avformat/utils: Print verbose error message if stream count exceeds max_streams

Reviewed-by: Andreas Cadhalpun <andreas.cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit f0bdd53871)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -3764,8 +3764,11 @@ AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c)
     int i;
     AVStream **streams;
 
-    if (s->nb_streams >= FFMIN(s->max_streams, INT_MAX/sizeof(*streams)))
+    if (s->nb_streams >= FFMIN(s->max_streams, INT_MAX/sizeof(*streams))) {
+        if (s->max_streams < INT_MAX/sizeof(*streams))
+            av_log(s, AV_LOG_ERROR, "Number of streams exceeds max_streams parameter (%d), see the documentation if you wish to increase it\n", s->max_streams);
         return NULL;
+    }
     streams = av_realloc_array(s->streams, s->nb_streams + 1, sizeof(*streams));
     if (!streams)
         return NULL;