audio_buffer.h revision 5c02ac1a9c1b504631c0a3d2b6e737b5d738bae1 
1// Copyright 2013 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_H_
6#define MEDIA_BASE_AUDIO_BUFFER_H_
7
8#include <vector>
9
10#include "base/memory/aligned_memory.h"
11#include "base/memory/ref_counted.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/time/time.h"
14#include "media/base/channel_layout.h"
15#include "media/base/media_export.h"
16#include "media/base/sample_format.h"
17
18namespace media {
19class AudioBus;
20
21// An audio buffer that takes a copy of the data passed to it, holds it, and
22// copies it into an AudioBus when needed. Also supports an end of stream
23// marker.
24class MEDIA_EXPORT AudioBuffer
25    : public base::RefCountedThreadSafe<AudioBuffer> {
26 public:
27  // Alignment of each channel's data; this must match what ffmpeg expects
28  // (which may be 0, 16, or 32, depending on the processor). Selecting 32 in
29  // order to work on all processors.
30  enum { kChannelAlignment = 32 };
31
32  // Create an AudioBuffer whose channel data is copied from |data|. For
33  // interleaved data, only the first buffer is used. For planar data, the
34  // number of buffers must be equal to |channel_count|. |frame_count| is the
35  // number of frames in each buffer. |data| must not be null and |frame_count|
36  // must be >= 0.
37  //
38  // TODO(jrummell): Compute duration rather than pass it in.
39  static scoped_refptr<AudioBuffer> CopyFrom(SampleFormat sample_format,
40                                             ChannelLayout channel_layout,
41                                             int channel_count,
42                                             int sample_rate,
43                                             int frame_count,
44                                             const uint8* const* data,
45                                             const base::TimeDelta timestamp,
46                                             const base::TimeDelta duration);
47
48  // Create an AudioBuffer with |frame_count| frames. Buffer is allocated, but
49  // not initialized. Timestamp and duration are set to kNoTimestamp().
50  static scoped_refptr<AudioBuffer> CreateBuffer(SampleFormat sample_format,
51                                                 ChannelLayout channel_layout,
52                                                 int channel_count,
53                                                 int sample_rate,
54                                                 int frame_count);
55
56  // Create an empty AudioBuffer with |frame_count| frames.
57  static scoped_refptr<AudioBuffer> CreateEmptyBuffer(
58      ChannelLayout channel_layout,
59      int channel_count,
60      int sample_rate,
61      int frame_count,
62      const base::TimeDelta timestamp,
63      const base::TimeDelta duration);
64
65  // Create a AudioBuffer indicating we've reached end of stream.
66  // Calling any method other than end_of_stream() on the resulting buffer
67  // is disallowed.
68  static scoped_refptr<AudioBuffer> CreateEOSBuffer();
69
70  // Copy frames into |dest|. |frames_to_copy| is the number of frames to copy.
71  // |source_frame_offset| specifies how many frames in the buffer to skip
72  // first. |dest_frame_offset| is the frame offset in |dest|. The frames are
73  // converted from their source format into planar float32 data (which is all
74  // that AudioBus handles).
75  void ReadFrames(int frames_to_copy,
76                  int source_frame_offset,
77                  int dest_frame_offset,
78                  AudioBus* dest);
79
80  // Trim an AudioBuffer by removing |frames_to_trim| frames from the start.
81  // Timestamp and duration are adjusted to reflect the fewer frames.
82  // Note that repeated calls to TrimStart() may result in timestamp() and
83  // duration() being off by a few microseconds due to rounding issues.
84  void TrimStart(int frames_to_trim);
85
86  // Trim an AudioBuffer by removing |frames_to_trim| frames from the end.
87  // Duration is adjusted to reflect the fewer frames.
88  void TrimEnd(int frames_to_trim);
89
90  // Return the number of channels.
91  int channel_count() const { return channel_count_; }
92
93  // Return the number of frames held.
94  int frame_count() const { return adjusted_frame_count_; }
95
96  // Return the sample rate.
97  int sample_rate() const { return sample_rate_; }
98
99  // Return the channel layout.
100  ChannelLayout channel_layout() const { return channel_layout_; }
101
102  base::TimeDelta timestamp() const { return timestamp_; }
103  base::TimeDelta duration() const { return duration_; }
104  void set_timestamp(base::TimeDelta timestamp) { timestamp_ = timestamp; }
105  void set_duration(base::TimeDelta duration) { duration_ = duration; }
106
107  // If there's no data in this buffer, it represents end of stream.
108  bool end_of_stream() const { return end_of_stream_; }
109
110  // Access to the raw buffer for ffmpeg to write directly to. Data for planar
111  // data is grouped by channel. There is only 1 entry for interleaved formats.
112  const std::vector<uint8*>& channel_data() const { return channel_data_; }
113
114 private:
115  friend class base::RefCountedThreadSafe<AudioBuffer>;
116
117  // Allocates aligned contiguous buffer to hold all channel data (1 block for
118  // interleaved data, |channel_count| blocks for planar data), copies
119  // [data,data+data_size) to the allocated buffer(s). If |data| is null, no
120  // data is copied. If |create_buffer| is false, no data buffer is created (or
121  // copied to).
122  AudioBuffer(SampleFormat sample_format,
123              ChannelLayout channel_layout,
124              int channel_count,
125              int sample_rate,
126              int frame_count,
127              bool create_buffer,
128              const uint8* const* data,
129              const base::TimeDelta timestamp,
130              const base::TimeDelta duration);
131
132  virtual ~AudioBuffer();
133
134  const SampleFormat sample_format_;
135  const ChannelLayout channel_layout_;
136  const int channel_count_;
137  const int sample_rate_;
138  int adjusted_frame_count_;
139  int trim_start_;
140  const bool end_of_stream_;
141  base::TimeDelta timestamp_;
142  base::TimeDelta duration_;
143
144  // Contiguous block of channel data.
145  scoped_ptr<uint8, base::AlignedFreeDeleter> data_;
146
147  // For planar data, points to each channels data.
148  std::vector<uint8*> channel_data_;
149
150  DISALLOW_IMPLICIT_CONSTRUCTORS(AudioBuffer);
151};
152
153}  // namespace media
154
155#endif  // MEDIA_BASE_AUDIO_BUFFER_H_
156