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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // Implementation of AudioOutputStream for Windows using Windows Core Audio | 5 // Implementation of AudioOutputStream for Windows using Windows Core Audio |
6 // WASAPI for low latency rendering. | 6 // WASAPI for low latency rendering. |
7 // | 7 // |
8 // Overview of operation and performance: | 8 // Overview of operation and performance: |
9 // | 9 // |
10 // - An object of WASAPIAudioOutputStream is created by the AudioManager | 10 // - An object of WASAPIAudioOutputStream is created by the AudioManager |
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232 // data to a rendering endpoint buffer. | 232 // data to a rendering endpoint buffer. |
233 base::win::ScopedComPtr<IAudioRenderClient> audio_render_client_; | 233 base::win::ScopedComPtr<IAudioRenderClient> audio_render_client_; |
234 | 234 |
235 // The audio engine will signal this event each time a buffer becomes | 235 // The audio engine will signal this event each time a buffer becomes |
236 // ready to be filled by the client. | 236 // ready to be filled by the client. |
237 base::win::ScopedHandle audio_samples_render_event_; | 237 base::win::ScopedHandle audio_samples_render_event_; |
238 | 238 |
239 // This event will be signaled when rendering shall stop. | 239 // This event will be signaled when rendering shall stop. |
240 base::win::ScopedHandle stop_render_event_; | 240 base::win::ScopedHandle stop_render_event_; |
241 | 241 |
| 242 // A ratio used to convert 100-nanosecond 'pu64QPCPosition' time units |
| 243 // (obtained from IAudioClock::GetPosition()) to raw performance counter |
| 244 // time units. |
| 245 double hns_units_to_perf_count_; |
| 246 |
242 // Container for retrieving data from AudioSourceCallback::OnMoreData(). | 247 // Container for retrieving data from AudioSourceCallback::OnMoreData(). |
243 std::unique_ptr<AudioBus> audio_bus_; | 248 std::unique_ptr<AudioBus> audio_bus_; |
244 | 249 |
245 base::win::ScopedComPtr<IAudioClock> audio_clock_; | 250 base::win::ScopedComPtr<IAudioClock> audio_clock_; |
246 | 251 |
247 DISALLOW_COPY_AND_ASSIGN(WASAPIAudioOutputStream); | 252 DISALLOW_COPY_AND_ASSIGN(WASAPIAudioOutputStream); |
248 }; | 253 }; |
249 | 254 |
250 } // namespace media | 255 } // namespace media |
251 | 256 |
252 #endif // MEDIA_AUDIO_WIN_AUDIO_LOW_LATENCY_OUTPUT_WIN_H_ | 257 #endif // MEDIA_AUDIO_WIN_AUDIO_LOW_LATENCY_OUTPUT_WIN_H_ |
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