Use 2 buffers on presumable good Windows boxes.

media/audio/audio_util.cc

Index: media/audio/audio_util.cc
===================================================================
--- media/audio/audio_util.cc	(revision 140416)
+++ media/audio/audio_util.cc	(working copy)
@@ -21,6 +21,7 @@
 #include "base/shared_memory.h"
 #include "base/time.h"
 #if defined(OS_WIN)
+#include "base/sys_info.h"
 #include "base/win/windows_version.h"
 #include "media/audio/audio_manager_base.h"
 #endif
@@ -519,6 +520,17 @@
   return base::win::GetVersion() >= base::win::VERSION_VISTA;
 }
 
+int NumberOfWaveOutBuffers() {
+  // Simple heuristic: use 3 buffers on single-core system or on Vista,
+  // 3 otherwise.

[scherkus (not reviewing), 2012/06/07 17:25:41]

"use 3 buffers [...], 3 otherwise" ?

do you mean 2?

I'd also like to see a small explanation / URL link that explains why vista gets
stuck w/ 3 buffers and not XP nor Win7

[enal1, 2012/06/07 20:56:22]

Done.

+  int num_buffers = 2;
+  if ((base::SysInfo::NumberOfProcessors() < 2) ||
+      (base::win::GetVersion() == base::win::VERSION_VISTA)) {
+    num_buffers = 3;
+  }
+  return num_buffers;

[scherkus (not reviewing), 2012/06/07 17:25:41]

nit: how about dropping the num_buffers stuff and writing this as:

if (cpus < 2 || win == VISTA) {
  return 3;
}
return 2;

[enal1, 2012/06/07 20:56:22]

Done.

+}
+
 #endif
 
 }  // namespace media