avformat/mpeg: add missing check

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c
index 0c507e9f01..8ae4740920 100644
--- a/libavformat/mpeg.c
+++ b/libavformat/mpeg.c
@@ -456,6 +456,8 @@ redo:
                 startcode = 0x80;
                 m->raw_ac3 = 1;
                 avio_skip(s->pb, -2);
+            } else {
+                avio_skip(s->pb, -1);
             }
         } else {
             len--;