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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 #include "media/audio/win/audio_low_latency_output_win.h" | 5 #include "media/audio/win/audio_low_latency_output_win.h" |
| 6 | 6 |
| 7 #include <Functiondiscoverykeys_devpkey.h> | 7 #include <Functiondiscoverykeys_devpkey.h> |
| 8 | 8 |
| 9 #include "base/command_line.h" | 9 #include "base/command_line.h" |
| 10 #include "base/debug/trace_event.h" | 10 #include "base/debug/trace_event.h" |
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| 469 << std::hex << hr; | 469 << std::hex << hr; |
| 470 return false; | 470 return false; |
| 471 } | 471 } |
| 472 | 472 |
| 473 // Derive the audio delay which corresponds to the delay between | 473 // Derive the audio delay which corresponds to the delay between |
| 474 // a render event and the time when the first audio sample in a | 474 // a render event and the time when the first audio sample in a |
| 475 // packet is played out through the speaker. This delay value | 475 // packet is played out through the speaker. This delay value |
| 476 // can typically be utilized by an acoustic echo-control (AEC) | 476 // can typically be utilized by an acoustic echo-control (AEC) |
| 477 // unit at the render side. | 477 // unit at the render side. |
| 478 UINT64 position = 0; | 478 UINT64 position = 0; |
| 479 int audio_delay_bytes = 0; | 479 uint32 audio_delay_bytes = 0; |
| 480 hr = audio_clock_->GetPosition(&position, NULL); | 480 hr = audio_clock_->GetPosition(&position, NULL); |
| 481 if (SUCCEEDED(hr)) { | 481 if (SUCCEEDED(hr)) { |
| 482 // Stream position of the sample that is currently playing | 482 // Stream position of the sample that is currently playing |
| 483 // through the speaker. | 483 // through the speaker. |
| 484 double pos_sample_playing_frames = format_.Format.nSamplesPerSec * | 484 double pos_sample_playing_frames = format_.Format.nSamplesPerSec * |
| 485 (static_cast<double>(position) / device_frequency); | 485 (static_cast<double>(position) / device_frequency); |
| 486 | 486 |
| 487 // Stream position of the last sample written to the endpoint | 487 // Stream position of the last sample written to the endpoint |
| 488 // buffer. Note that, the packet we are about to receive in | 488 // buffer. Note that, the packet we are about to receive in |
| 489 // the upcoming callback is also included. | 489 // the upcoming callback is also included. |
| 490 size_t pos_last_sample_written_frames = | 490 size_t pos_last_sample_written_frames = |
| 491 num_written_frames_ + packet_size_frames_; | 491 num_written_frames_ + packet_size_frames_; |
| 492 | 492 |
| 493 // Derive the actual delay value which will be fed to the | 493 // Derive the actual delay value which will be fed to the |
| 494 // render client using the OnMoreData() callback. | 494 // render client using the OnMoreData() callback. |
| 495 audio_delay_bytes = (pos_last_sample_written_frames - | 495 audio_delay_bytes = (pos_last_sample_written_frames - |
| 496 pos_sample_playing_frames) * format_.Format.nBlockAlign; | 496 pos_sample_playing_frames) * format_.Format.nBlockAlign; |
| 497 } | 497 } |
| 498 | 498 |
| 499 // Read a data packet from the registered client source and | 499 // Read a data packet from the registered client source and |
| 500 // deliver a delay estimate in the same callback to the client. | 500 // deliver a delay estimate in the same callback to the client. |
| 501 // A time stamp is also stored in the AudioBuffersState. This | |
| 502 // time stamp can be used at the client side to compensate for | |
| 503 // the delay between the usage of the delay value and the time | |
| 504 // of generation. | |
| 505 | 501 |
| 506 int frames_filled = source_->OnMoreData( | 502 int frames_filled = source_->OnMoreData( |
| 507 audio_bus_.get(), AudioBuffersState(0, audio_delay_bytes)); | 503 audio_bus_.get(), audio_delay_bytes); |
| 508 uint32 num_filled_bytes = frames_filled * format_.Format.nBlockAlign; | 504 uint32 num_filled_bytes = frames_filled * format_.Format.nBlockAlign; |
| 509 DCHECK_LE(num_filled_bytes, packet_size_bytes_); | 505 DCHECK_LE(num_filled_bytes, packet_size_bytes_); |
| 510 | 506 |
| 511 // Note: If this ever changes to output raw float the data must be | 507 // Note: If this ever changes to output raw float the data must be |
| 512 // clipped and sanitized since it may come from an untrusted | 508 // clipped and sanitized since it may come from an untrusted |
| 513 // source such as NaCl. | 509 // source such as NaCl. |
| 514 const int bytes_per_sample = format_.Format.wBitsPerSample >> 3; | 510 const int bytes_per_sample = format_.Format.wBitsPerSample >> 3; |
| 515 audio_bus_->Scale(volume_); | 511 audio_bus_->Scale(volume_); |
| 516 audio_bus_->ToInterleaved( | 512 audio_bus_->ToInterleaved( |
| 517 frames_filled, bytes_per_sample, audio_data); | 513 frames_filled, bytes_per_sample, audio_data); |
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| 620 | 616 |
| 621 // Ensure that we don't quit the main thread loop immediately next | 617 // Ensure that we don't quit the main thread loop immediately next |
| 622 // time Start() is called. | 618 // time Start() is called. |
| 623 ResetEvent(stop_render_event_.Get()); | 619 ResetEvent(stop_render_event_.Get()); |
| 624 } | 620 } |
| 625 | 621 |
| 626 source_ = NULL; | 622 source_ = NULL; |
| 627 } | 623 } |
| 628 | 624 |
| 629 } // namespace media | 625 } // namespace media |
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