[FFmpeg-cvslog] lavf/vc1dec: Reduce probe score for streams with invalid frames.

[Carl Eugen Hoyos]

ffmpeg | branch: master | Carl Eugen Hoyos <ceffmpeg at gmail.com> | Fri Apr 19 14:06:29 2019 +0200| [32215b21407e2587af5fb24b4b67470d23852598] | committer: Carl Eugen Hoyos

lavf/vc1dec: Reduce probe score for streams with invalid frames.

Fixes ticket #7853.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=32215b21407e2587af5fb24b4b67470d23852598
---

 libavformat/vc1dec.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/libavformat/vc1dec.c b/libavformat/vc1dec.c
index f4101ae594..fdbb05d6d8 100644
--- a/libavformat/vc1dec.c
+++ b/libavformat/vc1dec.c
@@ -26,7 +26,7 @@
 
 static int vc1_probe(const AVProbeData *p)
 {
-    int seq = 0, entry = 0, frame = 0, i;
+    int seq = 0, entry = 0, invalid = 0, frame = 0, i;
 
     for (i = 0; i < p->buf_size + 5; i++) {
         uint32_t code = AV_RB32(p->buf + i);
@@ -39,16 +39,19 @@ static int vc1_probe(const AVProbeData *p)
                 profile = (p->buf[i] & 0xc0) >> 6;
                 if (profile != PROFILE_ADVANCED) {
                     seq = 0;
+                    invalid++;
                     continue;
                 }
                 level = (p->buf[i] & 0x38) >> 3;
                 if (level >= 5) {
                     seq = 0;
+                    invalid++;
                     continue;
                 }
                 chromaformat = (p->buf[i] & 0x6) >> 1;
                 if (chromaformat != 1) {
                     seq = 0;
+                    invalid++;
                     continue;
                 }
                 seq++;
@@ -56,8 +59,10 @@ static int vc1_probe(const AVProbeData *p)
                 break;
             }
             case VC1_CODE_ENTRYPOINT:
-                if (!seq)
+                if (!seq) {
+                    invalid++;
                     continue;
+                }
                 entry++;
                 i += 2;
                 break;
@@ -71,9 +76,9 @@ static int vc1_probe(const AVProbeData *p)
         }
     }
 
-    if (frame > 1)
+    if (frame > 1 && frame >> 1 > invalid)
         return AVPROBE_SCORE_EXTENSION / 2 + 1;
-    if (frame == 1)
+    if (frame >= 1)
         return AVPROBE_SCORE_EXTENSION / 4;
     return 0;
 }