fix capture latency for ALSA backend, given normal definitions. Add comments

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/alsa/alsa_driver.c b/drivers/alsa/alsa_driver.c
index f190cbd..ca501e3 100644
--- a/drivers/alsa/alsa_driver.c
+++ b/drivers/alsa/alsa_driver.c
@@ -1782,9 +1782,15 @@ alsa_driver_latency_callback (jack_latency_callback_mode_t mode, void* arg)
 
 
 	if (mode == JackPlaybackLatency) {
+		/* Playback latency is defined as the maximum time between the data being delivered to the device buffer and it
+		   emerging from the interface, which is dependent on the number of periods and the period size.
+		*/
 		range.min = range.max = ((driver->playback_nperiods - 1) * driver->frames_per_cycle) + driver->playback_frame_latency;
 	} else {
-		range.min = range.max = ((driver->capture_nperiods - 1) * driver->frames_per_cycle) + driver->capture_frame_latency;
+		/* Input latency is defined as the maximum time between the data arriving at the interface and it becoming available to
+		   the CPU, which is always 1 period
+		*/
+		range.min = range.max = driver->frames_per_cycle + driver->capture_frame_latency;
 	}
 
 	for (node = client->ports; node; node = jack_slist_next (node))