Adds SpeechRecognizer which provides a simple interface to record and recognize speech.

chrome/browser/speech/speech_recognizer.cc

+// Copyright (c) 2010 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 "chrome/browser/speech/speech_recognizer.h"
+
+#include "base/ref_counted.h"
+#include "base/scoped_ptr.h"
+#include "chrome/browser/chrome_thread.h"
+#include "chrome/browser/profile.h"
+#include "chrome/common/net/url_request_context_getter.h"
+
+using media::AudioInputController;
+using std::list;
+using std::string;
+
+namespace {
+const char* kDefaultSpeechRecognitionUrl =
+    "http://www.google.com/speech-api/v1/recognize?lang=en-us&client=chromium";
+const int kAudioPacketIntervalMs = 100;  // Record 100ms long audio packets.
+const int kNumAudioChannels = 1;  // Speech is recorded as mono.
+const int kNumBitsPerAudioSample = 16;
+}  // namespace
+
+namespace speech_input {
+
+SpeechRecognizer::SpeechRecognizer(Delegate* delegate, int render_view_id)
+    : delegate_(delegate),
+      render_view_id_(render_view_id) {
+}
+
+SpeechRecognizer::~SpeechRecognizer() {
+  // Recording should have stopped earlier due to the endpointer or
+  // |StopRecording| being called.
+  DCHECK(!audio_controller_.get());
+  DCHECK(!request_.get() || !request_->HasPendingRequest());
+  DCHECK(audio_buffers_.empty());
+}
+
+bool SpeechRecognizer::StartRecording() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
+  DCHECK(!audio_controller_.get());
+  DCHECK(!request_.get() || !request_->HasPendingRequest());
+
+  audio_controller_ = AudioInputController::Create(this,
+      AudioManager::AUDIO_PCM_LINEAR, kNumAudioChannels,
+      AudioManager::kTelephoneSampleRate, kNumBitsPerAudioSample,
+      (AudioManager::kTelephoneSampleRate * kAudioPacketIntervalMs) / 1000);
+  DCHECK(audio_controller_.get());
+  LOG(INFO) << "SpeechRecognizer starting record.";
+  audio_controller_->Record();
+
+  return true;
+}
+
+void SpeechRecognizer::CancelRecognition() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
+  DCHECK(audio_controller_.get() || request_.get());
+
+  // Stop recording if required.
+  if (audio_controller_.get()) {
+    LOG(INFO) << "SpeechRecognizer stopping record.";
+    audio_controller_->Close();
+    audio_controller_ = NULL;  // Releases the ref ptr.
+  }
+
+  LOG(INFO) << "SpeechRecognizer canceling recognition.";
+  ReleaseAudioBuffers();
+  request_.reset();
+}
+
+void SpeechRecognizer::StopRecording() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
+
+  // If audio recording has already stopped and we are in recognition phase,
+  // silently ignore any more calls to stop recording.
+  if (!audio_controller_.get())
+    return;
+
+  LOG(INFO) << "SpeechRecognizer stopping record.";
+  audio_controller_->Close();
+  audio_controller_ = NULL;  // Releases the ref ptr.
+  delegate_->DidCompleteRecording(render_view_id_);
+
+  // If we haven't got any audio yet end the recognition sequence here.
+  if (audio_buffers_.empty()) {
+    // Guard against the delegate freeing us until we finish our job.
+    scoped_refptr<SpeechRecognizer> me(this);
+    delegate_->DidCompleteRecognition(render_view_id_);
+    return;
+  }
+
+  // We now have recorded audio in our buffers, so start a recognition request.
+  // Since the http request takes a single string as POST data, allocate
+  // one and copy over bytes from the audio buffers to the string.
+  int audio_buffer_length = 0;
+  for (AudioBufferQueue::iterator it = audio_buffers_.begin();
+       it != audio_buffers_.end(); it++) {
+    audio_buffer_length += (*it)->length();
+  }
+  string data;
+  data.reserve(audio_buffer_length);
+  for (AudioBufferQueue::iterator it = audio_buffers_.begin();
+       it != audio_buffers_.end(); it++) {
+    data.append(*(*it));
+  }
+  DCHECK(!request_.get());
+  request_.reset(new SpeechRecognitionRequest(
+      Profile::GetDefaultRequestContext(),
+      GURL(kDefaultSpeechRecognitionUrl),
+      this));
+  request_->Send(data);
+  ReleaseAudioBuffers();  // No need to keep the audio anymore.
+}
+
+void SpeechRecognizer::ReleaseAudioBuffers() {
+  for (AudioBufferQueue::iterator it = audio_buffers_.begin();
+       it != audio_buffers_.end(); it++)
+    delete *it;
+  audio_buffers_.clear();
+}
+
+// Invoked in the audio thread.
+void SpeechRecognizer::OnError(AudioInputController* controller,
+                               int error_code) {
+  ChromeThread::PostTask(ChromeThread::IO, FROM_HERE,
+                         NewRunnableMethod(this,
+                                           &SpeechRecognizer::HandleOnError,
+                                           error_code));
+}
+
+void SpeechRecognizer::HandleOnError(int error_code) {
+  LOG(WARNING) << "SpeechRecognizer::HandleOnError, code=" << error_code;
+
+  // Check if we are still recording before canceling recognition, as
+  // recording might have been stopped after this error was posted to the queue
+  // by |OnError|.
+  if (!audio_controller_.get())
+    return;
+
+  CancelRecognition();
+  delegate_->DidCompleteRecording(render_view_id_);
+  delegate_->DidCompleteRecognition(render_view_id_);
+}
+
+void SpeechRecognizer::OnData(AudioInputController* controller,
+                              const uint8* data, uint32 size) {
+  if (size == 0)  // This could happen when recording stops and is normal.
+    return;
+
+  string* str_data = new string(reinterpret_cast<const char*>(data), size);
+  ChromeThread::PostTask(ChromeThread::IO, FROM_HERE,
+                         NewRunnableMethod(this,
+                                           &SpeechRecognizer::HandleOnData,
+                                           str_data));
+}
+
+void SpeechRecognizer::HandleOnData(string* data) {
+  // Check if we are still recording and if not discard this buffer, as
+  // recording might have been stopped after this buffer was posted to the queue
+  // by |OnData|.
+  if (!audio_controller_.get()) {
+    delete data;
+    return;
+  }
+
+  // TODO(satish): Once we have streaming POST, start sending the data received
+  // here as POST chunks.
+  audio_buffers_.push_back(data);
+}
+
+void SpeechRecognizer::SetRecognitionResult(bool error, const string16& value) {
+  delegate_->SetRecognitionResult(render_view_id_, error, value);
+
+  // Guard against the delegate freeing us until we finish our job.
+  scoped_refptr<SpeechRecognizer> me(this);
+  delegate_->DidCompleteRecognition(render_view_id_);
+}
+
+}  // namespace speech_input