player: store last_time timestamp in nanoseconds

player/core.h

@@ -391,7 +391,7 @@ typedef struct MPContext {
     double start_timestamp;
 
     // Timestamp from the last time some timing functions read the
-    // current time, in microseconds.
+    // current time, in nanoseconds.
     // Used to turn a new time value to a delta from last time.
     int64_t last_time;
 

player/playloop.c

@@ -123,10 +123,10 @@ static void mp_process_input(struct MPContext *mpctx)
 
 double get_relative_time(struct MPContext *mpctx)
 {
-    int64_t new_time = mp_time_us();
+    int64_t new_time = mp_time_ns();
     int64_t delta = new_time - mpctx->last_time;
     mpctx->last_time = new_time;
-    return delta * 0.000001;
+    return delta * 1e-9;
 }
 
 void update_core_idle_state(struct MPContext *mpctx)