avformat: add dvbsub demuxer

This is needed for probing some dvbsub streams in mpegts

Fixes part of ticket4221

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 66 insertions, 0 deletions

diff --git a/libavformat/dvbsub.c b/libavformat/dvbsub.c
new file mode 100644
index 0000000000..73d9c3ef91
--- /dev/null
+++ b/libavformat/dvbsub.c
@@ -0,0 +1,66 @@
+/*
+ * RAW dvbsub demuxer
+ * Copyright (c) 2015 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * 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 "libavutil/intreadwrite.h"
+
+#include "avformat.h"
+#include "rawdec.h"
+
+
+static int dvbsub_probe(AVProbeData *p)
+{
+    int i, j, k;
+    const uint8_t *end = p->buf + p->buf_size;
+    int type, page_id, len;
+    int max_score = 0;
+
+    for(i=0; i<p->buf_size; i++){
+        const uint8_t *ptr = p->buf + i;
+        uint8_t histogram[6] = {0};
+        int min = 255;
+        for(j=0; ptr + 6 < end; j++) {
+            if (*ptr != 0x0f)
+                break;
+            type    = ptr[1];
+            page_id = AV_RB16(ptr + 2);
+            len     = AV_RB16(ptr + 4);
+            if (type == 0x80) {
+                ;
+            } else if (type >= 0x10 && type <= 0x14) {
+                histogram[type - 0x10] ++;
+            } else
+                break;
+            ptr += 6 + len;
+        }
+        for (k=0; k < 4; k++) {
+            min = FFMIN(min, histogram[k]);
+        }
+        if (min && j > max_score)
+            max_score = j;
+    }
+
+    if (max_score > 5)
+        return AVPROBE_SCORE_EXTENSION/2;
+
+    return 0;
+}
+
+FF_DEF_RAWSUB_DEMUXER(dvbsub, "raw dvbsub", dvbsub_probe, NULL, AV_CODEC_ID_DVB_SUBTITLE, AVFMT_GENERIC_INDEX)