Added support for multiple sampling rates on Windows.

Review URL: https://chromiumcodereview.appspot.com/10818010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148766 0039d316-1c4b-4281-b951-d872f2087c98

remoting/host/audio_capturer.cc

@@ -0,0 +1,21 @@
+// 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 "remoting/host/audio_capturer.h"
+
+#include "remoting/proto/audio.pb.h"
+
+namespace remoting {
+
+bool AudioCapturer::IsValidSampleRate(int sample_rate) {
+  switch (sample_rate) {
+    case AudioPacket::SAMPLING_RATE_44100:
+    case AudioPacket::SAMPLING_RATE_48000:
+      return true;
+    default:
+      return false;
+  }
+}
+
+} // namespace remoting

remoting/host/audio_capturer.h

@@ -7,10 +7,11 @@
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
-#include "remoting/proto/audio.pb.h"
 
 namespace remoting {
 
+class AudioPacket;
+
 class AudioCapturer {
  public:
   typedef base::Callback<void(scoped_ptr<AudioPacket> packet)>
@@ -20,15 +21,17 @@ class AudioCapturer {
 
   static scoped_ptr<AudioCapturer> Create();
 
-  // Capturers should sample at a 44.1 kHz sampling rate, in uncompressed PCM
-  // stereo format. Capturers may choose the number of frames per packet.
+  // Capturers should sample at a 44.1 or 48 kHz sampling rate, in uncompressed
+  // PCM stereo format. Capturers may choose the number of frames per packet.
   // Returns true on success.
   virtual bool Start(const PacketCapturedCallback& callback) = 0;
   // Stops the audio capturer, and frees the OS-specific audio capture
   // resources.
   virtual void Stop() = 0;
   // Returns true if the audio capturer is running.
   virtual bool IsRunning() = 0;
+
+  static bool IsValidSampleRate(int sample_rate);
 };
 
 }  // namespace remoting

remoting/host/audio_capturer_win.cc

@@ -23,7 +23,6 @@
 namespace {
 const int kChannels = 2;
 const int kBitsPerSample = 16;
-const int kSamplesPerSecond = 44100;
 const int kBitsPerByte = 8;
 // Conversion factor from 100ns to 1ms.
 const int kHnsToMs = 10000;
@@ -48,6 +47,8 @@ class AudioCapturerWin : public AudioCapturer {
 
   PacketCapturedCallback callback_;
 
+  AudioPacket::SamplingRate sampling_rate_;
+
   scoped_ptr<base::RepeatingTimer<AudioCapturerWin> > capture_timer_;
   base::TimeDelta audio_device_period_;
 
@@ -62,8 +63,9 @@ class AudioCapturerWin : public AudioCapturer {
   DISALLOW_COPY_AND_ASSIGN(AudioCapturerWin);
 };
 
-AudioCapturerWin::AudioCapturerWin() {
-  thread_checker_.DetachFromThread();
+AudioCapturerWin::AudioCapturerWin()
+    : sampling_rate_(AudioPacket::SAMPLING_RATE_INVALID) {
+      thread_checker_.DetachFromThread();
 }
 
 AudioCapturerWin::~AudioCapturerWin() {
@@ -131,38 +133,52 @@ bool AudioCapturerWin::Start(const PacketCapturedCallback& callback) {
     case WAVE_FORMAT_IEEE_FLOAT:
       // Intentional fall-through.
     case WAVE_FORMAT_PCM:
+      if (!AudioCapturer::IsValidSampleRate(wave_format_ex_->nSamplesPerSec)) {
+        LOG(ERROR) << "Host sampling rate is neither 44.1 kHz nor 48 kHz.";
+        return false;
+      }
+      sampling_rate_ = static_cast<AudioPacket::SamplingRate>(
+          wave_format_ex_->nSamplesPerSec);
+
       wave_format_ex_->wFormatTag = WAVE_FORMAT_PCM;
       wave_format_ex_->nChannels = kChannels;
-      wave_format_ex_->nSamplesPerSec = kSamplesPerSecond;
       wave_format_ex_->wBitsPerSample = kBitsPerSample;
       wave_format_ex_->nBlockAlign = kChannels * kBitsPerSample / kBitsPerByte;
       wave_format_ex_->nAvgBytesPerSec =
-          kSamplesPerSecond * kChannels * kBitsPerSample / kBitsPerByte;
+          sampling_rate_ * kChannels * kBitsPerSample / kBitsPerByte;
       break;
     case WAVE_FORMAT_EXTENSIBLE: {
       PWAVEFORMATEXTENSIBLE wave_format_extensible =
           reinterpret_cast<WAVEFORMATEXTENSIBLE*>(
           static_cast<WAVEFORMATEX*>(wave_format_ex_));
       if (IsEqualGUID(KSDATAFORMAT_SUBTYPE_IEEE_FLOAT,
                       wave_format_extensible->SubFormat)) {
+        if (!AudioCapturer::IsValidSampleRate(
+                wave_format_extensible->Format.nSamplesPerSec)) {
+          LOG(ERROR) << "Host sampling rate is neither 44.1 kHz nor 48 kHz.";
+          return false;
+        }
+        sampling_rate_ = static_cast<AudioPacket::SamplingRate>(
+            wave_format_extensible->Format.nSamplesPerSec);
+
         wave_format_extensible->SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
         wave_format_extensible->Samples.wValidBitsPerSample = kBitsPerSample;
 
         wave_format_extensible->Format.nChannels = kChannels;
-        wave_format_extensible->Format.nSamplesPerSec = kSamplesPerSecond;
+        wave_format_extensible->Format.nSamplesPerSec = sampling_rate_;
         wave_format_extensible->Format.wBitsPerSample = kBitsPerSample;
         wave_format_extensible->Format.nBlockAlign =
             kChannels * kBitsPerSample / kBitsPerByte;
         wave_format_extensible->Format.nAvgBytesPerSec =
-            kSamplesPerSecond * kChannels * kBitsPerSample / kBitsPerByte;
+            sampling_rate_ * kChannels * kBitsPerSample / kBitsPerByte;
       } else {
         LOG(ERROR) << "Failed to force 16-bit samples";
         return false;
       }
       break;
     }
     default:
-      LOG(ERROR) << "Failed to force 16-bit samples";
+      LOG(ERROR) << "Failed to force 16-bit PCM";
       return false;
   }
 
@@ -221,6 +237,7 @@ bool AudioCapturerWin::IsRunning() {
 }
 
 void AudioCapturerWin::DoCapture() {
+  DCHECK(AudioCapturer::IsValidSampleRate(sampling_rate_));
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(IsRunning());
 
@@ -249,6 +266,7 @@ void AudioCapturerWin::DoCapture() {
 
     scoped_ptr<AudioPacket> packet = scoped_ptr<AudioPacket>(new AudioPacket());
     packet->set_data(data, frames * wave_format_ex_->nBlockAlign);
+    packet->set_sampling_rate(sampling_rate_);
 
     callback_.Run(packet.Pass());
 

remoting/remoting.gyp

@@ -1130,6 +1130,7 @@
         '../crypto/crypto.gyp:crypto',
       ],
       'sources': [
+        'host/audio_capturer.cc',
         'host/audio_capturer.h',
         'host/audio_capturer_linux.cc',
         'host/audio_capturer_mac.cc',