Log average latency in pulse input

This adds another statistics counter to the pulse plugin in order
to print the average latency reported by pulse when the source is
destroyed.

plugins/linux-pulseaudio/pulse-input.c

@@ -41,6 +41,7 @@ struct pulse_data {
 	/* statistics */
 	uint_fast32_t packets;
 	uint_fast64_t frames;
+	double latency;
 };
 
 static void pulse_stop_recording(struct pulse_data *data);
@@ -150,6 +151,7 @@ static void pulse_stream_read(pa_stream *p, size_t nbytes, void *userdata)
 
 	data->packets++;
 	data->frames += out.frames;
+	data->latency += latency;
 
 	pa_stream_drop(data->stream);
 exit:
@@ -278,11 +280,16 @@ static void pulse_stop_recording(struct pulse_data *data)
 		pulse_unlock();
 	}
 
+	data->latency /= (double) data->packets * 1000.0;
+
 	blog(LOG_INFO, "Stopped recording from '%s'", data->device);
 	blog(LOG_INFO, "Got %"PRIuFAST32" packets with %"PRIuFAST64" frames",
 		data->packets, data->frames);
+	blog(LOG_INFO, "Average latency: %.2f msec", data->latency);
+
 	data->packets = 0;
 	data->frames = 0;
+	data->latency = 0.0;
 }
 
 /**