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

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>

1 files changed, 17 insertions, 16 deletions

diff --git a/src/multimedia/audio/qaudiobuffer.h b/src/multimedia/audio/qaudiobuffer.h
index 14718cb38..ac16e2182 100644
--- a/src/multimedia/audio/qaudiobuffer.h
+++ b/src/multimedia/audio/qaudiobuffer.h
@@ -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