avformat/dtsdec: Improve probe, reject things looking like analog signals

Fixes Ticket2810

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 6663205338f57eedb2392263dde48e2717c6e980)

Conflicts:
	libavformat/dtsdec.c

1 files changed, 6 insertions, 1 deletions

diff --git a/libavformat/dtsdec.c b/libavformat/dtsdec.c
index 5c05758327..009dd5c456 100644
--- a/libavformat/dtsdec.c
+++ b/libavformat/dtsdec.c
@@ -34,6 +34,7 @@ static int dts_probe(AVProbeData *p)
     uint32_t state = -1;
     int markers[3] = {0};
     int sum, max;
+    int64_t diff = 0;
 
     buf = p->buf;
 
@@ -54,12 +55,16 @@ static int dts_probe(AVProbeData *p)
         if (state == DCA_MARKER_14B_LE)
             if ((bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
                 markers[2]++;
+
+        if (buf - p->buf >= 4)
+            diff += FFABS(AV_RL16(buf) - AV_RL16(buf-4));
     }
     sum = markers[0] + markers[1] + markers[2];
     max = markers[1] > markers[0];
     max = markers[2] > markers[max] ? 2 : max;
     if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
-        markers[max] * 4 > sum * 3)
+        markers[max] * 4 > sum * 3 &&
+        diff / p->buf_size > 200)
         return AVPROBE_SCORE_MAX/2+1;
 
     return 0;