audio_bus.h revision 5821806d5e7f356e8fa4b058a389a808ea183019
1// Copyright (c) 2012 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_BUS_H_ 6#define MEDIA_BASE_AUDIO_BUS_H_ 7 8#include <vector> 9 10#include "base/memory/aligned_memory.h" 11#include "base/memory/scoped_ptr.h" 12#include "media/base/media_export.h" 13 14namespace media { 15class AudioParameters; 16 17// Scoped container for "busing" audio channel data around. Each channel is 18// stored in planar format and guaranteed to be aligned by kChannelAlignment. 19// AudioBus objects can be created normally or via wrapping. Normally, AudioBus 20// will dice up a contiguous memory block for channel data. When wrapped, 21// AudioBus instead routes requests for channel data to the wrapped object. 22class MEDIA_EXPORT AudioBus { 23 public: 24 // Guaranteed alignment of each channel's data; use 16-byte alignment for easy 25 // SSE optimizations. 26 enum { kChannelAlignment = 16 }; 27 28 // Creates a new AudioBus and allocates |channels| of length |frames|. Uses 29 // channels() and frames_per_buffer() from AudioParameters if given. 30 static scoped_ptr<AudioBus> Create(int channels, int frames); 31 static scoped_ptr<AudioBus> Create(const AudioParameters& params); 32 33 // Creates a new AudioBus with the given number of channels, but zero length. 34 // It's expected to be used with SetChannelData() and set_frames() to 35 // wrap externally allocated memory. 36 static scoped_ptr<AudioBus> CreateWrapper(int channels); 37 38 // Creates a new AudioBus from an existing channel vector. Does not transfer 39 // ownership of |channel_data| to AudioBus; i.e., |channel_data| must outlive 40 // the returned AudioBus. Each channel must be aligned by kChannelAlignment. 41 static scoped_ptr<AudioBus> WrapVector( 42 int frames, const std::vector<float*>& channel_data); 43 44 // Creates a new AudioBus by wrapping an existing block of memory. Block must 45 // be at least CalculateMemorySize() bytes in size. |data| must outlive the 46 // returned AudioBus. |data| must be aligned by kChannelAlignment. 47 static scoped_ptr<AudioBus> WrapMemory(int channels, int frames, void* data); 48 static scoped_ptr<AudioBus> WrapMemory(const AudioParameters& params, 49 void* data); 50 // Returns the required memory size to use the WrapMemory() method. 51 static int CalculateMemorySize(const AudioParameters& params); 52 53 // Calculates the required size for an AudioBus given the number of channels 54 // and frames. 55 static int CalculateMemorySize(int channels, int frames); 56 57 // Helper methods for converting an AudioBus from and to interleaved integer 58 // data. Expects interleaving to be [ch0, ch1, ..., chN, ch0, ch1, ...] with 59 // |bytes_per_sample| per value. Values are scaled and bias corrected during 60 // conversion. ToInterleaved() will also clip values to format range. 61 // Handles uint8, int16, and int32 currently. FromInterleaved() will zero out 62 // any unfilled frames when |frames| is less than frames(). 63 void FromInterleaved(const void* source, int frames, int bytes_per_sample); 64 void ToInterleaved(int frames, int bytes_per_sample, void* dest) const; 65 66 // Similar to FromInterleaved() above, but meant for streaming sources. Does 67 // not zero out remaining frames, the caller is responsible for doing so using 68 // ZeroFramesPartial(). Frames are deinterleaved from the start of |source| 69 // to channel(x)[start_frame]. 70 void FromInterleavedPartial(const void* source, int start_frame, int frames, 71 int bytes_per_sample); 72 73 // Helper method for copying channel data from one AudioBus to another. Both 74 // AudioBus object must have the same frames() and channels(). 75 void CopyTo(AudioBus* dest) const; 76 77 // Returns a raw pointer to the requested channel. Pointer is guaranteed to 78 // have a 16-byte alignment. Warning: Do not rely on having sane (i.e. not 79 // inf, nan, or between [-1.0, 1.0]) values in the channel data. 80 float* channel(int channel) { return channel_data_[channel]; } 81 const float* channel(int channel) const { return channel_data_[channel]; } 82 void SetChannelData(int channel, float* data); 83 84 int channels() const { return channel_data_.size(); } 85 int frames() const { return frames_; } 86 void set_frames(int frames); 87 88 // Helper method for zeroing out all channels of audio data. 89 void Zero(); 90 void ZeroFrames(int frames); 91 void ZeroFramesPartial(int start_frame, int frames); 92 93 private: 94 friend class scoped_ptr<AudioBus>; 95 ~AudioBus(); 96 97 AudioBus(int channels, int frames); 98 AudioBus(int channels, int frames, float* data); 99 AudioBus(int frames, const std::vector<float*>& channel_data); 100 explicit AudioBus(int channels); 101 102 // Helper method for building |channel_data_| from a block of memory. |data| 103 // must be at least BlockSize() bytes in size. 104 void BuildChannelData(int channels, int aligned_frame, float* data); 105 106 // Contiguous block of channel memory. 107 scoped_ptr_malloc<float, base::ScopedPtrAlignedFree> data_; 108 109 std::vector<float*> channel_data_; 110 int frames_; 111 112 // Protect SetChannelData() and set_frames() for use by CreateWrapper(). 113 bool can_set_channel_data_; 114 115 DISALLOW_COPY_AND_ASSIGN(AudioBus); 116}; 117 118} // namespace media 119 120#endif // MEDIA_BASE_AUDIO_BUS_H_ 121