use CLOCK_REALTIME instead of CLOCK_MONOTONIC is the alsa library is older than 1.0.28.

audio_alsa.c

@@ -114,7 +114,6 @@ int frame_size; // in bytes for interleaved stereo
 int alsa_device_initialised; // boolean to ensure the initialisation is only
                              // done once
 snd_pcm_t *alsa_handle = NULL;
-int alsa_uses_monotonic_clock = 0;
 static snd_pcm_hw_params_t *alsa_params = NULL;
 static snd_pcm_sw_params_t *alsa_swparams = NULL;
 static snd_ctl_t *ctl = NULL;
@@ -458,12 +457,6 @@ int actual_open_alsa_device(void) {
          snd_strerror(ret));
     return ret;
   }
-  
-  alsa_uses_monotonic_clock = snd_pcm_hw_params_is_monotonic(alsa_params);	
-  debug(1,"alsa_uses_monotonic_clock is %d",alsa_uses_monotonic_clock);
-  
-  debug (1,"sizeof time_t is: %d.", sizeof(time_t));
-  debug (1,"sizeof long is: %d.", sizeof(long));
 
   ret = snd_pcm_sw_params_current(alsa_handle, alsa_swparams);
   if (ret < 0) {
@@ -1158,7 +1151,14 @@ int delay_and_status(snd_pcm_state_t *state, snd_pcm_sframes_t *delay) {
       if (*state == SND_PCM_STATE_DRAINING)
         debug(1, "alsa: draining with a delay of %d.", delay);
 
+// It seems that the alsa library uses CLOCK_REALTIME before 1.0.28, even though
+// the check for monotonic returns true. Might have to watch out for this.
+#if SND_LIB_MINOR == 0 && SND_LIB_SUBMINOR < 28
+      clock_gettime(CLOCK_REALTIME, &tn);
+#else
       clock_gettime(CLOCK_MONOTONIC, &tn);
+#endif
+    
       uint64_t time_now_ns = tn.tv_sec * (uint64_t)1000000000 + tn.tv_nsec;
       uint64_t update_timestamp_ns =
           update_timestamp.tv_sec * (uint64_t)1000000000 + update_timestamp.tv_nsec;

scripts/shairport-sync.conf

@@ -29,7 +29,7 @@ general =
 //	volume_control_profile = "standard" ; // use this advanced setting to specify how the airplay volume is transferred to the mixer volume.
 //		"standard" makes the volume change more quickly at lower volumes and slower at higher volumes.
 //		"flat" makes the volume change at the same rate at all volumes.
-//	volume_range_hw_priority = "yes"; // when extending the volume range by combining the built-in software attenuator with the hardware mixer attenuator, set this to "yes" to reduce volume by using the hardware attenuator first, then the software attenuator.
+//	volume_range_combined_hardware_priority = "no"; // when extending the volume range by combining the built-in software attenuator with the hardware mixer attenuator, set this to "yes" to reduce volume by using the hardware mixer first, then the built-in software attenuator. 
 //	run_this_when_volume_is_set = "/full/path/to/application/and/args"; //	Run the specified application whenever the volume control is set or changed.
 //		The desired AirPlay volume is appended to the end of the command line – leave a space if you want it treated as an extra argument.
 //		AirPlay volume goes from 0 to -30 and -144 means "mute".

shairport.c

@@ -344,8 +344,9 @@ int parse_options(int argc, char **argv) {
   config.diagnostic_drop_packet_fraction = 0.0;
   config.active_state_timeout = 10.0;
   config.volume_range_hw_priority =
-      1; // if combining software and hardware volume control, give the hardware priority
-// i.e. when reducing volume, reduce the hw first before reducing the software.
+      0; // if combining software and hardware volume control, give the software priority
+// i.e. when reducing volume, reduce the sw first before reducing the software.
+// this is because some hw mixers mute at the bottom of their range, and they don't always advertise this fact
 
 #ifdef CONFIG_METADATA_HUB
   config.cover_art_cache_dir = "/tmp/shairport-sync/.cache/coverart";
@@ -1568,7 +1569,7 @@ int main(int argc, char **argv) {
         config.volume_range_db);
   debug(
       1,
-      "combined attenuators (0 -- software is / 1 -- hardware is top of attenuation range) is %d.",
+      "volume_range_combined_hardware_priority (1 means hardware mixer attenuation is used first) is %d.",
       config.volume_range_hw_priority);
   debug(1, "playback_mode is %d (0-stereo, 1-mono, 1-reverse_stereo, 2-both_left, 3-both_right).",
         config.playback_mode);