[FFmpeg-devel] [PATCH v23 04/10] avformat/evc_demuxer: Added demuxer to handle reading EVC video files

* [FFmpeg-devel] [PATCH v23 04/10] avformat/evc_demuxer: Added demuxer to handle reading EVC video files
       [not found] <CGME20230526103158eucas1p1e8b2adfc43aaf57c62e23e78571df817@eucas1p1.samsung.com>
@ 2023-05-26 10:31 ` Dawid Kozinski
  2023-05-29 13:07   ` James Almer
  0 siblings, 1 reply; 8+ messages in thread
From: Dawid Kozinski @ 2023-05-26 10:31 UTC (permalink / raw)
  To: d.frankiewic, ffmpeg-devel; +Cc: Dawid Kozinski

- Provided AVInputFormat struct describing EVC input format (ff_evc_demuxer)

Signed-off-by: Dawid Kozinski <d.kozinski@samsung.com>
---
 libavcodec/Makefile              |   1 +
 libavcodec/evc_frame_merge_bsf.c | 857 +++++++++++++++++++++++++++++++
 libavformat/Makefile             |   1 +
 libavformat/allformats.c         |   1 +
 libavformat/evcdec.c             | 334 ++++++++++++
 5 files changed, 1194 insertions(+)
 create mode 100644 libavcodec/evc_frame_merge_bsf.c
 create mode 100644 libavformat/evcdec.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index c598e8d6ca..a5a0c58750 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1251,6 +1251,7 @@ OBJS-$(CONFIG_VP9_METADATA_BSF)           += vp9_metadata_bsf.o
 OBJS-$(CONFIG_VP9_RAW_REORDER_BSF)        += vp9_raw_reorder_bsf.o
 OBJS-$(CONFIG_VP9_SUPERFRAME_BSF)         += vp9_superframe_bsf.o
 OBJS-$(CONFIG_VP9_SUPERFRAME_SPLIT_BSF)   += vp9_superframe_split_bsf.o
+OBJS-$(CONFIG_EVC_FRAME_MERGE_BSF)        += evc_frame_merge_bsf.o
 
 # thread libraries
 OBJS-$(HAVE_LIBC_MSVCRT)               += file_open.o
diff --git a/libavcodec/evc_frame_merge_bsf.c b/libavcodec/evc_frame_merge_bsf.c
new file mode 100644
index 0000000000..7cfcfaa335
--- /dev/null
+++ b/libavcodec/evc_frame_merge_bsf.c
@@ -0,0 +1,857 @@
+/*
+ * Copyright (c) 2019 James Almer <jamrial@gmail.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 "get_bits.h"
+#include "golomb.h"
+#include "bsf.h"
+#include "bsf_internal.h"
+#include "avcodec.h"
+
+#include "evc.h"
+
+#define INIT_AU_BUF_CAPACITY 1024
+
+// 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) OK
+
+    // @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;
+
+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;
+
+// Access unit data
+typedef struct AccessUnitBuffer {
+    uint8_t *data;      // the data buffer
+    size_t data_size;   // size of data in bytes
+    size_t capacity;    // buffer capacity
+} AccessUnitBuffer;
+
+typedef struct EVCMergeContext {
+    AVPacket *in;
+
+    EVCParserSPS *sps[EVC_MAX_SPS_COUNT];
+    EVCParserPPS *pps[EVC_MAX_PPS_COUNT];
+    EVCParserSliceHeader *slice_header[EVC_MAX_PPS_COUNT];
+
+    EVCParserPoc poc;
+
+    // the Baseline profile is indicated by profile eqal to 0
+    // the Main profile is indicated by profile eqal to 1
+    int profile;
+    int nalu_type;                  // the current NALU type
+    int nalu_size;                  // the current NALU size
+
+    int key_frame;
+
+    AccessUnitBuffer au_buffer;
+
+} EVCMergeContext;
+
+// nuh_temporal_id specifies a temporal identifier for the NAL unit
+static int get_temporal_id(const uint8_t *bits, int bits_size)
+{
+    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;
+}
+
+static int get_nalu_type(const uint8_t *bits, int bits_size)
+{
+    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)   // Cannot get bitstream information. Malformed bitstream.
+            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)
+{
+    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)   // Invalid bitstream size
+            return 0;
+    }
+
+    return nalu_len;
+}
+
+static int end_of_access_unit_found(AVBSFContext *s)
+{
+    EVCMergeContext *ctx = s->priv_data;
+
+    if (ctx->profile == 0) { // BASELINE profile
+        if (ctx->nalu_type == EVC_NOIDR_NUT || ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    } else { // MAIN profile
+        if (ctx->nalu_type == EVC_NOIDR_NUT) {
+            if (ctx->poc.PicOrderCntVal != ctx->poc.prevPicOrderCntVal)
+                return 1;
+        } else if (ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    }
+    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, EVCMergeContext *ctx)
+{
+    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;
+
+    if(!ctx->sps[sps_seq_parameter_set_id]) {
+        if((ctx->sps[sps_seq_parameter_set_id] = av_malloc(sizeof(EVCParserSPS))) == NULL)
+            return NULL;
+    }
+
+    sps = ctx->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);
+
+    skip_bits_long(&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);
+
+    get_ue_golomb(&gb); /* skip pic_width_in_luma_samples */
+    get_ue_golomb(&gb); /* skip pic_height_in_luma_samples */
+
+    get_ue_golomb(&gb); /* skip bit_depth_luma_minus8 = */
+    get_ue_golomb(&gb); /* skip bit_depth_chroma_minus8 = */
+
+    sps->sps_btt_flag = get_bits(&gb, 1);
+    if (sps->sps_btt_flag) {
+        get_ue_golomb(&gb); /* skip log2_ctu_size_minus5 */
+        get_ue_golomb(&gb); /* skip log2_min_cb_size_minus2 */
+        get_ue_golomb(&gb); /* skip log2_diff_ctu_max_14_cb_size */
+        get_ue_golomb(&gb); /* skip log2_diff_ctu_max_tt_cb_size */
+        get_ue_golomb(&gb); /* skip log2_diff_min_cb_min_tt_cb_size_minus2 */
+    }
+
+    sps->sps_suco_flag = get_bits(&gb, 1);
+    if (sps->sps_suco_flag) {
+        get_ue_golomb(&gb); /* skip log2_diff_ctu_size_max_suco_cb_size = */
+        get_ue_golomb(&gb); /* skip log2_diff_max_suco_min_suco_cb_size = */
+    }
+
+    sps->sps_admvp_flag = get_bits(&gb, 1);
+    if (sps->sps_admvp_flag) {
+        skip_bits_long(&gb, 1); /* skip sps_affine_flag */
+        skip_bits_long(&gb, 1); /* skip sps_amvr_flag */
+        skip_bits_long(&gb, 1); /* skip sps_dmvr_flag */
+
+        sps->sps_mmvd_flag = get_bits(&gb, 1);
+
+        skip_bits_long(&gb, 1); /* skip sps_hmvp_flag */
+    }
+
+    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)
+            get_ue_golomb(&gb); /* skip log2_max_ibc_cand_size_minus2 */
+    }
+
+    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)
+        skip_bits_long(&gb, 1); /* skip sps_ats_flag */
+
+    skip_bits_long(&gb, 1); /* skip sps_addb_flag */
+
+    sps->sps_alf_flag = get_bits(&gb, 1);
+
+    skip_bits_long(&gb, 1); /* skip sps->sps_htdf_flag */
+
+    sps->sps_rpl_flag = get_bits(&gb, 1);
+    sps->sps_pocs_flag = get_bits(&gb, 1);
+
+    skip_bits_long(&gb, 1); /* skip sps_dquant_flag */
+    skip_bits_long(&gb, 1); /* skip sps_dra_flag */
+
+    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);
+
+    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, EVCMergeContext *ctx)
+{
+    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;
+
+    if(!ctx->pps[pps_pic_parameter_set_id]) {
+        if((ctx->pps[pps_pic_parameter_set_id] = av_malloc(sizeof(EVCParserSPS))) == NULL)
+            return NULL;
+    }
+
+    pps = ctx->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;
+
+    get_ue_golomb(&gb); /* skip num_ref_idx_default_active_minus1[0] */
+    get_ue_golomb(&gb); /* skip num_ref_idx_default_active_minus1[1] */
+    get_ue_golomb(&gb); /* skip additional_lt_poc_lsb_len */
+    skip_bits_long(&gb, 1); /* skip rpl1_idx_present_flag */
+    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++)
+                get_ue_golomb(&gb); /* skip tile_column_width_minus1[i] */
+
+            for (int i = 0; i < pps->num_tile_rows_minus1; i++)
+                get_ue_golomb(&gb); /* skip tile_row_height_minus1[i] */
+        }
+        skip_bits_long(&gb, 1);     /* skip loop_filter_across_tiles_enabled_flag */
+        get_ue_golomb(&gb);         /* skip tile_offset_len_minus1 */
+    }
+
+    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++)
+                skip_bits_long(&gb, pps->tile_id_len_minus1 + 1); /* skip tile_id_val[i][j] */;
+        }
+    }
+
+    pps->pic_dra_enabled_flag = 0;
+    pps->pic_dra_enabled_flag = get_bits(&gb, 1);
+
+    if (pps->pic_dra_enabled_flag)
+        skip_bits_long(&gb, 5); /* skip pic_dra_aps_id */
+
+    pps->arbitrary_slice_present_flag = get_bits(&gb, 1);
+
+    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, EVCMergeContext *ctx)
+{
+    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;
+
+    if(!ctx->slice_header[slice_pic_parameter_set_id]) {
+        if((ctx->slice_header[slice_pic_parameter_set_id] = av_malloc(sizeof(EVCParserSliceHeader))) == NULL)
+            return NULL;
+    }
+
+    sh = ctx->slice_header[slice_pic_parameter_set_id];
+
+    pps = ctx->pps[slice_pic_parameter_set_id];
+    if(!pps)
+        return NULL;
+
+    sps = ctx->sps[slice_pic_parameter_set_id];
+    if(!sps)
+        return NULL;
+
+    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);
+        skip_bits_long(&gb, pps->tile_id_len_minus1 + 1); /* skip first_tile_id */
+    } 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)
+            skip_bits_long(&gb, pps->tile_id_len_minus1 + 1); /* skip last_tile_id */
+        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)
+                get_ue_golomb(&gb); /* skip delta_tile_id_minus1[i] */
+        }
+    }
+
+    sh->slice_type = get_ue_golomb(&gb);
+
+    if (ctx->nalu_type == EVC_IDR_NUT)
+        skip_bits_long(&gb, 1);     /* skip no_output_of_prior_pics_flag */
+
+    if (sps->sps_mmvd_flag && ((sh->slice_type == EVC_SLICE_TYPE_B) || (sh->slice_type == EVC_SLICE_TYPE_P)))
+        skip_bits_long(&gb, 1);     /* skip mmvd_group_enable_flag */
+    // 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) {
+                skip_bits_long(&gb, 5); /* skip slice_alf_chroma_aps_id */
+                skip_bits_long(&gb, 1); /* skip slice_alf_chroma_map_flag */
+            }
+
+            if (sliceChroma2AlfEnabledFlag) {
+                skip_bits_long(&gb, 5); /* skip slice_alf_chroma2_aps_id */
+                skip_bits_long(&gb, 1); /* skip slice_alf_chroma2_map_flag */
+            }
+        }
+    }
+
+    if (ctx->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(const uint8_t *buf, size_t buf_size, AVBSFContext *s)
+{
+    int nalu_type, nalu_size;
+    int tid;
+    const uint8_t *data = buf;
+    int data_size = buf_size;
+    EVCMergeContext *ctx = s->priv_data;
+
+    nalu_size = buf_size;
+    if (nalu_size <= 0) {
+        av_log(s, 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);
+    if (nalu_type < EVC_NOIDR_NUT || nalu_type > EVC_UNSPEC_NUT62) {
+        av_log(s, AV_LOG_ERROR, "Invalid NAL unit type: (%d)\n", nalu_type);
+        return AVERROR_INVALIDDATA;
+    }
+    ctx->nalu_type = nalu_type;
+
+    tid = get_temporal_id(data, data_size);
+    if (tid < 0) {
+        av_log(s, AV_LOG_ERROR, "Invalid temporial id: (%d)\n", tid);
+        return AVERROR_INVALIDDATA;
+    }
+
+    data += EVC_NALU_HEADER_SIZE;
+    data_size -= EVC_NALU_HEADER_SIZE;
+
+    switch(nalu_type) {
+    case EVC_SPS_NUT: {
+        EVCParserSPS *sps;
+
+        sps = parse_sps(data, nalu_size, ctx);
+        if (!sps) {
+            av_log(s, AV_LOG_ERROR, "SPS parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        if (sps->profile_idc == 1) ctx->profile = FF_PROFILE_EVC_MAIN;
+        else ctx->profile = FF_PROFILE_EVC_BASELINE;
+
+        break;
+    }
+    case EVC_PPS_NUT: {
+        EVCParserPPS *pps;
+
+        pps = parse_pps(data, nalu_size, ctx);
+        if (!pps) {
+            av_log(s, AV_LOG_ERROR, "PPS parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+        break;
+    }
+    case EVC_SEI_NUT:   // Supplemental Enhancement Information
+    case EVC_APS_NUT:   // Adaptation parameter set
+    case EVC_FD_NUT:    // Filler data
+        break;
+    case EVC_IDR_NUT:   // Coded slice of a IDR or non-IDR picture
+    case EVC_NOIDR_NUT: {
+        EVCParserSliceHeader *sh;
+        EVCParserSPS *sps;
+        int slice_pic_parameter_set_id;
+
+        sh = parse_slice_header(data, nalu_size, ctx);
+        if (!sh) {
+            av_log(s, AV_LOG_ERROR, "Slice header parsing error\n");
+            return AVERROR_INVALIDDATA;
+        }
+
+        ctx->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 = ctx->sps[slice_pic_parameter_set_id];
+
+        if (sps && sps->sps_pocs_flag) {
+
+            int PicOrderCntMsb = 0;
+            ctx->poc.prevPicOrderCntVal = ctx->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 = ctx->poc.PicOrderCntVal & (MaxPicOrderCntLsb - 1);
+                int prevPicOrderCntMsb = ctx->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;
+            }
+            ctx->poc.PicOrderCntVal = PicOrderCntMsb + sh->slice_pic_order_cnt_lsb;
+
+        } else {
+            if (nalu_type == EVC_IDR_NUT) {
+                ctx->poc.PicOrderCntVal = 0;
+                ctx->poc.DocOffset = -1;
+            } else {
+                int SubGopLength = (int)pow(2.0, sps->log2_sub_gop_length);
+                if (tid == 0) {
+                    ctx->poc.PicOrderCntVal = ctx->poc.prevPicOrderCntVal + SubGopLength;
+                    ctx->poc.DocOffset = 0;
+                    ctx->poc.prevPicOrderCntVal = ctx->poc.PicOrderCntVal;
+                } else {
+                    int ExpectedTemporalId;
+                    int PocOffset;
+                    int prevDocOffset = ctx->poc.DocOffset;
+
+                    ctx->poc.DocOffset = (prevDocOffset + 1) % SubGopLength;
+                    if (ctx->poc.DocOffset == 0) {
+                        ctx->poc.prevPicOrderCntVal += SubGopLength;
+                        ExpectedTemporalId = 0;
+                    } else
+                        ExpectedTemporalId = 1 + (int)log2(ctx->poc.DocOffset);
+                    while (tid != ExpectedTemporalId) {
+                        ctx->poc.DocOffset = (ctx->poc.DocOffset + 1) % SubGopLength;
+                        if (ctx->poc.DocOffset == 0)
+                            ExpectedTemporalId = 0;
+                        else
+                            ExpectedTemporalId = 1 + (int)log2(ctx->poc.DocOffset);
+                    }
+                    PocOffset = (int)(SubGopLength * ((2.0 * ctx->poc.DocOffset + 1) / (int)pow(2.0, tid) - 2));
+                    ctx->poc.PicOrderCntVal = ctx->poc.prevPicOrderCntVal + PocOffset;
+                }
+            }
+        }
+
+        break;
+    }
+    }
+
+    return 0;
+}
+
+static void evc_frame_merge_flush(AVBSFContext *bsf)
+{
+    EVCMergeContext *ctx = bsf->priv_data;
+
+    av_packet_unref(ctx->in);
+}
+
+static int evc_frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
+{
+    EVCMergeContext *ctx = bsf->priv_data;
+    AVPacket *in = ctx->in;
+
+    int free_space = 0;
+    size_t  nalu_size = 0;
+    uint8_t *nalu = NULL;
+    int au_end_found = 0;
+    int err;
+
+    err = ff_bsf_get_packet_ref(bsf, in);
+    if (err < 0)
+        return err;
+
+    nalu_size = read_nal_unit_length(in->data, EVC_NALU_LENGTH_PREFIX_SIZE);
+    if(nalu_size <= 0) {
+        av_packet_unref(in);
+        return AVERROR_INVALIDDATA;
+    }
+
+    nalu = in->data + EVC_NALU_LENGTH_PREFIX_SIZE;
+    nalu_size = in->size - EVC_NALU_LENGTH_PREFIX_SIZE;
+
+    // NAL unit parsing needed to determine if end of AU was found
+    err = parse_nal_unit(nalu, nalu_size, bsf);
+    if (err < 0) {
+        av_log(bsf, AV_LOG_ERROR, "NAL Unit parsing error\n");
+        av_packet_unref(in);
+
+        return err;
+    }
+
+    au_end_found = end_of_access_unit_found(bsf);
+
+    free_space = ctx->au_buffer.capacity - ctx->au_buffer.data_size;
+    while( free_space < in->size ) {
+        ctx->au_buffer.capacity *= 2;
+        free_space = ctx->au_buffer.capacity - ctx->au_buffer.data_size;
+
+        if(free_space >= in->size) {
+            ctx->au_buffer.data = av_realloc(ctx->au_buffer.data, ctx->au_buffer.capacity);
+        }
+    }
+
+    memcpy(ctx->au_buffer.data + ctx->au_buffer.data_size, in->data, in->size);
+
+    ctx->au_buffer.data_size += in->size;
+
+    av_packet_unref(in);
+
+    if(au_end_found) {
+        uint8_t *data = av_memdup(ctx->au_buffer.data, ctx->au_buffer.data_size);
+        err = av_packet_from_data(out, data, ctx->au_buffer.data_size);
+
+        ctx->au_buffer.data_size = 0;
+    } else
+        err = AVERROR(EAGAIN);
+
+    if (err < 0 && err != AVERROR(EAGAIN))
+        evc_frame_merge_flush(bsf);
+
+    return err;
+}
+
+static int evc_frame_merge_init(AVBSFContext *bsf)
+{
+    EVCMergeContext *ctx = bsf->priv_data;
+
+    ctx->in  = av_packet_alloc();
+    if (!ctx->in)
+        return AVERROR(ENOMEM);
+
+    ctx->au_buffer.capacity = INIT_AU_BUF_CAPACITY;
+    ctx->au_buffer.data = av_malloc(INIT_AU_BUF_CAPACITY);
+    ctx->au_buffer.data_size = 0;
+
+    return 0;
+}
+
+static void evc_frame_merge_close(AVBSFContext *bsf)
+{
+    EVCMergeContext *ctx = bsf->priv_data;
+
+    av_packet_free(&ctx->in);
+
+    ctx->au_buffer.capacity = 0;
+    av_freep(&ctx->au_buffer.data);
+    ctx->au_buffer.data_size = 0;
+}
+
+static const enum AVCodecID evc_frame_merge_codec_ids[] = {
+    AV_CODEC_ID_EVC, AV_CODEC_ID_NONE,
+};
+
+const FFBitStreamFilter ff_evc_frame_merge_bsf = {
+    .p.name         = "evc_frame_merge",
+    .p.codec_ids    = evc_frame_merge_codec_ids,
+    .priv_data_size = sizeof(EVCMergeContext),
+    .init           = evc_frame_merge_init,
+    .flush          = evc_frame_merge_flush,
+    .close          = evc_frame_merge_close,
+    .filter         = evc_frame_merge_filter,
+};
\ No newline at end of file
diff --git a/libavformat/Makefile b/libavformat/Makefile
index a734ad64ca..bd717dc6b5 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -251,6 +251,7 @@ OBJS-$(CONFIG_HCOM_DEMUXER)              += hcom.o pcm.o
 OBJS-$(CONFIG_HDS_MUXER)                 += hdsenc.o
 OBJS-$(CONFIG_HEVC_DEMUXER)              += hevcdec.o rawdec.o
 OBJS-$(CONFIG_HEVC_MUXER)                += rawenc.o
+OBJS-$(CONFIG_EVC_DEMUXER)               += evcdec.o rawdec.o
 OBJS-$(CONFIG_EVC_MUXER)                 += rawenc.o
 OBJS-$(CONFIG_HLS_DEMUXER)               += hls.o hls_sample_encryption.o
 OBJS-$(CONFIG_HLS_MUXER)                 += hlsenc.o hlsplaylist.o avc.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 2ad142d8f7..eb14c79bfa 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -154,6 +154,7 @@ extern const AVInputFormat  ff_ea_cdata_demuxer;
 extern const AVInputFormat  ff_eac3_demuxer;
 extern const FFOutputFormat ff_eac3_muxer;
 extern const AVInputFormat  ff_epaf_demuxer;
+extern const AVInputFormat  ff_evc_demuxer;
 extern const FFOutputFormat ff_evc_muxer;
 extern const FFOutputFormat ff_f4v_muxer;
 extern const AVInputFormat  ff_ffmetadata_demuxer;
diff --git a/libavformat/evcdec.c b/libavformat/evcdec.c
new file mode 100644
index 0000000000..b619576128
--- /dev/null
+++ b/libavformat/evcdec.c
@@ -0,0 +1,334 @@
+/*
+ * RAW EVC video demuxer
+ *
+ * Copyright (c) 2021 Dawid Kozinski <d.kozinski@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 "libavcodec/get_bits.h"
+#include "libavcodec/golomb.h"
+#include "libavcodec/internal.h"
+#include "libavcodec/evc.h"
+#include "libavcodec/bsf.h"
+
+#include "libavutil/opt.h"
+
+#include "rawdec.h"
+#include "avformat.h"
+#include "internal.h"
+
+
+#define RAW_PACKET_SIZE 1024
+
+typedef struct EVCParserContext {
+    int got_sps;
+    int got_pps;
+    int got_idr;
+    int got_nonidr;
+
+} EVCParserContext;
+
+typedef struct EVCDemuxContext {
+    const AVClass *class;
+    AVRational framerate;
+
+    AVBSFContext *bsf;
+
+} EVCDemuxContext;
+
+#define DEC AV_OPT_FLAG_DECODING_PARAM
+#define OFFSET(x) offsetof(EVCDemuxContext, x)
+static const AVOption evc_options[] = {
+    { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC},
+    { NULL },
+};
+#undef OFFSET
+
+static const AVClass evc_demuxer_class = {
+    .class_name = "EVC Annex B demuxer",
+    .item_name  = av_default_item_name,
+    .option     = evc_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static int get_nalu_type(const uint8_t *bits, int bits_size)
+{
+    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)   // Cannot get bitstream information. Malformed bitstream.
+            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)
+{
+    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)   // Invalid bitstream size
+            return 0;
+    }
+
+    return nalu_len;
+}
+
+static int parse_nal_units(const AVProbeData *p, EVCParserContext *ev)
+{
+    int nalu_type;
+    size_t nalu_size;
+    unsigned char *bits = (unsigned char *)p->buf;
+    int bytes_to_read = p->buf_size;
+
+    while (bytes_to_read > EVC_NALU_LENGTH_PREFIX_SIZE) {
+
+        nalu_size = read_nal_unit_length(bits, EVC_NALU_LENGTH_PREFIX_SIZE);
+        if (nalu_size == 0) break;
+
+        bits += EVC_NALU_LENGTH_PREFIX_SIZE;
+        bytes_to_read -= EVC_NALU_LENGTH_PREFIX_SIZE;
+
+        if(bytes_to_read < nalu_size) break;
+
+        nalu_type = get_nalu_type(bits, bytes_to_read);
+
+        if (nalu_type == EVC_SPS_NUT)
+            ev->got_sps++;
+        else if (nalu_type == EVC_PPS_NUT)
+            ev->got_pps++;
+        else if (nalu_type == EVC_IDR_NUT )
+            ev->got_idr++;
+        else if (nalu_type == EVC_NOIDR_NUT)
+            ev->got_nonidr++;
+
+        bits += nalu_size;
+        bytes_to_read -= nalu_size;
+    }
+
+    return 0;
+}
+
+static int annexb_probe(const AVProbeData *p)
+{
+    EVCParserContext ev = {0};
+    int ret = parse_nal_units(p, &ev);
+
+    if (ret == 0 && ev.got_sps && ev.got_pps && (ev.got_idr || ev.got_nonidr > 3))
+        return AVPROBE_SCORE_EXTENSION + 1;  // 1 more than .mpg
+
+    return 0;
+}
+
+static int annexb_read_header(AVFormatContext *s)
+{
+    AVStream *st;
+    FFStream *sti;
+    EVCDemuxContext *c = s->priv_data;
+    int ret = 0;
+
+    st = avformat_new_stream(s, NULL);
+    if (!st) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    sti = ffstream(st);
+
+    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+    st->codecpar->codec_id = AV_CODEC_ID_EVC;
+    sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
+
+    st->avg_frame_rate = c->framerate;
+    sti->avctx->framerate = c->framerate;
+
+    // taken from rawvideo demuxers
+    avpriv_set_pts_info(st, 64, 1, 1200000);
+
+fail:
+    return ret;
+}
+
+static int evc_read_header(AVFormatContext *s)
+{
+    AVStream *st;
+    FFStream *sti;
+    const AVBitStreamFilter *filter = av_bsf_get_by_name("evc_frame_merge");
+    EVCDemuxContext *c = s->priv_data;
+    int ret = 0;
+
+    st = avformat_new_stream(s, NULL);
+    if (!st) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    sti = ffstream(st);
+
+    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
+    st->codecpar->codec_id = AV_CODEC_ID_EVC;
+
+    // This causes sending to the parser full frames, not chunks of data
+    // The flag PARSER_FLAG_COMPLETE_FRAMES will be set in demux.c (demux.c: 1316)
+    sti->need_parsing = AVSTREAM_PARSE_HEADERS;
+
+    st->avg_frame_rate = c->framerate;
+    sti->avctx->framerate = c->framerate;
+
+    // taken from rawvideo demuxers
+    avpriv_set_pts_info(st, 64, 1, 1200000);
+
+    ret = av_bsf_alloc(filter, &c->bsf);
+    if (ret < 0)
+        return ret;
+
+    ret = avcodec_parameters_copy(c->bsf->par_in, st->codecpar);
+    if (ret < 0)
+        return ret;
+
+    ret = av_bsf_init(c->bsf);
+    if (ret < 0)
+        return ret;
+
+fail:
+    return ret;
+}
+
+static int annexb_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int ret, pkt_size;
+    int eof;
+
+    pkt_size = RAW_PACKET_SIZE;
+
+    eof = avio_feof (s->pb);
+    if(eof) {
+        av_packet_unref(pkt);
+        return AVERROR_EOF;
+    }
+
+    if ((ret = av_new_packet(pkt, pkt_size)) < 0)
+        return ret;
+
+    pkt->pos = avio_tell(s->pb);
+    pkt->stream_index = 0;
+    ret = avio_read_partial(s->pb, pkt->data, pkt_size);
+    if (ret < 0) {
+        av_packet_unref(pkt);
+        return ret;
+    }
+    av_shrink_packet(pkt, ret);
+
+    av_log(s, AV_LOG_ERROR, "annexb_read_packet: %d\n", pkt_size);
+
+    return ret;
+}
+
+static int evc_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int ret;
+    int32_t nalu_size;
+    int au_end_found;
+
+    EVCDemuxContext *const c = s->priv_data;
+
+    int eof = avio_feof (s->pb);
+    if(eof) {
+        av_packet_unref(pkt);
+        return AVERROR_EOF;
+    }
+
+    au_end_found = 0;
+
+    while(!au_end_found) {
+
+        uint8_t buf[EVC_NALU_LENGTH_PREFIX_SIZE];
+        ret = avio_read(s->pb, (unsigned char *)&buf, EVC_NALU_LENGTH_PREFIX_SIZE);
+        if (ret < 0) {
+            av_packet_unref(pkt);
+            return ret;
+        }
+
+        nalu_size = read_nal_unit_length((const uint8_t *)&buf, EVC_NALU_LENGTH_PREFIX_SIZE);
+        if(nalu_size <= 0) {
+            av_packet_unref(pkt);
+            return -1;
+        }
+
+        avio_seek(s->pb, -EVC_NALU_LENGTH_PREFIX_SIZE, SEEK_CUR);
+
+        ret = av_get_packet(s->pb, pkt, nalu_size + EVC_NALU_LENGTH_PREFIX_SIZE);
+        if (ret < 0)
+            return ret;
+        if (ret != (nalu_size + EVC_NALU_LENGTH_PREFIX_SIZE))
+            return AVERROR(EIO);
+
+        ret = av_bsf_send_packet(c->bsf, pkt);
+        if (ret < 0) {
+            av_log(s, AV_LOG_ERROR, "Failed to send packet to "
+                   "evc_frame_merge filter\n");
+            return ret;
+        }
+
+        ret = av_bsf_receive_packet(c->bsf, pkt);
+        if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
+            av_log(s, AV_LOG_ERROR, "evc_frame_merge filter failed to "
+                   "send output packet\n");
+
+        au_end_found = 1;
+        if (ret == AVERROR(EAGAIN))
+            au_end_found = 0;
+    }
+
+    return ret;
+}
+
+static int evc_read_close(AVFormatContext *s)
+{
+    EVCDemuxContext *const c = s->priv_data;
+
+    av_bsf_free(&c->bsf);
+    return 0;
+}
+
+const AVInputFormat ff_evc_demuxer = {
+    .name           = "evc",
+    .long_name      = NULL_IF_CONFIG_SMALL("EVC Annex B"),
+    .read_probe     = annexb_probe,
+    .read_header    = evc_read_header, // annexb_read_header
+    .read_packet    = evc_read_packet, // annexb_read_packet
+    .read_close     = evc_read_close,
+    .extensions     = "evc",
+    .flags          = AVFMT_GENERIC_INDEX,
+    .flags_internal = FF_FMT_INIT_CLEANUP,
+    .raw_codec_id   = AV_CODEC_ID_EVC,
+    .priv_data_size = sizeof(EVCDemuxContext),
+    .priv_class     = &evc_demuxer_class,
+};
-- 
2.25.1

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