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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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