flvdec: skip duplicate indexes

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

libavformat/flvdec.c

@@ -152,6 +152,11 @@ static int parse_keyframes_index(AVFormatContext *s, AVIOContext *ioc, AVStream
         return 0;
     }
 
+    if(vstream->nb_index_entries>0){
+        av_log(s, AV_LOG_WARNING, "Skiping duplicate index\n");
+        return 0;
+    }
+
     while (avio_tell(ioc) < max_pos - 2 && amf_get_string(ioc, str_val, sizeof(str_val)) > 0) {
         int64_t** current_array;
         unsigned int arraylen;