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32 #include "AudioChannel.h"
33 #include <wtf/Noncopyable.h>
34 #include <wtf/PassOwnPtr.h>
35 #include <wtf/Vector.h>
39 // An AudioBus represents a collection of one or more AudioChannels.
40 // The data layout is "planar" as opposed to "interleaved".
41 // An AudioBus with one channel is mono, an AudioBus with two channels is stereo, etc.
43 WTF_MAKE_NONCOPYABLE(AudioBus);
48 ChannelCenter = 2, // center and mono are the same
51 ChannelSurroundLeft = 4,
52 ChannelSurroundRight = 5,
57 // Can define non-standard layouts here
60 // allocate indicates whether or not to initially have the AudioChannels created with managed storage.
61 // Normal usage is to pass true here, in which case the AudioChannels will memory-manage their own storage.
62 // If allocate is false then setChannelMemory() has to be called later on for each channel before the AudioBus is useable...
63 AudioBus(unsigned numberOfChannels, size_t length, bool allocate = true);
65 // Tells the given channel to use an externally allocated buffer.
66 void setChannelMemory(unsigned channelIndex, float* storage, size_t length);
69 unsigned numberOfChannels() const { return m_channels.size(); }
71 AudioChannel* channel(unsigned channel) { return m_channels[channel].get(); }
72 const AudioChannel* channel(unsigned channel) const { return const_cast<AudioBus*>(this)->m_channels[channel].get(); }
73 AudioChannel* channelByType(unsigned type);
75 // Number of sample-frames
76 size_t length() const { return m_length; }
78 // Sample-rate : 0.0 if unknown or "don't care"
79 double sampleRate() const { return m_sampleRate; }
80 void setSampleRate(double sampleRate) { m_sampleRate = sampleRate; }
82 // Zeroes all channels.
85 // Returns true if the channel count and frame-size match.
86 bool topologyMatches(const AudioBus &sourceBus) const;
88 // Creates a new buffer from a range in the source buffer.
89 // 0 may be returned if the range does not fit in the sourceBuffer
90 static PassOwnPtr<AudioBus> createBufferFromRange(AudioBus* sourceBuffer, unsigned startFrame, unsigned endFrame);
92 // Scales all samples by the same amount.
93 void scale(double scale);
95 // Master gain for this bus - used with sumWithGainFrom() below
96 void setGain(double gain) { m_busGain = gain; }
97 double gain() { return m_busGain; }
99 void reset() { m_isFirstTime = true; } // for de-zippering
101 // Assuming sourceBus has the same topology, copies sample data from each channel of sourceBus to our corresponding channel.
102 void copyFrom(const AudioBus &sourceBus);
104 // Sums the sourceBus into our bus with unity gain.
105 // Our own internal gain m_busGain is ignored.
106 void sumFrom(const AudioBus &sourceBus);
108 // Copy or sum each channel from sourceBus into our corresponding channel.
109 // We scale by targetGain (and our own internal gain m_busGain), performing "de-zippering" to smoothly change from *lastMixGain to (targetGain*m_busGain).
110 // The caller is responsible for setting up lastMixGain to point to storage which is unique for every "stream" which will be summed to this bus.
111 // This represents the dezippering memory.
112 void copyWithGainFrom(const AudioBus &sourceBus, double* lastMixGain, double targetGain);
113 void sumWithGainFrom(const AudioBus &sourceBus, double* lastMixGain, double targetGain);
115 // Returns maximum absolute value across all channels (useful for normalization).
116 float maxAbsValue() const;
118 // Makes maximum absolute value == 1.0 (if possible).
121 static PassOwnPtr<AudioBus> loadPlatformResource(const char* name, double sampleRate);
126 void processWithGainFrom(const AudioBus &sourceBus, double* lastMixGain, double targetGain, bool sumToBus);
127 void processWithGainFromMonoStereo(const AudioBus &sourceBus, double* lastMixGain, double targetGain, bool sumToBus);
131 Vector<OwnPtr<AudioChannel> > m_channels;
137 double m_sampleRate; // 0.0 if unknown or N/A