#include <fcntl.h>
#include <inttypes.h> // PRIdPTR
#include <libgen.h>
+#include <math.h>
#include <memory.h>
#include <poll.h>
#include <popt.h>
}
return vol_setting;
}
+
+double logarithmic_vol2attn(double vol, long max_db, long min_db) {
+ double vol_setting = min_db; // if all else fails, set this, for safety
+
+ if ((vol <= 0.0) && (vol >= -30.0)) {
+ double vol_pct = 1 - (vol / -30.0); // This will be in the range [0, 1]
+ if (vol_pct <= 0) {
+ return min_db;
+ }
+
+ vol_setting = 1000 * log10(vol_pct) / log10(2); // This will be in the range [-inf, 0]
+ if (vol_setting < min_db) {
+ return min_db;
+ }
+ if (vol_setting > max_db) {
+ return max_db;
+ }
+ return vol_setting;
+ } else if (vol != -144.0) {
+ debug(1,
+ "Logarithmic volume request value %f is out of range: should be from 0.0 to -30.0 or -144.0.",
+ vol);
+ }
+ return vol_setting;
+}
+
// Given a volume (0 to -30) and high and low attenuations available in the mixer in dB, return an
// attenuation depending on the volume and the function's transfer function
// See http://tangentsoft.net/audio/atten.html for data on good attenuators.
typedef enum {
VCP_standard = 0,
VCP_flat,
+ VCP_logarithmic,
} volume_control_profile_type;
typedef enum {
// dB), return an attenuation depending on a linear interpolation along along the range
double flat_vol2attn(double vol, long max_db, long min_db);
+// given a volume (0 to -30) and high and low attenuations in dB*100 (e.g. 0 to -6000 for 0 to -60
+// dB), return an attenuation depending on a logarithmic interpolation along along the range
+double logarithmic_vol2attn(double vol, long max_db, long min_db);
+
// given a volume (0 to -30) and high and low attenuations in dB*100 (e.g. 0 to -6000 for 0 to -60
// dB), return an attenuation depending on the transfer function
double vol2attn(double vol, long max_db, long min_db);
config.volume_control_profile = VCP_standard;
else if (strcasecmp(th, "flat") == 0)
config.volume_control_profile = VCP_flat;
+ else if (strcasecmp(th, "logarithmic") == 0)
+ config.volume_control_profile = VCP_logarithmic;
else {
warn("Unrecognised Volume Control Profile: \"%s\".", th);
switch (config.volume_control_profile) {
case VCP_flat:
shairport_sync_set_volume_control_profile(skeleton, "flat");
break;
+ case VCP_logarithmic:
+ shairport_sync_set_volume_control_profile(skeleton, "logarithmic");
+ break;
default:
debug(1, "This should never happen!");
shairport_sync_set_volume_control_profile(skeleton, "standard");
if (config.volume_control_profile == VCP_standard)
shairport_sync_set_volume_control_profile(SHAIRPORT_SYNC(shairportSyncSkeleton), "standard");
+ else if (config.volume_control_profile == VCP_logarithmic)
+ shairport_sync_set_volume_control_profile(SHAIRPORT_SYNC(shairportSyncSkeleton), "logarithmic");
else
shairport_sync_set_volume_control_profile(SHAIRPORT_SYNC(shairportSyncSkeleton), "flat");
else if (config.volume_control_profile == VCP_flat)
scaled_attenuation =
flat_vol2attn(airplay_volume, max_db, min_db); // no cancellation points
+ else if (config.volume_control_profile == VCP_logarithmic)
+ scaled_attenuation =
+ logarithmic_vol2attn(airplay_volume, max_db, min_db); // no cancellation points
else
debug(1, "player_volume_without_notification: unrecognised volume control profile");
}
// 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.
+// "logarithmic" makes the volume change logarithmically.
// volume_control_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.
// default_airplay_volume = -24.0; // this is the suggested volume after a reset or after the high_volume_threshold has been exceed and the high_volume_idle_timeout_in_minutes has passed
config.volume_control_profile = VCP_standard;
else if (strcasecmp(str, "flat") == 0)
config.volume_control_profile = VCP_flat;
+ else if (strcasecmp(str, "logarithmic") == 0)
+ config.volume_control_profile = VCP_logarithmic;
else
- die("Invalid volume_control_profile choice \"%s\". It should be \"standard\" (default) "
- "or \"flat\"",
+ die("Invalid volume_control_profile choice \"%s\". It should be \"standard\" (default), "
+ "\"logarithmic\", or \"flat\"",
str);
}