audio_push_fifo.cc 2.8 KB

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  1. // Copyright 2016 The Chromium Authors. All rights reserved.
  2. // Use of this source code is governed by a BSD-style license that can be
  3. // found in the LICENSE file.
  4. #include "media/base/audio_push_fifo.h"
  5. #include <algorithm>
  6. #include "base/logging.h"
  7. #include "base/trace_event/trace_event.h"
  8. namespace media {
  9. AudioPushFifo::AudioPushFifo(const OutputCallback& callback)
  10. : callback_(callback), frames_per_buffer_(0) {
  11. DCHECK(!callback_.is_null());
  12. }
  13. AudioPushFifo::~AudioPushFifo() = default;
  14. void AudioPushFifo::Reset(int frames_per_buffer) {
  15. DCHECK_GT(frames_per_buffer, 0);
  16. audio_queue_.reset();
  17. queued_frames_ = 0;
  18. frames_per_buffer_ = frames_per_buffer;
  19. }
  20. void AudioPushFifo::Push(const AudioBus& input_bus) {
  21. TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("audio"), "AudioPushFifo::Push");
  22. DCHECK_GT(frames_per_buffer_, 0);
  23. // Fast path: No buffering required.
  24. if ((queued_frames_ == 0) && (input_bus.frames() == frames_per_buffer_)) {
  25. callback_.Run(input_bus, 0);
  26. return;
  27. }
  28. // Lazy-create the |audio_queue_| if needed.
  29. if (!audio_queue_ || audio_queue_->channels() != input_bus.channels())
  30. audio_queue_ = AudioBus::Create(input_bus.channels(), frames_per_buffer_);
  31. // Start with a frame offset that refers to the position of the first sample
  32. // in |audio_queue_| relative to the first sample in |input_bus|.
  33. int frame_delay = -queued_frames_;
  34. // Repeatedly fill up |audio_queue_| with more sample frames from |input_bus|
  35. // and deliver batches until all sample frames in |input_bus| have been
  36. // consumed.
  37. int input_offset = 0;
  38. do {
  39. // Attempt to fill |audio_queue_| completely.
  40. const int frames_to_enqueue =
  41. std::min(static_cast<int>(input_bus.frames() - input_offset),
  42. frames_per_buffer_ - queued_frames_);
  43. if (frames_to_enqueue > 0) {
  44. DVLOG(2) << "Enqueuing " << frames_to_enqueue << " frames.";
  45. input_bus.CopyPartialFramesTo(input_offset, frames_to_enqueue,
  46. queued_frames_, audio_queue_.get());
  47. queued_frames_ += frames_to_enqueue;
  48. input_offset += frames_to_enqueue;
  49. }
  50. // If |audio_queue_| has been filled completely, deliver the re-buffered
  51. // audio to the consumer.
  52. if (queued_frames_ == frames_per_buffer_) {
  53. DVLOG(2) << "Delivering another " << queued_frames_ << " frames.";
  54. callback_.Run(*audio_queue_, frame_delay);
  55. frame_delay += frames_per_buffer_;
  56. queued_frames_ = 0;
  57. } else {
  58. // Not enough frames queued-up yet to deliver more frames.
  59. }
  60. } while (input_offset < input_bus.frames());
  61. }
  62. void AudioPushFifo::Flush() {
  63. if (queued_frames_ == 0)
  64. return;
  65. audio_queue_->ZeroFramesPartial(queued_frames_,
  66. audio_queue_->frames() - queued_frames_);
  67. callback_.Run(*audio_queue_, -queued_frames_);
  68. queued_frames_ = 0;
  69. }
  70. } // namespace media