diff audio/AudioCallbackPlaySource.h @ 554:4be200469a9c 3.0-integration

Merge from branch bqresample

--- a/audio/AudioCallbackPlaySource.h	Tue Dec 06 15:59:06 2016 +0000
+++ b/audio/AudioCallbackPlaySource.h	Fri Dec 09 18:01:55 2016 +0000
@@ -39,6 +39,10 @@
     class RubberBandStretcher;
 }
 
+namespace breakfastquay {
+    class ResamplerWrapper;
+}
+
 class Model;
 class ViewManagerBase;
 class AudioGenerator;
@@ -121,6 +125,11 @@
     virtual void setSystemPlaybackTarget(breakfastquay::SystemPlaybackTarget *);
 
     /**
+     * Set the resampler wrapper, if one is in use.
+     */
+    virtual void setResamplerWrapper(breakfastquay::ResamplerWrapper *);
+    
+    /**
      * Set the block size of the target audio device.  This should be
      * called by the target class.
      */
@@ -136,7 +145,7 @@
 
     /**
      * Set the playback latency of the target audio device, in frames
-     * at the target sample rate.  This is the difference between the
+     * at the device sample rate.  This is the difference between the
      * frame currently "leaving the speakers" and the last frame (or
      * highest last frame across all channels) requested via
      * getSamples().  The default is zero.
@@ -161,7 +170,7 @@
      * Return the sample rate set by the target audio device (or the
      * source sample rate if the target hasn't set one).
      */
-    virtual sv_samplerate_t getTargetSampleRate() const;
+    sv_samplerate_t getDeviceSampleRate() const;
 
     /**
      * Indicate how many channels the target audio device was opened
@@ -194,30 +203,45 @@
      * to the play target.  This may be more than the source channel
      * count: for example, a mono source will provide 2 channels
      * after pan.
+     *
      * This may safely be called from a realtime thread.  Returns 0 if
      * there is no source yet available.
+     *
+     * override from AudioPlaySource
      */
-    int getTargetChannelCount() const;
+    virtual int getTargetChannelCount() const override;
 
     /**
      * ApplicationPlaybackSource equivalent of the above.
+     *
+     * override from breakfastquay::ApplicationPlaybackSource
      */
-    virtual int getApplicationChannelCount() const {
+    virtual int getApplicationChannelCount() const override {
         return getTargetChannelCount();
     }
     
     /**
-     * Get the actual sample rate of the source material.  This may
-     * safely be called from a realtime thread.  Returns 0 if there is
-     * no source yet available.
+     * Get the actual sample rate of the source material (the main
+     * model).  This may safely be called from a realtime thread.
+     * Returns 0 if there is no source yet available.
+     *
+     * When this changes, the AudioCallbackPlaySource notifies its
+     * ResamplerWrapper of the new sample rate so that it can resample
+     * correctly on the way to the device (which is opened at a fixed
+     * rate, see getApplicationSampleRate).
      */
-    virtual sv_samplerate_t getSourceSampleRate() const;
+    virtual sv_samplerate_t getSourceSampleRate() const override;
 
     /**
-     * ApplicationPlaybackSource equivalent of the above.
+     * ApplicationPlaybackSource interface method: get the sample rate
+     * at which the application wants the device to be opened. We
+     * always allow the device to open at its default rate, and then
+     * we resample if the audio is at a different rate. This avoids
+     * having to close and re-open the device to obtain consistent
+     * behaviour for consecutive sessions with different source rates.
      */
-    virtual int getApplicationSampleRate() const {
-        return int(round(getSourceSampleRate()));
+    virtual int getApplicationSampleRate() const override {
+        return 0;
     }
 
     /**
@@ -311,7 +335,7 @@
     int                               m_sourceChannelCount;
     sv_frame_t                        m_blockSize;
     sv_samplerate_t                   m_sourceSampleRate;
-    sv_samplerate_t                   m_targetSampleRate;
+    sv_samplerate_t                   m_deviceSampleRate;
     sv_frame_t                        m_playLatency;
     breakfastquay::SystemPlaybackTarget *m_target;
     double                            m_lastRetrievalTimestamp;
@@ -396,6 +420,7 @@
     QMutex m_mutex;
     QWaitCondition m_condition;
     FillThread *m_fillThread;
+    breakfastquay::ResamplerWrapper *m_resamplerWrapper; // I don't own this
 };
 
 #endif