1// Copyright 2014 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
5#ifndef MEDIA_BASE_AUDIO_BUFFER_CONVERTER
6#define MEDIA_BASE_AUDIO_BUFFER_CONVERTER
7
8#include <deque>
9
10#include "base/memory/ref_counted.h"
11#include "base/memory/scoped_ptr.h"
12#include "base/time/time.h"
13#include "media/audio/audio_parameters.h"
14#include "media/base/audio_converter.h"
15#include "media/base/audio_timestamp_helper.h"
16#include "media/base/media_export.h"
17
18namespace media {
19
20class AudioBuffer;
21class AudioBus;
22
23// Takes AudioBuffers in any format and uses an AudioConverter to convert them
24// to a common format (usually the hardware output format).
25class MEDIA_EXPORT AudioBufferConverter : public AudioConverter::InputCallback {
26 public:
27  explicit AudioBufferConverter(const AudioParameters& output_params);
28  virtual ~AudioBufferConverter();
29
30  void AddInput(const scoped_refptr<AudioBuffer>& buffer);
31
32  // Is an output buffer available via GetNextBuffer()?
33  bool HasNextBuffer();
34
35  // This should only be called this is HasNextBuffer() returns true.
36  scoped_refptr<AudioBuffer> GetNextBuffer();
37
38  // Reset internal state.
39  void Reset();
40
41  // Reset internal timestamp state. Upon the next AddInput() call, our base
42  // timestamp will be set to match the input buffer.
43  void ResetTimestampState();
44
45  int input_buffer_size_for_testing() const {
46    return input_params_.frames_per_buffer();
47  }
48  int input_frames_left_for_testing() const {
49    return input_frames_;
50  }
51
52 private:
53  // Callback to provide data to the AudioConverter
54  virtual double ProvideInput(AudioBus* audio_bus,
55                              base::TimeDelta buffer_delay) OVERRIDE;
56
57  // Reset the converter in response to a configuration change.
58  void ResetConverter(const scoped_refptr<AudioBuffer>& input_buffer);
59
60  // Perform conversion if we have enough data.
61  void ConvertIfPossible();
62
63  // Flush remaining output
64  void Flush();
65
66  // The output parameters.
67  AudioParameters output_params_;
68
69  // The current input parameters (we cache these to detect configuration
70  // changes, so we know when to reset the AudioConverter).
71  AudioParameters input_params_;
72
73  typedef std::deque<scoped_refptr<AudioBuffer> > BufferQueue;
74
75  // Queued up inputs (there will never be all that much data stored here, as
76  // soon as there's enough here to produce an output buffer we will do so).
77  BufferQueue queued_inputs_;
78
79  // Offset into the front element of |queued_inputs_|. A ProvideInput() call
80  // doesn't necessarily always consume an entire buffer.
81  int last_input_buffer_offset_;
82
83  // Buffer of output frames, to be returned by GetNextBuffer().
84  BufferQueue queued_outputs_;
85
86  // How many frames of input we have in |queued_inputs_|.
87  int input_frames_;
88
89  // Input frames in the AudioConverter's internal buffers.
90  double buffered_input_frames_;
91
92  // Ratio of sample rates, in/out.
93  double io_sample_rate_ratio_;
94
95  // Computes timestamps in terms of the output sample rate.
96  AudioTimestampHelper timestamp_helper_;
97
98  // Are we flushing everything, without regard for providing AudioConverter
99  // full AudioBuses in ProvideInput()?
100  bool is_flushing_;
101
102  // The AudioConverter which does the real work here.
103  scoped_ptr<AudioConverter> audio_converter_;
104};
105
106}  // namespace media
107
108#endif  // MEDIA_BASE_AUDIO_BUFFER_CONVERTER
109