCodecParser ff_evc_parser;
 extern const AVCodecParser ff_flac_parser;
 extern const AVCodecParser ff_ftr_parser;
 extern const AVCodecParser ff_g723_1_parser;
-- 
2.25.1



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