media/base/audio_buffer.h

   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
  18 namespace media {
  19 class 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.
  24 class 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_