Avoids irregular OnMoreData callbacks on Windows using Core Audio

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 531 matching lines @@
 
   // Get access to the IAudioRenderClient interface. This interface
   // enables us to write output data to a rendering endpoint buffer.
   ScopedComPtr<IAudioRenderClient> audio_render_client;
   HRESULT hr = client->GetService(__uuidof(IAudioRenderClient),
                                   audio_render_client.ReceiveVoid());
   if (FAILED(hr)) {
     DVLOG(1) << "IAudioClient::GetService: " << std::hex << hr;
     return ScopedComPtr<IAudioRenderClient>();
   }
-
-  // TODO(henrika): verify that this scheme is the same for shared mode and
-  // exclusive mode streams.
-
-  // Avoid start-up glitches by filling up the endpoint buffer with "silence"
-  // before starting the stream.
-  UINT32 endpoint_buffer_size = 0;
-  hr = client->GetBufferSize(&endpoint_buffer_size);
-  DVLOG_IF(1, FAILED(hr)) << "IAudioClient::GetBufferSize: " << std::hex << hr;
-
-  BYTE* data = NULL;
-  hr = audio_render_client->GetBuffer(endpoint_buffer_size, &data);
-  DVLOG_IF(1, FAILED(hr)) << "IAudioRenderClient::GetBuffer: "
-                          << std::hex << hr;
-  if (SUCCEEDED(hr)) {
-    // Using the AUDCLNT_BUFFERFLAGS_SILENT flag eliminates the need to
-    // explicitly write silence data to the rendering buffer.
-    hr = audio_render_client->ReleaseBuffer(endpoint_buffer_size,
-                                            AUDCLNT_BUFFERFLAGS_SILENT);
-    DVLOG_IF(1, FAILED(hr)) << "IAudioRenderClient::ReleaseBuffer: "
-                            << std::hex << hr;
-  }
-
-  // Sanity check: verify that the endpoint buffer is filled with silence.
-  UINT32 num_queued_frames = 0;
-  client->GetCurrentPadding(&num_queued_frames);
-  DCHECK(num_queued_frames == endpoint_buffer_size);
-
   return audio_render_client;
 }
 
 ScopedComPtr<IAudioCaptureClient> CoreAudioUtil::CreateCaptureClient(
     IAudioClient* client) {
   DCHECK(CoreAudioUtil::IsSupported());
 
   // Get access to the IAudioCaptureClient interface. This interface
   // enables us to read input data from a capturing endpoint buffer.
   ScopedComPtr<IAudioCaptureClient> audio_capture_client;
   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