[FFmpeg-devel,v25,3/9] avformat/evc_demuxer: Added demuxer to handle reading EVC video files

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index a28919992a..0ce8fe5b9c 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1258,6 +1258,7 @@  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/bitstream_filters.c b/libavcodec/bitstream_filters.c
index e8216819ca..7512fccc78 100644
--- a/libavcodec/bitstream_filters.c
+++ b/libavcodec/bitstream_filters.c
@@ -65,16 +65,17 @@  extern const FFBitStreamFilter ff_vp9_metadata_bsf;
 extern const FFBitStreamFilter ff_vp9_raw_reorder_bsf;
 extern const FFBitStreamFilter ff_vp9_superframe_bsf;
 extern const FFBitStreamFilter ff_vp9_superframe_split_bsf;
+extern const FFBitStreamFilter ff_evc_frame_merge_bsf;
 
 #include "libavcodec/bsf_list.c"
 
 const AVBitStreamFilter *av_bsf_iterate(void **opaque)
 {
-    uintptr_t i = (uintptr_t)*opaque;
+    uintptr_t i = (uintptr_t) * opaque;
     const FFBitStreamFilter *f = bitstream_filters[i];
 
     if (f) {
-        *opaque = (void*)(i + 1);
+        *opaque = (void *)(i + 1);
         return &f->p;
     }
     return NULL;
diff --git a/libavcodec/evc_frame_merge_bsf.c b/libavcodec/evc_frame_merge_bsf.c
new file mode 100644
index 0000000000..7f52c06292
--- /dev/null
+++ b/libavcodec/evc_frame_merge_bsf.c
@@ -0,0 +1,170 @@ 
+/*
+ * 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"
+#include "evc_parse.h"
+
+#define INIT_AU_BUF_CAPACITY 1024
+
+// 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 EVCFMergeContext {
+    AVPacket *in;
+    EVCParserContext parser_ctx;
+    AccessUnitBuffer au_buffer;
+} EVCFMergeContext;
+
+static int end_of_access_unit_found(EVCParserContext *parser_ctx)
+{
+    if (parser_ctx->profile == 0) { // BASELINE profile
+        if (parser_ctx->nalu_type == EVC_NOIDR_NUT || parser_ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    } else { // MAIN profile
+        if (parser_ctx->nalu_type == EVC_NOIDR_NUT) {
+            if (parser_ctx->poc.PicOrderCntVal != parser_ctx->poc.prevPicOrderCntVal)
+                return 1;
+        } else if (parser_ctx->nalu_type == EVC_IDR_NUT)
+            return 1;
+    }
+    return 0;
+}
+
+static void evc_frame_merge_flush(AVBSFContext *bsf)
+{
+    EVCFMergeContext *ctx = bsf->priv_data;
+
+    av_packet_unref(ctx->in);
+}
+
+static int evc_frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
+{
+    EVCFMergeContext *ctx = bsf->priv_data;
+    EVCParserContext *parser_ctx = &ctx->parser_ctx;
+
+    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 = ff_evc_read_nal_unit_length(in->data, EVC_NALU_LENGTH_PREFIX_SIZE, bsf);
+    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 = ff_evc_parse_nal_unit(parser_ctx, 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(parser_ctx);
+
+    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)
+{
+    EVCFMergeContext *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)
+{
+    EVCFMergeContext *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(EVCFMergeContext),
+    .init           = evc_frame_merge_init,
+    .flush          = evc_frame_merge_flush,
+    .close          = evc_frame_merge_close,
+    .filter         = evc_frame_merge_filter,
+};
diff --git a/libavformat/Makefile b/libavformat/Makefile
index f31135d806..6e4231fda2 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 d3871de268..ae604236ae 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..89eda0f53e
--- /dev/null
+++ b/libavformat/evcdec.c
@@ -0,0 +1,276 @@ 
+/*
+ * 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 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;
+    st->codecpar->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 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,
+};