audio_buffer.h revision 010d83a9304c5a91596085d917d248abff47903a 
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  static scoped_refptr<AudioBuffer> CopyFrom(SampleFormat sample_format,
38                                             ChannelLayout channel_layout,
39                                             int channel_count,
40                                             int sample_rate,
41                                             int frame_count,
42                                             const uint8* const* data,
43                                             const base::TimeDelta timestamp);
44
45  // Create an AudioBuffer with |frame_count| frames. Buffer is allocated, but
46  // not initialized. Timestamp and duration are set to kNoTimestamp().
47  static scoped_refptr<AudioBuffer> CreateBuffer(SampleFormat sample_format,
48                                                 ChannelLayout channel_layout,
49                                                 int channel_count,
50                                                 int sample_rate,
51                                                 int frame_count);
52
53  // Create an empty AudioBuffer with |frame_count| frames.
54  static scoped_refptr<AudioBuffer> CreateEmptyBuffer(
55      ChannelLayout channel_layout,
56      int channel_count,
57      int sample_rate,
58      int frame_count,
59      const base::TimeDelta timestamp);
60
61  // Create a AudioBuffer indicating we've reached end of stream.
62  // Calling any method other than end_of_stream() on the resulting buffer
63  // is disallowed.
64  static scoped_refptr<AudioBuffer> CreateEOSBuffer();
65
66  // Copy frames into |dest|. |frames_to_copy| is the number of frames to copy.
67  // |source_frame_offset| specifies how many frames in the buffer to skip
68  // first. |dest_frame_offset| is the frame offset in |dest|. The frames are
69  // converted from their source format into planar float32 data (which is all
70  // that AudioBus handles).
71  void ReadFrames(int frames_to_copy,
72                  int source_frame_offset,
73                  int dest_frame_offset,
74                  AudioBus* dest);
75
76  // Trim an AudioBuffer by removing |frames_to_trim| frames from the start.
77  // Timestamp and duration are adjusted to reflect the fewer frames.
78  // Note that repeated calls to TrimStart() may result in timestamp() and
79  // duration() being off by a few microseconds due to rounding issues.
80  void TrimStart(int frames_to_trim);
81
82  // Trim an AudioBuffer by removing |frames_to_trim| frames from the end.
83  // Duration is adjusted to reflect the fewer frames.
84  void TrimEnd(int frames_to_trim);
85
86  // Trim an AudioBuffer by removing |end - start| frames from [|start|, |end|).
87  // Even if |start| is zero, timestamp() is not adjusted, only duration().
88  void TrimRange(int start, int end);
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
106  // If there's no data in this buffer, it represents end of stream.
107  bool end_of_stream() const { return end_of_stream_; }
108
109  // Access to the raw buffer for ffmpeg to write directly to. Data for planar
110  // data is grouped by channel. There is only 1 entry for interleaved formats.
111  const std::vector<uint8*>& channel_data() const { return channel_data_; }
112
113 private:
114  friend class base::RefCountedThreadSafe<AudioBuffer>;
115
116  // Allocates aligned contiguous buffer to hold all channel data (1 block for
117  // interleaved data, |channel_count| blocks for planar data), copies
118  // [data,data+data_size) to the allocated buffer(s). If |data| is null, no
119  // data is copied. If |create_buffer| is false, no data buffer is created (or
120  // copied to).
121  AudioBuffer(SampleFormat sample_format,
122              ChannelLayout channel_layout,
123              int channel_count,
124              int sample_rate,
125              int frame_count,
126              bool create_buffer,
127              const uint8* const* data,
128              const base::TimeDelta timestamp);
129
130  virtual ~AudioBuffer();
131
132  const SampleFormat sample_format_;
133  const ChannelLayout channel_layout_;
134  const int channel_count_;
135  const int sample_rate_;
136  int adjusted_frame_count_;
137  int trim_start_;
138  const bool end_of_stream_;
139  base::TimeDelta timestamp_;
140  base::TimeDelta duration_;
141
142  // Contiguous block of channel data.
143  scoped_ptr<uint8, base::AlignedFreeDeleter> data_;
144
145  // For planar data, points to each channels data.
146  std::vector<uint8*> channel_data_;
147
148  DISALLOW_IMPLICIT_CONSTRUCTORS(AudioBuffer);
149};
150
151}  // namespace media
152
153#endif  // MEDIA_BASE_AUDIO_BUFFER_H_
154