avformat/dvbtxt: add raw demuxer for dvb teletext probing

Signed-off-by: Marton Balint <cus@passwd.hu>

1 files changed, 50 insertions, 0 deletions

diff --git a/libavformat/dvbtxt.c b/libavformat/dvbtxt.c
new file mode 100644
index 0000000000..6828738340
--- /dev/null
+++ b/libavformat/dvbtxt.c
@@ -0,0 +1,50 @@
+/*
+ * RAW dvb teletext demuxer
+ * Copyright (c) 2016 Marton Balnt <cus@passwd.hu>
+ *
+ * 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/dvbtxt.h"
+
+#include "avformat.h"
+#include "rawdec.h"
+
+static int dvbtxt_probe(AVProbeData *p)
+{
+    const uint8_t *end = p->buf + p->buf_size;
+    const uint8_t *buf;
+
+    /* The purpose of this is demuxer is to detect DVB teletext streams in
+     * mpegts, so we reject invalid buffer sizes */
+    if ((p->buf_size + 45) % 184 != 0)
+        return 0;
+
+    if (!ff_data_identifier_is_teletext(p->buf[0]))
+        return 0;
+
+    for (buf = p->buf + 1; buf < end; buf += 46) {
+        if (!ff_data_unit_id_is_teletext(buf[0]) && buf[0] != 0xff)
+            return 0;
+        if (buf[1] != 0x2c)     // data_unit_length
+            return 0;
+    }
+
+    return AVPROBE_SCORE_MAX / 2;
+}
+
+FF_DEF_RAWSUB_DEMUXER(dvbtxt, "dvbtxt", dvbtxt_probe, NULL, AV_CODEC_ID_DVB_TELETEXT, 0)