Adding audio buffer size to preferences, with reasonable default limits (128-4096). 512 should be a good default for most systems. This will allow users to customize how much audio buffer must be filled prior to audio playback for their systems. Updating docs also, with a description of this setting.

Author: jonoomph

doc/preferences.rst

@@ -99,7 +99,8 @@ real-time preview audio settings, for example, which audio device and sample rat
    ================================  ==================  ===========
    Setting                           Default             Description
    ================================  ==================  ===========
-   Default Video Profile             HD 720P 30 fps      Select the profile for Preview and Export defaults  
+   Default Video Profile             HD 720P 30 fps      Select the profile for Preview and Export defaults
+   Playback Audio Buffer Size        512                 Adjust how many audio samples must be buffered before audio playback begins. Allowed range of values is 128 to 4096. NOTE: If you are experiencing a large drift or delay in audio playback, try setting this value lower.
    Playback Audio Device             Default             
    Default Audio Sample Rate         44100               
    Default Audio Channels            Stereo (2 Channel)  

src/settings/_default.settings

@@ -138,6 +138,16 @@
     "values": [],
     "restart": true
   },
+  {
+    "min": 128,
+    "max": 4096,
+    "value": 512,
+    "title": "Playback Audio Buffer Size",
+    "category": "Preview",
+    "setting": "playback-buffer-size",
+    "type": "spinner-int",
+    "restart": true
+  },
   {
     "value": "",
     "title": "Playback Audio Device",

src/windows/main_window.py

@@ -3675,6 +3675,7 @@ def __init__(self, *args):
         # - OLD settings only includes device name (i.e. "PulseAudio Sound Server")
         # - NEW settings include both device name and type (double pipe delimited)
         #   (i.e. "PulseAudio Sound Server||ALSA")
+        playback_buffer_size = s.get("playback-buffer-size") or 512
         playback_device_value = s.get("playback-audio-device") or ""
         playback_device_parts = playback_device_value.split("||")
         playback_device_name = playback_device_parts[0]
@@ -3685,6 +3686,7 @@ def __init__(self, *args):
         # Set libopenshot settings
         lib_settings.PLAYBACK_AUDIO_DEVICE_NAME = playback_device_name
         lib_settings.PLAYBACK_AUDIO_DEVICE_TYPE = playback_device_type
+        lib_settings.PLAYBACK_AUDIO_BUFFER_SIZE = playback_buffer_size
 
         # Set scaling mode to lower quality scaling (for faster previews)
         lib_settings.HIGH_QUALITY_SCALING = False