avformat/evc_demuxer: Added demuxer to handle reading EVC video files

- Provided AVInputFormat struct describing EVC input format (ff_evc_demuxer)

Signed-off-by: Dawid Kozinski <d.kozinski@samsung.com>

1 files changed, 276 insertions, 0 deletions

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,
+};