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/media_export.h"
  15 #include "media/base/sample_format.h"
  16
  17 namespace media {
  18 class AudioBus;
  19
  20 // An audio buffer that takes a copy of the data passed to it, holds it, and
  21 // copies it into an AudioBus when needed. Also supports an end of stream
  22 // marker.
  23 class MEDIA_EXPORT AudioBuffer
  24     : public base::RefCountedThreadSafe<AudioBuffer> {
  25  public:
  26   // Alignment of each channel's data; this must match what ffmpeg expects
  27   // (which may be 0, 16, or 32, depending on the processor). Selecting 32 in
  28   // order to work on all processors.
  29   enum { kChannelAlignment = 32 };
  30
  31   // Create an AudioBuffer whose channel data is copied from |data|. For
  32   // interleaved data, only the first buffer is used. For planar data, the
  33   // number of buffers must be equal to |channel_count|. |frame_count| is the
  34   // number of frames in each buffer. |data| must not be null and |frame_count|
  35   // must be >= 0.
  36   //
  37   // TODO(jrummell): Compute duration rather than pass it in.
  38   static scoped_refptr<AudioBuffer> CopyFrom(SampleFormat sample_format,
  39                                              int channel_count,
  40                                              int frame_count,
  41                                              const uint8* const* data,
  42                                              const base::TimeDelta timestamp,
  43                                              const base::TimeDelta duration);
  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                                                  int channel_count,
  49                                                  int frame_count);
  50
  51   // Create an empty AudioBuffer with |frame_count| frames.
  52   static scoped_refptr<AudioBuffer> CreateEmptyBuffer(
  53       int channel_count,
  54       int frame_count,
  55       const base::TimeDelta timestamp,
  56       const base::TimeDelta duration);
  57
  58   // Create a AudioBuffer indicating we've reached end of stream.
  59   // Calling any method other than end_of_stream() on the resulting buffer
  60   // is disallowed.
  61   static scoped_refptr<AudioBuffer> CreateEOSBuffer();
  62
  63   // Copy frames into |dest|. |frames_to_copy| is the number of frames to copy.
  64   // |source_frame_offset| specifies how many frames in the buffer to skip
  65   // first. |dest_frame_offset| is the frame offset in |dest|. The frames are
  66   // converted from their source format into planar float32 data (which is all
  67   // that AudioBus handles).
  68   void ReadFrames(int frames_to_copy,
  69                   int source_frame_offset,
  70                   int dest_frame_offset,
  71                   AudioBus* dest);
  72
  73   // Trim an AudioBuffer by removing |frames_to_trim| frames from the start.
  74   // Timestamp and duration are adjusted to reflect the fewer frames.
  75   // Note that repeated calls to TrimStart() may result in timestamp() and
  76   // duration() being off by a few microseconds due to rounding issues.
  77   void TrimStart(int frames_to_trim);
  78
  79   // Trim an AudioBuffer by removing |frames_to_trim| frames from the end.
  80   // Duration is adjusted to reflect the fewer frames.
  81   void TrimEnd(int frames_to_trim);
  82
  83   // Return the number of channels.
  84   int channel_count() const { return channel_count_; }
  85
  86   // Return the number of frames held.
  87   int frame_count() const { return adjusted_frame_count_; }
  88
  89   // Access to constructor parameters.
  90   base::TimeDelta timestamp() const { return timestamp_; }
  91   base::TimeDelta duration() const { return duration_; }
  92
  93   // TODO(jrummell): Remove set_timestamp() and set_duration() once
  94   // DecryptingAudioDecoder::EnqueueFrames() is changed to set them when
  95   // creating the buffer. See http://crbug.com/255261.
  96   void set_timestamp(base::TimeDelta timestamp) { timestamp_ = timestamp; }
  97   void set_duration(base::TimeDelta duration) { duration_ = duration; }
  98
  99   // If there's no data in this buffer, it represents end of stream.
 100   bool end_of_stream() const { return end_of_stream_; }
 101
 102   // Access to the raw buffer for ffmpeg to write directly to. Data for planar
 103   // data is grouped by channel. There is only 1 entry for interleaved formats.
 104   const std::vector<uint8*>& channel_data() const { return channel_data_; }
 105
 106  private:
 107   friend class base::RefCountedThreadSafe<AudioBuffer>;
 108
 109   // Allocates aligned contiguous buffer to hold all channel data (1 block for
 110   // interleaved data, |channel_count| blocks for planar data), copies
 111   // [data,data+data_size) to the allocated buffer(s). If |data| is null, no
 112   // data is copied. If |create_buffer| is false, no data buffer is created (or
 113   // copied to).
 114   AudioBuffer(SampleFormat sample_format,
 115               int channel_count,
 116               int frame_count,
 117               bool create_buffer,
 118               const uint8* const* data,
 119               const base::TimeDelta timestamp,
 120               const base::TimeDelta duration);
 121
 122   virtual ~AudioBuffer();
 123
 124   const SampleFormat sample_format_;
 125   const int channel_count_;
 126   int adjusted_frame_count_;
 127   int trim_start_;
 128   const bool end_of_stream_;
 129   base::TimeDelta timestamp_;
 130   base::TimeDelta duration_;
 131
 132   // Contiguous block of channel data.
 133   scoped_ptr_malloc<uint8, base::ScopedPtrAlignedFree> data_;
 134
 135   // For planar data, points to each channels data.
 136   std::vector<uint8*> channel_data_;
 137
 138   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioBuffer);
 139 };
 140
 141 }  // namespace media
 142
 143 #endif  // MEDIA_BASE_AUDIO_BUFFER_H_