Improves CoreAudioUtil::IsSupported by also loading Audioses.dll DLL

media/audio/win/core_audio_util_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/win/core_audio_util_win.h"
 
 #include <Audioclient.h>
 #include <Functiondiscoverykeys_devpkey.h>
 
 #include "base/command_line.h"
@@ skipping 48 matching lines @@
       return CHANNEL_LAYOUT_7_1_WIDE;
     case KSAUDIO_SPEAKER_7POINT1_SURROUND:
       DVLOG(2) << "KSAUDIO_SPEAKER_7POINT1_SURROUND=>CHANNEL_LAYOUT_7_1";
       return CHANNEL_LAYOUT_7_1;
     default:
       DVLOG(2) << "Unsupported channel layout: " << config;
       return CHANNEL_LAYOUT_UNSUPPORTED;
   }
 }
 
+bool LoadAudiosesDll() {
+  static const wchar_t* const kAudiosesDLL =
+      L"%WINDIR%\\system32\\audioses.dll";
+
+  wchar_t path[MAX_PATH] = {0};
+  ExpandEnvironmentStringsW(kAudiosesDLL, path, arraysize(path));
+  if (!LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH))

[tommi (sloooow) - chröme, 2012/12/21 09:58:14]

return LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH)) != NULL;

[henrika (OOO until Aug 14), 2012/12/21 10:03:36]

OK. I followed your example BTW ;-)

[tommi (sloooow) - chröme, 2012/12/21 10:29:18]

Hah, well, you should have noticed that in the other case there was a loop! :)
Think about how this would have worked:

  for (int i = 0; i < arraysize(kMfDLLs); ++i) {
    wchar_t path[MAX_PATH] = {0};
    ExpandEnvironmentStringsW(kMfDLLs[i], path, arraysize(path));
    return LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH)) != NULL;
  }

+    return false;
+
+  return true;
+}
+
 // Scoped PROPVARIANT class for automatically freeing a COM PROPVARIANT
 // structure at the end of a scope.
 class ScopedPropertyVariant {
  public:
   ScopedPropertyVariant() {
     PropVariantInit(&propvar_);
   }
   ~ScopedPropertyVariant() {
     PropVariantClear(&propvar_);
   }
@@ skipping 17 matching lines @@
  private:
   PROPVARIANT propvar_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedPropertyVariant);
 };
 
 bool CoreAudioUtil::IsSupported() {
   // Microsoft does not plan to make the Core Audio APIs available for use
   // with earlier versions of Windows, including Microsoft Windows Server 2003,
   // Windows XP, Windows Millennium Edition, Windows 2000, and Windows 98.
-  return (base::win::GetVersion() >= base::win::VERSION_VISTA);
+  if (base::win::GetVersion() < base::win::VERSION_VISTA)
+    return false;
+
+  // The audio core APIs are implemented in the Mmdevapi.dll and Audioses.dll
+  // system components, both of which run in user mode.

[tommi (sloooow) - chröme, 2012/12/21 09:58:14]

nit: dll's generally do run in usermode so you can remove that bit :)

[henrika (OOO until Aug 14), 2012/12/21 10:03:36]

Got it. Copy paste from MSDN.

+  // Dependcy Walker shows that it is enough to verify possibility to load

[tommi (sloooow) - chröme, 2012/12/21 09:58:14]

Dependency

[henrika (OOO until Aug 14), 2012/12/21 10:03:36]

Done.

+  // the Audioses DLL since it loads Mmdevapi.dll as well.

[tommi (sloooow) - chröme, 2012/12/21 09:58:14]

s/it loads Mmdevapi.dll as well/it depends on Mmdevapi.dll.
The loader loads the dlls, they don't do it themselves.

[henrika (OOO until Aug 14), 2012/12/21 10:03:36]

Thanks. Much better.

+  // See http://crbug.com/166397 why this extra step is required to guarantee
+  // Core Audio support.
+  static bool g_audioses_dll_available = LoadAudiosesDll();
+  return g_audioses_dll_available;
 }
 
 base::TimeDelta CoreAudioUtil::RefererenceTimeToTimeDelta(REFERENCE_TIME time) {
   // Each unit of reference time is 100 nanoseconds <=> 0.1 microsecond.
   return base::TimeDelta::FromMicroseconds(0.1 * time + 0.5);
 }
 
 AUDCLNT_SHAREMODE CoreAudioUtil::GetShareMode() {
   const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
   if (cmd_line->HasSwitch(switches::kEnableExclusiveAudio))
@@ skipping 454 matching lines @@
   HRESULT hr = client->GetService(__uuidof(IAudioCaptureClient),
                                   audio_capture_client.ReceiveVoid());
   if (FAILED(hr)) {
     DVLOG(1) << "IAudioClient::GetService: " << std::hex << hr;
     return ScopedComPtr<IAudioCaptureClient>();
   }
   return audio_capture_client;
 }
 
 }  // namespace media