Add code to read audio_backend_silent_lead_in_time settings.

audio_alsa.c

@@ -187,6 +187,19 @@ static int init(int argc, char **argv) {
       }
     }
 
+    /* Get the desired length of the period of silence before the audio starts. */
+    if (config_lookup_float(config.cfg, "alsa.audio_backend_silent_lead_in_time",
+                            &dvalue)) {
+      if ((dvalue < 0.05) || (dvalue > 4)) {
+        pthread_mutex_unlock(&alsa_mutex);
+        die("Invalid alsa audio_backend_silent_lead_in_time \"%f\". It "
+            "must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
+            dvalue);
+      } else {
+        config.audio_backend_silent_lead_in_time = dvalue;
+      }
+    }
+
     /* Get the desired buffer size setting. */
     if (config_lookup_float(config.cfg, "alsa.audio_backend_buffer_desired_length_in_seconds",
                             &dvalue)) {

audio_ao.c

@@ -54,6 +54,19 @@ static int init(int argc, char **argv) {
   // get settings from settings file first, allow them to be overridden by command line options
 
   if (config.cfg != NULL) {
+      /* Get the desired length of the period of silence before the audio starts. */
+    if (config_lookup_float(config.cfg, "ao.audio_backend_silent_lead_in_time",
+                            &dvalue)) {
+      if ((dvalue < 0.05) || (dvalue > 4)) {
+        pthread_mutex_unlock(&alsa_mutex);
+        die("Invalid ao audio_backend_silent_lead_in_time \"%f\". It "
+            "must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
+            dvalue);
+      } else {
+        config.audio_backend_silent_lead_in_time = dvalue;
+      }
+    }
+
     /* Get the desired buffer size setting. */
     if (config_lookup_int(config.cfg, "ao.audio_backend_buffer_desired_length", &value)) {
       if ((value < 0) || (value > 66150)) {

audio_pa.c

@@ -52,6 +52,17 @@ static int init(int argc, char **argv) {
   if (config.cfg != NULL) {
     const char *str;
     double dvalue;
+    /* Get the desired length of the period of silence before the audio starts. */
+    if (config_lookup_float(config.cfg, "pa.audio_backend_silent_lead_in_time",
+                            &dvalue)) {
+      if ((dvalue < 0.05) || (dvalue > 4)) {
+        die("Invalid pa audio_backend_silent_lead_in_time \"%f\". It "
+            "must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
+            dvalue);
+      } else {
+        config.audio_backend_silent_lead_in_time = dvalue;
+      }
+    }
 
     /* Get the desired buffer size setting. */
     if (config_lookup_float(config.cfg, "pa.audio_backend_buffer_desired_length_in_seconds",

audio_pipe.c

@@ -95,6 +95,18 @@ static int init(int argc, char **argv) {
     if (config_lookup_string(config.cfg, "pipe.name", &str)) {
       pipename = (char *)str;
     }
+    
+    /* Get the desired length of the period of silence before the audio starts. */
+    if (config_lookup_float(config.cfg, "pipe.audio_backend_silent_lead_in_time",
+                            &dvalue)) {
+      if ((dvalue < 0.05) || (dvalue > 4)) {
+        die("Invalid pipe audio_backend_silent_lead_in_time \"%f\". It "
+            "must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
+            dvalue);
+      } else {
+        config.audio_backend_silent_lead_in_time = dvalue;
+      }
+    }
 
     if ((pipename) && (strcasecmp(pipename, "STDOUT") == 0))
       die("Can't use \"pipe\" backend for STDOUT. Use the \"stdout\" backend instead.");

audio_stdout.c

@@ -64,6 +64,18 @@ static int init(int argc, char **argv) {
   config.audio_backend_latency_offset = 0;
 
   if (config.cfg != NULL) {
+    /* Get the desired length of the period of silence before the audio starts. */
+    if (config_lookup_float(config.cfg, "stdout.audio_backend_silent_lead_in_time",
+                            &dvalue)) {
+      if ((dvalue < 0.05) || (dvalue > 4)) {
+        die("Invalid stdout audio_backend_silent_lead_in_time \"%f\". It "
+            "must be between 0.050 and 4.0 seconds. Omit setting to use the default value, which is approximately the latency specified by the source (typically 2 seconds). A value greater than the latency is ignored.",
+            dvalue);
+      } else {
+        config.audio_backend_silent_lead_in_time = dvalue;
+      }
+    }
+
     /* Get the desired buffer size setting. */
     if (config_lookup_int(config.cfg, "stdout.audio_backend_buffer_desired_length", &value)) {
       if ((value < 0) || (value > 66150)) {

shairport.c

@@ -1316,6 +1316,7 @@ int main(int argc, char **argv) {
   debug(1, "audio backend desired buffer length is %f seconds.",
         config.audio_backend_buffer_desired_length);
   debug(1, "audio backend latency offset is %f seconds.", config.audio_backend_latency_offset);
+  debug(1, "audio backend silence lead-in time is %f seconds. The value -1.0 means use the default.", config.audio_backend_silent_lead_in_time);
   debug(1, "volume range in dB (zero means use the range specified by the mixer): %u.",
         config.volume_range_db);
   debug(1, "zeroconf regtype is \"%s\".", config.regtype);