This patch is purely cosmetic. It changes debugging output to a be better readable
and tracks the prediction error for debugging purpose only. The patch also adds
Georg Chini to the authors of the module.
---
src/modules/module-loopback.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
diff --git a/src/modules/module-loopback.c b/src/modules/module-loopback.c
index 29d43ca..a31ab58 100644
--- a/src/modules/module-loopback.c
+++ b/src/modules/module-loopback.c
@@ -38,7 +38,7 @@
#include "module-loopback-symdef.h"
-PA_MODULE_AUTHOR("Pierre-Louis Bossart");
+PA_MODULE_AUTHOR("Pierre-Louis Bossart, Georg Chini");
PA_MODULE_DESCRIPTION("Loopback from source to sink");
PA_MODULE_VERSION(PACKAGE_VERSION);
PA_MODULE_LOAD_ONCE(false);
@@ -117,9 +117,10 @@ struct userdata {
double drift_filter;
double drift_compensation_rate;
- /* Variables for Kalman filter */
+ /* Variables for Kalman filter and error tracking*/
double latency_variance;
double kalman_variance;
+ double latency_error;
/* lower latency limit found by underruns */
pa_usec_t underrun_latency_limit;
@@ -461,6 +462,8 @@ static void adjust_rates(struct userdata *u) {
u->next_latency_at_optimum_rate_with_drift += u->sink_latency_offset - u->last_sink_latency_offset;
u->next_latency_with_drift += u->source_latency_offset - u->last_source_latency_offset;
u->next_latency_with_drift += u->sink_latency_offset - u->last_sink_latency_offset;
+ /* Low pass filtered latency error. This value reflects how well the measured values match the prediction. */
+ u->latency_error = (1 - FILTER_PARAMETER) * u->latency_error + FILTER_PARAMETER * (double)abs((int32_t)(current_latency - u->next_latency_with_drift));
/* Low pass filtered latency variance */
current_latency_error = (double)abs((int32_t)(latency_at_optimum_rate - u->next_latency_at_optimum_rate_with_drift));
u->latency_variance = (1.0 - FILTER_PARAMETER) * u->latency_variance + FILTER_PARAMETER * current_latency_error * current_latency_error;
@@ -469,17 +472,22 @@ static void adjust_rates(struct userdata *u) {
u->kalman_variance = u->kalman_variance * u->latency_variance / (u->kalman_variance + u->latency_variance) + u->latency_variance / 4 + 200;
}
- pa_log_debug("Loopback overall latency is %0.2f ms + %0.2f ms + %0.2f ms = %0.2f ms",
- (double) u->latency_snapshot.sink_latency / PA_USEC_PER_MSEC,
- (double) current_buffer_latency / PA_USEC_PER_MSEC,
- (double) u->latency_snapshot.source_latency / PA_USEC_PER_MSEC,
- (double) current_latency / PA_USEC_PER_MSEC);
-
- pa_log_debug("Loopback latency at optimum rate is %0.2f ms", (double)latency_at_optimum_rate / PA_USEC_PER_MSEC);
-
/* Calculate new rate */
new_rate = rate_controller(u, base_rate, old_rate, (int32_t)(filtered_latency - final_latency), latency_difference);
+ pa_log_debug("Loopback status %s to %s:\n Source latency: %0.2f ms\n Buffer: %0.2f ms\n Sink latency: %0.2f ms\n End-to-end latency: %0.2f ms\n"
+ " Deviation from target latency at optimum rate: %0.2f usec\n Average prediction error: ± %0.2f usec\n Optimum rate: %0.2f Hz\n Deviation from base rate: %i Hz",
+ u->source_output->source->name,
+ u->sink_input->sink->name,
+ (double) u->latency_snapshot.source_latency / PA_USEC_PER_MSEC,
+ (double) current_buffer_latency / PA_USEC_PER_MSEC,
+ (double) u->latency_snapshot.sink_latency / PA_USEC_PER_MSEC,
+ (double) current_latency / PA_USEC_PER_MSEC,
+ (double) latency_at_optimum_rate - final_latency,
+ (double) u->latency_error,
+ u->drift_compensation_rate + base_rate,
+ (int32_t)(new_rate - base_rate));
+
/* Save current latency difference at new rate for next cycle and reset flags */
u->last_latency_difference = current_source_sink_latency + current_buffer_latency * old_rate / new_rate - final_latency;
@@ -517,7 +525,6 @@ static void adjust_rates(struct userdata *u) {
/* Set rate */
pa_sink_input_set_rate(u->sink_input, new_rate);
- pa_log_debug("[%s] Updated sampling rate to %lu Hz.", u->sink_input->sink->name, (unsigned long) new_rate);
}
/* Called from main context */
@@ -843,9 +850,11 @@ static void source_output_moving_cb(pa_source_output *o, pa_source *dest) {
u->iteration_counter = 0;
u->underrun_counter = 0;
+ /* Reset booleans and latency error */
u->source_sink_changed = true;
u->underrun_occured = false;
u->source_latency_offset_changed = false;
+ u->latency_error = 0;
/* Send a mesage to the output thread that the source and offset have changed.
* If the sink is invalid here during a profile switching situation
@@ -1243,9 +1252,11 @@ static void sink_input_moving_cb(pa_sink_input *i, pa_sink *dest) {
u->iteration_counter = 0;
u->underrun_counter = 0;
+ /* Reset booleans and latency error */
u->source_sink_changed = true;
u->underrun_occured = false;
u->sink_latency_offset_changed = false;
+ u->latency_error = 0;
/* Send a message to the output thread that the sink and offset have changed */
pa_asyncmsgq_send(dest->asyncmsgq, PA_MSGOBJECT(u->sink_input), SINK_INPUT_MESSAGE_SINK_CHANGED, NULL, 0, NULL);
@@ -1527,6 +1538,7 @@ int pa__init(pa_module *m) {
u->underrun_occured = false;
u->source_latency_offset_changed = false;
u->sink_latency_offset_changed = false;
+ u->latency_error = 0;
u->initial_adjust_pending = true;
adjust_time_sec = DEFAULT_ADJUST_TIME_USEC / PA_USEC_PER_SEC;
--
2.10.1
