The dirac raw bitstream contains enough framing information to make a
full demuxer out of it.
---
 libavformat/diracdec.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 143 insertions(+), 3 deletions(-)

diff --git a/libavformat/diracdec.c b/libavformat/diracdec.c
index f275212..4386f5d 100644
--- a/libavformat/diracdec.c
+++ b/libavformat/diracdec.c
@@ -1,6 +1,6 @@
 /*
  * RAW Dirac demuxer
- * Copyright (c) 2007 Marco Gerards <[email protected]>
+ * Copyright (c) 2016 Luca Barbato
  *
  * This file is part of Libav.
  *
@@ -19,9 +19,16 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavcodec/dirac.h"
 #include "libavutil/intreadwrite.h"
+
 #include "avformat.h"
-#include "rawdec.h"
+#include "internal.h"
+
+#define VC2_SEQUENCE_HEADER  0x00
+#define VC2_END_OF_SEQUENCE  0x10
+#define VC2_HQ_PICTURE       0xE8
+#define VC2_HEADER_SIZE (4 + 1 + 4 + 4)
 
 static int dirac_probe(AVProbeData *p)
 {
@@ -31,4 +38,137 @@ static int dirac_probe(AVProbeData *p)
         return 0;
 }
 
-FF_DEF_RAWVIDEO_DEMUXER(dirac, "raw Dirac", dirac_probe, NULL, 
AV_CODEC_ID_DIRAC)
+static int parse_header(AVFormatContext *s,
+                        uint32_t *payload_size)
+{
+    uint32_t start_code = avio_rl32(s->pb);
+    uint32_t prev_off, next_off;
+    int parse_code;
+
+    if (s->pb->eof_reached)
+        return AVERROR_EOF;
+
+    if (start_code != MKTAG('B', 'B', 'C', 'D')) {
+        av_log(NULL, AV_LOG_ERROR, "Bogus start_code %d\n",
+               start_code);
+        return AVERROR_INVALIDDATA;
+    }
+
+    parse_code = avio_r8(s->pb);
+    next_off   = avio_rb32(s->pb);
+    prev_off   = avio_rb32(s->pb);
+
+    *payload_size = next_off - VC2_HEADER_SIZE;
+
+    av_log(s, AV_LOG_VERBOSE,
+           "packet %s next %u prev %u \n",
+           parse_code == VC2_SEQUENCE_HEADER ? "Sequence Header" :
+           parse_code == VC2_HQ_PICTURE ? "HQ Picture" :
+           parse_code == VC2_END_OF_SEQUENCE? "End of Sequence" :
+           "Unknown",
+           next_off,
+           prev_off);
+
+    return parse_code;
+}
+
+static int dirac_read_header(AVFormatContext *s)
+{
+    AVDiracSeqHeader *dsh;
+    AVStream *st = avformat_new_stream(s, NULL);
+    int64_t start = avio_tell(s->pb);
+    uint32_t size;
+    uint8_t *buf;
+    int ret;
+
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    while ((ret = parse_header(s, &size)) != VC2_SEQUENCE_HEADER) {
+        if (ret < 0)
+            return ret;
+
+        avio_skip(s->pb, size);
+    }
+
+    if (size > INT_MAX)
+        return AVERROR(ENOSYS);
+
+    if (!(buf = av_malloc(size)))
+        return AVERROR(ENOMEM);
+
+    ret = avio_read(s->pb, buf, size);
+
+    if (ret < 0)
+        goto fail;
+
+    if (ret != size) {
+        ret = AVERROR_EOF;
+        goto fail;
+    }
+
+    ret = av_dirac_parse_sequence_header(&dsh, buf, size, s);
+    if (ret < 0)
+        goto fail;
+
+    st->codecpar->codec_type      = AVMEDIA_TYPE_VIDEO;
+    st->codecpar->codec_id        = AV_CODEC_ID_DIRAC;
+    st->codecpar->width           = dsh->width;
+    st->codecpar->height          = dsh->height;
+    st->codecpar->format          = dsh->pix_fmt;
+    st->codecpar->color_range     = dsh->color_range;
+    st->codecpar->color_trc       = dsh->color_trc;
+    st->codecpar->color_primaries = dsh->color_primaries;
+    st->codecpar->color_space     = dsh->colorspace;
+    st->codecpar->profile         = dsh->profile;
+    st->codecpar->level           = dsh->level;
+
+    avpriv_set_pts_info(st, 64, dsh->framerate.den, dsh->framerate.num);
+
+    av_free(dsh);
+
+    avio_seek(s->pb, start, SEEK_SET);
+
+fail:
+    av_free(buf);
+    return 0;
+}
+
+static int next_header(AVFormatContext *s)
+{
+    uint32_t size = 0;
+    int ret = parse_header(s, &size);
+
+    avio_skip(s->pb, size);
+
+    return ret;
+}
+
+static int dirac_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int64_t pos = avio_tell(s->pb);
+    int64_t end;
+    int ret;
+
+    // TODO resync
+    while ((ret = next_header(s)) != VC2_HQ_PICTURE) {
+        if (ret < 0)
+            return ret;
+    }
+
+    end = avio_tell(s->pb);
+
+    avio_seek(s->pb, pos, SEEK_SET);
+
+    return av_get_packet(s->pb, pkt, end - pos);
+}
+
+AVInputFormat ff_dirac_demuxer = {
+    .name           = "dirac",
+    .long_name      = NULL_IF_CONFIG_SMALL("DRC"),
+    .read_probe     = dirac_probe,
+    .read_header    = dirac_read_header,
+    .read_packet    = dirac_read_packet,
+    .extensions     = "drc,vc2",
+    .raw_codec_id   = AV_CODEC_ID_DIRAC,
+};
-- 
2.9.2

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