Basic UI: Reduce audio meter mute timing threshold

Some devices burst their audio (such as when querying audio from
directshow), and the 250 millisecond threshold that sets the audio meter
back to muted status would erroneously cause the meter to appear bounce
back between muted and unmuted.  Instead, a one second test should be
sufficient time to prevent that from happening.

obs/volume-control.cpp

@@ -202,8 +202,7 @@ void VolumeMeter::setLevels(float nmag, float npeak, float npeakHold)
 
 	if (resetTimer->isActive())
 		resetTimer->stop();
-	resetTimer->start(250);
-
+	resetTimer->start(1000);
 }
 
 void VolumeMeter::paintEvent(QPaintEvent *event)