Change the default ASIO buffer size from 20 ms to 40 ms.

DirectSound is unable to achieve a read cursor granularity lower
than ~30 ms on the input side, which means the default 20 ms buffer
size simply cannot work properly with the default backend.

Fixes #29 #30.

CONFIGURATION.md

@@ -128,7 +128,7 @@ bufferSizeSamples = 480 # 10 ms at 48 kHz
 ```
 
 The default behaviour is to advertise minimum, preferred and maximum buffer
-sizes of 1 ms, 20 ms and 1 s, respectively. The resulting sizes in samples are
+sizes of 1 ms, 40 ms and 1 s, respectively. The resulting sizes in samples are
 computed based on whatever sample rate the driver is set to when the application
 enquires.
 

README.md

@@ -49,7 +49,7 @@ The default settings are as follows:
  - DirectSound [backend][BACKENDS]
  - Uses the Windows default recording and playback audio devices
  - 32-bit float sample type
- - 20 ms "preferred" buffer size
+ - 40 ms "preferred" buffer size
 
 All of the above can be customized using a [configuration file][CONFIGURATION].
 

src/FlexASIO/flexasio.cpp

@@ -357,7 +357,7 @@ namespace flexasio {
 			Log() << "Calculating default buffer size based on " << sampleRate << " Hz sample rate";
 			*minSize = long(sampleRate * 0.001); // 1 ms, there's basically no chance we'll get glitch-free streaming below this
 			*maxSize = long(sampleRate); // 1 second, more would be silly
-			*preferredSize = long(sampleRate * 0.02); // typical - 20 ms
+			*preferredSize = long(sampleRate * 0.04); // 40 ms - see https://github.com/dechamps/FlexASIO/issues/29
 			*granularity = 1; // Don't care
 		}
 		Log() << "Returning: min buffer size " << *minSize << ", max buffer size " << *maxSize << ", preferred buffer size " << *preferredSize << ", granularity " << *granularity;