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| 1 // Copyright (c) 2014 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2014 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 #ifndef MEDIA_BASE_AUDIO_SHIFTER_H | 5 #ifndef MEDIA_BASE_AUDIO_SHIFTER_H |
| 6 #define MEDIA_BASE_AUDIO_SHIFTER_H | 6 #define MEDIA_BASE_AUDIO_SHIFTER_H |
| 7 | 7 |
| 8 #include <stddef.h> | 8 #include <stddef.h> |
| 9 | 9 |
| 10 #include <deque> | 10 #include <deque> |
| 11 #include <memory> |
| 11 | 12 |
| 12 #include "base/memory/linked_ptr.h" | 13 #include "base/memory/linked_ptr.h" |
| 13 #include "base/memory/scoped_ptr.h" | |
| 14 #include "base/time/time.h" | 14 #include "base/time/time.h" |
| 15 #include "media/base/media_export.h" | 15 #include "media/base/media_export.h" |
| 16 #include "media/base/multi_channel_resampler.h" | 16 #include "media/base/multi_channel_resampler.h" |
| 17 | 17 |
| 18 namespace media { | 18 namespace media { |
| 19 | 19 |
| 20 class AudioBus; | 20 class AudioBus; |
| 21 class ClockSmoother; | 21 class ClockSmoother; |
| 22 | 22 |
| 23 // This class works like a buffer between a push based audio source | 23 // This class works like a buffer between a push based audio source |
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| 67 // channels, but bus size can vary. The playout time can be noisy and | 67 // channels, but bus size can vary. The playout time can be noisy and |
| 68 // does not have to line up perfectly with the number of samples pushed | 68 // does not have to line up perfectly with the number of samples pushed |
| 69 // so far. However, the playout_time in Push calls and Pull calls must | 69 // so far. However, the playout_time in Push calls and Pull calls must |
| 70 // not diverge over time. | 70 // not diverge over time. |
| 71 // Given audio from an a microphone, a reasonable way to calculate | 71 // Given audio from an a microphone, a reasonable way to calculate |
| 72 // playout_time would be now + 30ms. | 72 // playout_time would be now + 30ms. |
| 73 // Ideally playout_time is some time in the future, in which case | 73 // Ideally playout_time is some time in the future, in which case |
| 74 // the samples will be buffered until the approperiate time. If | 74 // the samples will be buffered until the approperiate time. If |
| 75 // playout_time is in the past, everything will still work, and we'll | 75 // playout_time is in the past, everything will still work, and we'll |
| 76 // try to keep the buffring to a minimum. | 76 // try to keep the buffring to a minimum. |
| 77 void Push(scoped_ptr<AudioBus> input, base::TimeTicks playout_time); | 77 void Push(std::unique_ptr<AudioBus> input, base::TimeTicks playout_time); |
| 78 | 78 |
| 79 // Fills out |output| with samples. Tries to stretch/shrink the audio | 79 // Fills out |output| with samples. Tries to stretch/shrink the audio |
| 80 // to compensate for drift between input and output. | 80 // to compensate for drift between input and output. |
| 81 // If called from an output device data pull, a reasonable way to | 81 // If called from an output device data pull, a reasonable way to |
| 82 // calculate playout_time would be now + audio pipeline delay. | 82 // calculate playout_time would be now + audio pipeline delay. |
| 83 void Pull(AudioBus* output, base::TimeTicks playout_time); | 83 void Pull(AudioBus* output, base::TimeTicks playout_time); |
| 84 | 84 |
| 85 private: | 85 private: |
| 86 void Zero(AudioBus* output); | 86 void Zero(AudioBus* output); |
| 87 void ResamplerCallback(int frame_delay, AudioBus* destination); | 87 void ResamplerCallback(int frame_delay, AudioBus* destination); |
| 88 | 88 |
| 89 struct AudioQueueEntry { | 89 struct AudioQueueEntry { |
| 90 AudioQueueEntry(base::TimeTicks target_playout_time_, | 90 AudioQueueEntry(base::TimeTicks target_playout_time_, |
| 91 scoped_ptr<AudioBus> audio_); | 91 std::unique_ptr<AudioBus> audio_); |
| 92 AudioQueueEntry(const AudioQueueEntry& other); | 92 AudioQueueEntry(const AudioQueueEntry& other); |
| 93 ~AudioQueueEntry(); | 93 ~AudioQueueEntry(); |
| 94 base::TimeTicks target_playout_time; | 94 base::TimeTicks target_playout_time; |
| 95 linked_ptr<AudioBus> audio; | 95 linked_ptr<AudioBus> audio; |
| 96 }; | 96 }; |
| 97 | 97 |
| 98 typedef std::deque<AudioQueueEntry> AudioShifterQueue; | 98 typedef std::deque<AudioQueueEntry> AudioShifterQueue; |
| 99 | 99 |
| 100 // Set from constructor. | 100 // Set from constructor. |
| 101 const base::TimeDelta max_buffer_size_; | 101 const base::TimeDelta max_buffer_size_; |
| 102 const base::TimeDelta clock_accuracy_; | 102 const base::TimeDelta clock_accuracy_; |
| 103 const base::TimeDelta adjustment_time_; | 103 const base::TimeDelta adjustment_time_; |
| 104 const int rate_; | 104 const int rate_; |
| 105 const int channels_; | 105 const int channels_; |
| 106 | 106 |
| 107 // The clock smoothers are used to smooth out timestamps | 107 // The clock smoothers are used to smooth out timestamps |
| 108 // and adjust for drift and inaccurate clocks. | 108 // and adjust for drift and inaccurate clocks. |
| 109 scoped_ptr<ClockSmoother> input_clock_smoother_; | 109 std::unique_ptr<ClockSmoother> input_clock_smoother_; |
| 110 scoped_ptr<ClockSmoother> output_clock_smoother_; | 110 std::unique_ptr<ClockSmoother> output_clock_smoother_; |
| 111 | 111 |
| 112 // Are we currently outputting data? | 112 // Are we currently outputting data? |
| 113 bool running_; | 113 bool running_; |
| 114 | 114 |
| 115 // Number of frames already consumed from |queue_|. | 115 // Number of frames already consumed from |queue_|. |
| 116 size_t position_; | 116 size_t position_; |
| 117 | 117 |
| 118 // Queue of data provided to us. | 118 // Queue of data provided to us. |
| 119 AudioShifterQueue queue_; | 119 AudioShifterQueue queue_; |
| 120 | 120 |
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| 134 // Resampler. | 134 // Resampler. |
| 135 MultiChannelResampler resampler_; | 135 MultiChannelResampler resampler_; |
| 136 | 136 |
| 137 // Current resampler ratio. | 137 // Current resampler ratio. |
| 138 double current_ratio_; | 138 double current_ratio_; |
| 139 }; | 139 }; |
| 140 | 140 |
| 141 } // namespace media | 141 } // namespace media |
| 142 | 142 |
| 143 #endif // MEDIA_BASE_AUDIO_SHIFTER_H | 143 #endif // MEDIA_BASE_AUDIO_SHIFTER_H |
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