Add support for setting the default volume smooth time for sounds.

This is set via the engine config.

miniaudio.h

@@ -11115,27 +11115,28 @@ MA_API ma_sound_group_config ma_sound_group_config_init_2(ma_engine* pEngine);
 typedef struct
 {
 #if !defined(MA_NO_RESOURCE_MANAGER)
-    ma_resource_manager* pResourceManager;      /* Can be null in which case a resource manager will be created for you. */
+    ma_resource_manager* pResourceManager;          /* Can be null in which case a resource manager will be created for you. */
 #endif
 #if !defined(MA_NO_DEVICE_IO)
     ma_context* pContext;
-    ma_device* pDevice;                         /* If set, the caller is responsible for calling ma_engine_data_callback() in the device's data callback. */
-    ma_device_id* pPlaybackDeviceID;            /* The ID of the playback device to use with the default listener. */
+    ma_device* pDevice;                             /* If set, the caller is responsible for calling ma_engine_data_callback() in the device's data callback. */
+    ma_device_id* pPlaybackDeviceID;                /* The ID of the playback device to use with the default listener. */
     ma_device_notification_proc notificationCallback;
 #endif
-    ma_log* pLog;                               /* When set to NULL, will use the context's log. */
-    ma_uint32 listenerCount;                    /* Must be between 1 and MA_ENGINE_MAX_LISTENERS. */
-    ma_uint32 channels;                         /* The number of channels to use when mixing and spatializing. When set to 0, will use the native channel count of the device. */
-    ma_uint32 sampleRate;                       /* The sample rate. When set to 0 will use the native channel count of the device. */
-    ma_uint32 periodSizeInFrames;               /* If set to something other than 0, updates will always be exactly this size. The underlying device may be a different size, but from the perspective of the mixer that won't matter.*/
-    ma_uint32 periodSizeInMilliseconds;         /* Used if periodSizeInFrames is unset. */
-    ma_uint32 gainSmoothTimeInFrames;           /* The number of frames to interpolate the gain of spatialized sounds across. If set to 0, will use gainSmoothTimeInMilliseconds. */
-    ma_uint32 gainSmoothTimeInMilliseconds;     /* When set to 0, gainSmoothTimeInFrames will be used. If both are set to 0, a default value will be used. */
+    ma_log* pLog;                                   /* When set to NULL, will use the context's log. */
+    ma_uint32 listenerCount;                        /* Must be between 1 and MA_ENGINE_MAX_LISTENERS. */
+    ma_uint32 channels;                             /* The number of channels to use when mixing and spatializing. When set to 0, will use the native channel count of the device. */
+    ma_uint32 sampleRate;                           /* The sample rate. When set to 0 will use the native channel count of the device. */
+    ma_uint32 periodSizeInFrames;                   /* If set to something other than 0, updates will always be exactly this size. The underlying device may be a different size, but from the perspective of the mixer that won't matter.*/
+    ma_uint32 periodSizeInMilliseconds;             /* Used if periodSizeInFrames is unset. */
+    ma_uint32 gainSmoothTimeInFrames;               /* The number of frames to interpolate the gain of spatialized sounds across. If set to 0, will use gainSmoothTimeInMilliseconds. */
+    ma_uint32 gainSmoothTimeInMilliseconds;         /* When set to 0, gainSmoothTimeInFrames will be used. If both are set to 0, a default value will be used. */
+    ma_uint32 defaultVolumeSmoothTimeInPCMFrames;   /* Defaults to 0. Controls the default amount of smoothing to apply to volume changes to sounds. High values means more smoothing at the expense of high latency (will take longer to reach the new volume). */
     ma_allocation_callbacks allocationCallbacks;
-    ma_bool32 noAutoStart;                      /* When set to true, requires an explicit call to ma_engine_start(). This is false by default, meaning the engine will be started automatically in ma_engine_init(). */
-    ma_bool32 noDevice;                         /* When set to true, don't create a default device. ma_engine_read_pcm_frames() can be called manually to read data. */
-    ma_mono_expansion_mode monoExpansionMode;   /* Controls how the mono channel should be expanded to other channels when spatialization is disabled on a sound. */
-    ma_vfs* pResourceManagerVFS;                /* A pointer to a pre-allocated VFS object to use with the resource manager. This is ignored if pResourceManager is not NULL. */
+    ma_bool32 noAutoStart;                          /* When set to true, requires an explicit call to ma_engine_start(). This is false by default, meaning the engine will be started automatically in ma_engine_init(). */
+    ma_bool32 noDevice;                             /* When set to true, don't create a default device. ma_engine_read_pcm_frames() can be called manually to read data. */
+    ma_mono_expansion_mode monoExpansionMode;       /* Controls how the mono channel should be expanded to other channels when spatialization is disabled on a sound. */
+    ma_vfs* pResourceManagerVFS;                    /* A pointer to a pre-allocated VFS object to use with the resource manager. This is ignored if pResourceManager is not NULL. */
 } ma_engine_config;
 
 MA_API ma_engine_config ma_engine_config_init(void);
@@ -11161,6 +11162,7 @@ struct ma_engine
     ma_sound_inlined* pInlinedSoundHead;        /* The first inlined sound. Inlined sounds are tracked in a linked list. */
     MA_ATOMIC(4, ma_uint32) inlinedSoundCount;  /* The total number of allocated inlined sound objects. Used for debugging. */
     ma_uint32 gainSmoothTimeInFrames;           /* The number of frames to interpolate the gain of spatialized sounds across. */
+    ma_uint32 defaultVolumeSmoothTimeInPCMFrames;
     ma_mono_expansion_mode monoExpansionMode;
 };
 
@@ -74359,6 +74361,7 @@ MA_API ma_result ma_engine_init(const ma_engine_config* pConfig, ma_engine* pEng
     }
 
     pEngine->monoExpansionMode = engineConfig.monoExpansionMode;
+    pEngine->defaultVolumeSmoothTimeInPCMFrames = engineConfig.defaultVolumeSmoothTimeInPCMFrames;
     ma_allocation_callbacks_init_copy(&pEngine->allocationCallbacks, &engineConfig.allocationCallbacks);
 
     #if !defined(MA_NO_RESOURCE_MANAGER)
@@ -75179,6 +75182,10 @@ static ma_result ma_sound_init_from_data_source_internal(ma_engine* pEngine, con
     engineNodeConfig.volumeSmoothTimeInPCMFrames = pConfig->volumeSmoothTimeInPCMFrames;
     engineNodeConfig.monoExpansionMode           = pConfig->monoExpansionMode;
 
+    if (engineNodeConfig.volumeSmoothTimeInPCMFrames == 0) {
+        engineNodeConfig.volumeSmoothTimeInPCMFrames = pEngine->defaultVolumeSmoothTimeInPCMFrames;
+    }
+
     /* If we're loading from a data source the input channel count needs to be the data source's native channel count. */
     if (pConfig->pDataSource != NULL) {
         result = ma_data_source_get_data_format(pConfig->pDataSource, NULL, &engineNodeConfig.channelsIn, &engineNodeConfig.sampleRate, NULL, 0);