From: Mike Brady <mikebrady@eircom.net>
Date: Mon, 17 Sep 2018 18:14:38 +0000 (+0100)
Subject: Ignore the latency of whatever is connected to Shairport Sync. It's inappropriate... 
X-Git-Tag: 3.3RC0~219
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c1d5815c49fde127845d2bc7420d9d7f72a22ce2;p=thirdparty%2Fshairport-sync.git

Ignore the latency of whatever is connected to Shairport Sync. It's inappropriate to try to compensate for the latency in the full jack chain. Don't mute when the latency is zero.
---

diff --git a/audio_jack.c b/audio_jack.c
index e27c5884..2f79bee1 100644
--- a/audio_jack.c
+++ b/audio_jack.c
@@ -49,7 +49,7 @@ size_t audio_occupancy; // this is in frames, not bytes. A frame is a left and
                         // right sample, each 16 bits, hence 4 bytes
 pthread_t *open_client_if_necessary_thread = NULL;
 
-int init(int, char **);
+int jack_init(int, char **);
 void jack_deinit(void);
 void jack_start(int, int);
 int play(void *, int);
@@ -60,7 +60,7 @@ void jack_flush(void);
 
 audio_output audio_jack = {.name = "jack",
                            .help = NULL,
-                           .init = &init,
+                           .init = &jack_init,
                            .deinit = &jack_deinit,
                            .start = &jack_start,
                            .stop = &jack_stop,
@@ -80,6 +80,7 @@ long offset = 0;
 int client_is_open;
 jack_client_t *client;
 jack_nframes_t sample_rate;
+jack_nframes_t jack_latency;
 
 jack_latency_range_t latest_left_latency_range, latest_right_latency_range;
 int64_t time_of_latest_transfer;
@@ -192,6 +193,23 @@ void default_jack_error_callback(const char *desc) { debug(2, "jackd error: \"%s
 
 void default_jack_info_callback(const char *desc) { inform("jackd information: \"%s\"", desc); }
 
+void default_jack_set_latency_callback(jack_latency_callback_mode_t mode,
+                                       __attribute__((unused)) void *arg) {
+  if (mode == JackPlaybackLatency) {
+    jack_latency_range_t left_latency_range, right_latency_range;
+    jack_port_get_latency_range(left_port, JackPlaybackLatency, &left_latency_range);
+    jack_port_get_latency_range(right_port, JackPlaybackLatency, &right_latency_range);
+
+    jack_nframes_t b_latency = (left_latency_range.min + left_latency_range.max) / 2;
+    if (b_latency == 0)
+      b_latency = (right_latency_range.min + right_latency_range.max) / 2;
+    // jack_latency = b_latency; // actually, we are not interested in the latency of the jack
+    // devices connected...
+    jack_latency = 0;
+    debug(1, "playback latency callback: %" PRIu32 ".", jack_latency);
+  }
+}
+
 int jack_is_running() {
   int reply = -1; // meaning jack is not running
   // if the client is open and initialised, see if the status is "rolling"
@@ -203,12 +221,12 @@ int jack_is_running() {
     jack_port_get_latency_range(left_port, JackPlaybackLatency, &left_latency_range);
     jack_port_get_latency_range(right_port, JackPlaybackLatency, &right_latency_range);
 
-    if ((left_latency_range.min == 0) && (left_latency_range.max == 0) &&
-        (right_latency_range.min == 0) && (right_latency_range.max == 0)) {
-      reply = -2; // meaning Shairport Sync is not connected
-    } else {
-      reply = 0; // meaning jack is open and Shairport Sync is connected to it
-    }
+    //    if ((left_latency_range.min == 0) && (left_latency_range.max == 0) &&
+    //        (right_latency_range.min == 0) && (right_latency_range.max == 0)) {
+    //      reply = -2; // meaning Shairport Sync is not connected
+    //    } else {
+    reply = 0; // meaning jack is open and Shairport Sync is connected to it
+               //    }
   }
   return reply;
 }
@@ -227,11 +245,15 @@ int jack_client_open_if_needed(void) {
       sample_rate = jack_get_sample_rate(client);
       // debug(1, "jackaudio sample rate = %" PRId32 ".", sample_rate);
       if (sample_rate == 44100) {
-        if (jack_activate(client)) {
-          debug(1, "jackaudio cannot activate client");
+        if (jack_set_latency_callback(client, default_jack_set_latency_callback, NULL) == 0) {
+          if (jack_activate(client)) {
+            debug(1, "jackaudio cannot activate client");
+          } else {
+            debug(2, "jackaudio client opened.");
+            client_is_open = 1;
+          }
         } else {
-          client_is_open = 1;
-          debug(2, "jackaudio client opened.");
+          debug(1, "jackaudio cannot set latency callback");
         }
       } else {
         inform(
@@ -276,7 +298,7 @@ void *open_client_if_necessary_thread_function(void *arg) {
   pthread_exit(NULL);
 }
 
-int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
+int jack_init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
   config.audio_backend_latency_offset = 0;
   config.audio_backend_buffer_desired_length = 0.500;
   config.jack_auto_client_open_interval = 1; // check every second