iOS audio: avoided slow check for sample rate support and implemented latency getters.

modules/juce_audio_devices/native/juce_android_OpenSL.cpp

@@ -80,7 +80,7 @@ public:
 
     Array<double> getAvailableSampleRates() override
     {
-        static const double rates[]       = { 8000.0, 16000.0, 32000.0, 44100.0, 48000.0 };
+        static const double rates[] = { 8000.0, 16000.0, 32000.0, 44100.0, 48000.0 };
         return Array<double> (rates, numElementsInArray (rates));
     }
 

modules/juce_audio_devices/native/juce_ios_Audio.cpp

@@ -67,7 +67,12 @@ public:
         return s;
     }
 
-    Array<double> getAvailableSampleRates() override    { return sampleRates; }
+    Array<double> getAvailableSampleRates() override
+    {
+        // can't find a good way to actually ask the device for which of these it supports..
+        static const double rates[] = { 8000.0, 16000.0, 22050.0, 32000.0, 44100.0, 48000.0 };
+        return Array<double> (rates, numElementsInArray (rates));
+    }
 
     Array<int> getAvailableBufferSizes() override
     {
@@ -79,7 +84,7 @@ public:
         return r;
     }
 
-    int getDefaultBufferSize() override                 { return 1024; }
+    int getDefaultBufferSize() override         { return 1024; }
 
     String open (const BigInteger& inputChannelsWanted,
                  const BigInteger& outputChannelsWanted,
@@ -117,10 +122,9 @@ public:
         AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, routingChangedStatic, this);
 
         fixAudioRouteIfSetToReceiver();
-        updateDeviceInfo();
 
         setSessionFloat64Property (kAudioSessionProperty_PreferredHardwareSampleRate, targetSampleRate);
-        updateSampleRates();
+        updateDeviceInfo();
 
         setSessionFloat32Property (kAudioSessionProperty_PreferredHardwareIOBufferDuration, preferredBufferSize / sampleRate);
         updateCurrentBufferSize();
@@ -162,8 +166,15 @@ public:
     BigInteger getActiveOutputChannels() const override    { return activeOutputChans; }
     BigInteger getActiveInputChannels() const override     { return activeInputChans; }
 
-    int getOutputLatencyInSamples() override               { return 0; } //xxx
-    int getInputLatencyInSamples() override                { return 0; } //xxx
+    int getOutputLatencyInSamples() override    { return getLatency (kAudioSessionProperty_CurrentHardwareOutputLatency); }
+    int getInputLatencyInSamples() override     { return getLatency (kAudioSessionProperty_CurrentHardwareInputLatency); }
+
+    int getLatency (AudioSessionPropertyID propID)
+    {
+        Float32 latency = 0;
+        getSessionProperty (propID, latency);
+        return roundToInt (latency * getCurrentSampleRate());
+    }
 
     void start (AudioIODeviceCallback* newCallback) override
     {
@@ -201,7 +212,6 @@ private:
     //==================================================================================================
     CriticalSection callbackLock;
     Float64 sampleRate;
-    Array<Float64> sampleRates;
     int numInputChannels, numOutputChannels;
     int preferredBufferSize, actualBufferSize;
     bool isRunning;
@@ -322,38 +332,6 @@ private:
         getSessionProperty (kAudioSessionProperty_AudioInputAvailable, audioInputIsAvailable);
     }
 
-    void updateSampleRates()
-    {
-        getSessionProperty (kAudioSessionProperty_CurrentHardwareSampleRate, sampleRate);
-
-        sampleRates.clear();
-        sampleRates.add (sampleRate);
-
-        const int commonSampleRates[] = { 8000, 16000, 22050, 32000, 44100, 48000 };
-
-        for (int i = 0; i < numElementsInArray (commonSampleRates); ++i)
-        {
-            Float64 rate = (Float64) commonSampleRates[i];
-
-            if (rate != sampleRate)
-            {
-                setSessionFloat64Property (kAudioSessionProperty_PreferredHardwareSampleRate, rate);
-
-                Float64 actualSampleRate = 0.0;
-                getSessionProperty (kAudioSessionProperty_CurrentHardwareSampleRate, actualSampleRate);
-
-                if (actualSampleRate == rate)
-                    sampleRates.add (actualSampleRate);
-            }
-        }
-
-        DefaultElementComparator<Float64> comparator;
-        sampleRates.sort (comparator);
-
-        setSessionFloat64Property (kAudioSessionProperty_PreferredHardwareSampleRate, sampleRate);
-        getSessionProperty (kAudioSessionProperty_CurrentHardwareSampleRate, sampleRate);
-    }
-
     void updateCurrentBufferSize()
     {
         Float32 bufferDuration = sampleRate > 0 ? (Float32) (preferredBufferSize / sampleRate) : 0.0f;