avformat: add SUP/PGS subtitle demuxer

Signed-off-by: Clément Bœsch <u@pkh.me>

1 files changed, 109 insertions, 0 deletions

diff --git a/libavformat/supdec.c b/libavformat/supdec.c
new file mode 100644
index 0000000000..48083b2c53
--- /dev/null
+++ b/libavformat/supdec.c
@@ -0,0 +1,109 @@
+/*
+ * 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 "avformat.h"
+#include "internal.h"
+#include "libavutil/intreadwrite.h"
+
+#define SUP_PGS_MAGIC 0x5047 /* "PG", big endian */
+
+static int sup_read_header(AVFormatContext *s)
+{
+    AVStream *st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+    st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
+    st->codec->codec_id = AV_CODEC_ID_HDMV_PGS_SUBTITLE;
+    avpriv_set_pts_info(st, 32, 1, 90000);
+
+    return 0;
+}
+
+static int sup_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int64_t pts, dts, pos;
+    int ret;
+
+    pos = avio_tell(s->pb);
+
+    if (avio_rb16(s->pb) != SUP_PGS_MAGIC)
+        return avio_feof(s->pb) ? AVERROR_EOF : AVERROR_INVALIDDATA;
+
+    pts = avio_rb32(s->pb);
+    dts = avio_rb32(s->pb);
+
+    if ((ret = av_get_packet(s->pb, pkt, 3)) < 0)
+        return ret;
+
+    pkt->stream_index = 0;
+    pkt->flags |= AV_PKT_FLAG_KEY;
+    pkt->pos = pos;
+    pkt->pts = pts;
+    // Many files have DTS set to 0 for all packets, so assume 0 means unset.
+    pkt->dts = dts ? dts : AV_NOPTS_VALUE;
+
+    if (pkt->size >= 3) {
+        // The full packet size is stored as part of the packet.
+        size_t len = AV_RB16(pkt->data + 1);
+
+        if ((ret = av_append_packet(s->pb, pkt, len)) < 0)
+            return ret;
+    }
+
+    return 0;
+}
+
+static int sup_probe(AVProbeData *p)
+{
+    unsigned char *buf = p->buf;
+    size_t buf_size = p->buf_size;
+    int nb_packets;
+
+    for (nb_packets = 0; nb_packets < 10; nb_packets++) {
+        size_t full_packet_size;
+        if (buf_size < 10 + 3)
+            break;
+        if (AV_RB16(buf) != SUP_PGS_MAGIC)
+            return 0;
+        full_packet_size = AV_RB16(buf + 10 + 1) + 10 + 3;
+        if (buf_size < full_packet_size)
+            break;
+        buf += full_packet_size;
+        buf_size -= full_packet_size;
+    }
+    if (!nb_packets)
+        return 0;
+    if (nb_packets < 2)
+        return AVPROBE_SCORE_RETRY / 2;
+    if (nb_packets < 4)
+        return AVPROBE_SCORE_RETRY;
+    if (nb_packets < 10)
+        return AVPROBE_SCORE_EXTENSION;
+    return AVPROBE_SCORE_MAX;
+}
+
+AVInputFormat ff_sup_demuxer = {
+    .name           = "sup",
+    .long_name      = NULL_IF_CONFIG_SMALL("raw HDMV Presentation Graphic Stream subtitles"),
+    .extensions     = "sup",
+    .mime_type      = "application/x-pgs",
+    .read_probe     = sup_probe,
+    .read_header    = sup_read_header,
+    .read_packet    = sup_read_packet,
+    .flags          = AVFMT_GENERIC_INDEX,
+};