libav: try to fix log crash, fixes #4707

diff --git a/src/libav.c b/src/libav.c
index 5a6b0ea18006309d7913649c7f0141f5ec23fc5c..e8867c49adf47d263578549f6198048e8586553f 100644 (file)
--- a/src/libav.c
+++ b/src/libav.c
@@ -17,7 +17,7 @@ libav_log_callback(void *ptr, int level, const char *fmt, va_list vl)
   if (level != AV_LOG_QUIET &&
       ((level <= AV_LOG_INFO) || (tvhlog_options & TVHLOG_OPT_LIBAV))) {
 
-    class_name = ptr ? av_default_item_name(ptr) : "";
+    class_name = ptr && *(void **)ptr ? av_default_item_name(ptr) : "";
 
     l1 = strlen(fmt);
     l2 = strlen(class_name);