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Clarify API/docs by introducing the audio "frame", and add helpers.

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The frame is the interleaved set of one sample for each channel.  Add
some docs and some methods that make working with samples a bit more
convenient.

Adjusted QAudioBuffer to use these helper functions and terminology.

Change-Id: I96db48e659561972d6de2aa19893d29f9a828cd3
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>
This commit is contained in:
Michael Goddard
2012-07-10 14:26:58 +10:00
committed by Qt by Nokia
parent 68079a5e22
commit 4d13a15bae
7 changed files with 318 additions and 81 deletions
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33
src/multimedia/audio/qaudiobuffer.h
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@@ -65,7 +65,7 @@ public:
QAudioBuffer(QAbstractAudioBuffer *provider);
QAudioBuffer(const QAudioBuffer &other);
QAudioBuffer(const QByteArray &data, const QAudioFormat &format, qint64 startTime = -1);
QAudioBuffer(int numSamples, const QAudioFormat &format, qint64 startTime = -1); // Initialized to empty
QAudioBuffer(int numFrames, const QAudioFormat &format, qint64 startTime = -1); // Initialized to empty
QAudioBuffer& operator=(const QAudioBuffer &other);
@@ -75,6 +75,7 @@ public:
QAudioFormat format() const;
int frameCount() const;
int sampleCount() const;
int byteCount() const;
@@ -93,23 +94,23 @@ public:
void *data(); // detaches
// Structures for easier access to stereo data
template <typename T> struct StereoSampleDefault { enum { Default = 0 }; };
template <typename T> struct StereoFrameDefault { enum { Default = 0 }; };
template <typename T> struct StereoSample {
template <typename T> struct StereoFrame {
StereoSample()
: left(T(StereoSampleDefault<T>::Default))
, right(T(StereoSampleDefault<T>::Default))
StereoFrame()
: left(T(StereoFrameDefault<T>::Default))
, right(T(StereoFrameDefault<T>::Default))
{
}
StereoSample(T leftSample, T rightSample)
StereoFrame(T leftSample, T rightSample)
: left(leftSample)
, right(rightSample)
{
}
StereoSample& operator=(const StereoSample &other)
StereoFrame& operator=(const StereoFrame &other)
{
// Two straight assigns is probably
// cheaper than a conditional check on
@@ -123,14 +124,14 @@ public:
T right;
T average() const {return (left + right) / 2;}
void clear() {left = right = T(StereoSampleDefault<T>::Default);}
void clear() {left = right = T(StereoFrameDefault<T>::Default);}
};
typedef StereoSample<unsigned char> S8U;
typedef StereoSample<signed char> S8S;
typedef StereoSample<unsigned short> S16U;
typedef StereoSample<signed short> S16S;
typedef StereoSample<float> S32F;
typedef StereoFrame<unsigned char> S8U;
typedef StereoFrame<signed char> S8S;
typedef StereoFrame<unsigned short> S16U;
typedef StereoFrame<signed short> S16S;
typedef StereoFrame<float> S32F;
template <typename T> const T* constData() const {
return static_cast<const T*>(constData());
@@ -145,8 +146,8 @@ private:
QAudioBufferPrivate *d;
};
template <> struct QAudioBuffer::StereoSampleDefault<unsigned char> { enum { Default = 128 }; };
template <> struct QAudioBuffer::StereoSampleDefault<unsigned short> { enum { Default = 32768 }; };
template <> struct QAudioBuffer::StereoFrameDefault<unsigned char> { enum { Default = 128 }; };
template <> struct QAudioBuffer::StereoFrameDefault<unsigned short> { enum { Default = 32768 }; };
QT_END_NAMESPACE