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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef AudioChannel_h
#define AudioChannel_h
#include "AudioArray.h"
#include <wtf/PassOwnPtr.h>
namespace WebCore {
// An AudioChannel represents a buffer of non-interleaved floating-point audio samples.
// The PCM samples are normally assumed to be in a nominal range -1.0 -> +1.0
class AudioChannel {
WTF_MAKE_NONCOPYABLE(AudioChannel);
public:
// Memory can be externally referenced, or can be internally allocated with an AudioFloatArray.
// Reference an external buffer.
AudioChannel(float* storage, size_t length)
: m_length(length)
, m_rawPointer(storage)
, m_silent(false)
{
}
// Manage storage for us.
explicit AudioChannel(size_t length)
: m_length(length)
, m_rawPointer(0)
, m_silent(true)
{
m_memBuffer = adoptPtr(new AudioFloatArray(length));
}
// A "blank" audio channel -- must call set() before it's useful...
AudioChannel()
: m_length(0)
, m_rawPointer(0)
, m_silent(true)
{
}
// Redefine the memory for this channel.
// storage represents external memory not managed by this object.
void set(float* storage, size_t length)
{
m_memBuffer.clear(); // cleanup managed storage
m_rawPointer = storage;
m_length = length;
m_silent = false;
}
// How many sample-frames do we contain?
size_t length() const { return m_length; }
// resizeSmaller() can only be called with a new length <= the current length.
// The data stored in the bus will remain undisturbed.
void resizeSmaller(size_t newLength);
// Direct access to PCM sample data. Non-const accessor clears silent flag.
float* mutableData()
{
clearSilentFlag();
return m_rawPointer ? m_rawPointer : m_memBuffer->data();
}
const float* data() const { return m_rawPointer ? m_rawPointer : m_memBuffer->data(); }
// Zeroes out all sample values in buffer.
void zero()
{
if (m_silent)
return;
m_silent = true;
if (m_memBuffer.get())
m_memBuffer->zero();
else
memset(m_rawPointer, 0, sizeof(float) * m_length);
}
// Clears the silent flag.
void clearSilentFlag() { m_silent = false; }
bool isSilent() const { return m_silent; }
// Scales all samples by the same amount.
void scale(float scale);
// A simple memcpy() from the source channel
void copyFrom(const AudioChannel* sourceChannel);
// Copies the given range from the source channel.
void copyFromRange(const AudioChannel* sourceChannel, unsigned startFrame, unsigned endFrame);
// Sums (with unity gain) from the source channel.
void sumFrom(const AudioChannel* sourceChannel);
// Returns maximum absolute value (useful for normalization).
float maxAbsValue() const;
private:
size_t m_length;
float* m_rawPointer;
OwnPtr<AudioFloatArray> m_memBuffer;
bool m_silent;
};
} // WebCore
#endif // AudioChannel_h
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