semi-hack: avoid passing 0-length blocks to audio filters.

Fixes bugzilla bug #391 (lavcresample crashes).


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@16816 b3059339-0415-0410-9bf9-f77b7e298cf2

libaf/af.c

@@ -503,6 +503,7 @@ af_data_t* af_play(af_stream_t* s, af_data_t* data)
   af_instance_t* af=s->first; 
   // Iterate through all filters 
   do{
+    if (data->len <= 0) break;
     data=af->play(af,data);
     af=af->next;
   }while(af);