gistfile1.diff

diff --git a/libavformat/utils.c b/libavformat/utils.c
index b992923..87052af 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2483,6 +2483,23 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
         count++;
     }
 
+    /* try to open decoders for all streams if not opened already */
+    for (i = 0; i < ic->nb_streams; i++) {
+        st = ic->streams[i];
+        if (!has_codec_parameters(st) &&
+            !avcodec_is_open(st->codec) && !st->info->found_decoder) {
+            pkt1.size = 0;
+            pkt1.data = NULL;
+            av_init_packet(&pkt1);
+            try_decode_frame(st, &pkt1,
+                             (options && i < orig_nb_streams) ? &options[i] : NULL);
+        }
+        if (!has_codec_parameters(st)) {
+            av_log(ic, AV_LOG_WARNING,
+                   "codec parameters not found for stream %d\n", i);
+        }
+    }
+
     // close codecs which were opened in try_decode_frame()
     for(i=0;i<ic->nb_streams;i++) {
         st = ic->streams[i];