Add code for calculating and recognising the interpolation threshold.

player.h

@@ -248,6 +248,7 @@ typedef struct {
   void *dapo_private_storage;  // this is used for compatibility, if dacp stuff isn't enabled.
 
   int enable_dither; // needed for filling silences before play actually starts
+  int64_t dac_buffer_queue_minimum_length;
 } rtsp_conn_info;
 
 uint32_t modulo_32_offset(uint32_t from, uint32_t to);