Tweaks to new audio path code:

1. Move lambda usage for RX to member functions (adds readability and possibly fixes #250).
2. Use sync as well as SNR/squelch setting to determine whether to let audio through (reduces extra noise in speakers).

src/freedv_interface.cpp

@@ -26,6 +26,33 @@
 #include "pipeline/FreeDVTransmitStep.h"
 #include "pipeline/FreeDVReceiveStep.h"
 
+using namespace std::placeholders;
+
+static const char* GetCurrentModeStrImpl_(int mode)
+{
+    switch(mode)
+    {
+        case FREEDV_MODE_700C:
+            return "700C";
+        case FREEDV_MODE_700D:
+            return "700D";
+        case FREEDV_MODE_700E:
+            return "700E";
+        case FREEDV_MODE_1600:
+            return "1600";
+        case FREEDV_MODE_2020:
+            return "2020";
+        case FREEDV_MODE_2020B:
+            return "2020B";
+        case FREEDV_MODE_800XA:
+            return "800XA";
+        case FREEDV_MODE_2400B:
+            return "2400B";
+        default:
+            return "unk";
+    }
+}
+
 FreeDVInterface::FreeDVInterface() :
     textRxFunc_(nullptr),
     singleRxThread_(false),
@@ -588,7 +615,24 @@ IPipelineStep* FreeDVInterface::createReceivePipeline(
         parallelSteps.push_back(recvStep);
     }
     
-    auto preProcessFn = [&](ParallelStep* stepObj) {
+    state->preProcessFn = std::bind(&FreeDVInterface::preProcessRxFn_, this, _1);
+    state->postProcessFn = std::bind(&FreeDVInterface::postProcessRxFn_, this, _1);
+        
+    auto parallelStep = new ParallelStep(
+        inputSampleRate,
+        outputSampleRate,
+        !singleRxThread_,
+        state->preProcessFn,
+        state->postProcessFn,
+        parallelSteps,
+        state
+    );
+    
+    return parallelStep;
+}
+
+int FreeDVInterface::preProcessRxFn_(ParallelStep* stepObj)
+{
     int rxIndex = 0;
     std::shared_ptr<ReceivePipelineState> state = std::static_pointer_cast<ReceivePipelineState>(stepObj->getState());
 
@@ -616,7 +660,8 @@ IPipelineStep* FreeDVInterface::createReceivePipeline(
     return -1;
 };
 
-    auto postProcessFn = [&](ParallelStep* stepObj) {
+int FreeDVInterface::postProcessRxFn_(ParallelStep* stepObj)
+{
     std::shared_ptr<ReceivePipelineState> state = std::static_pointer_cast<ReceivePipelineState>(stepObj->getState());
 
     // If the current RX mode is still sync'd, only let that one out.
@@ -648,7 +693,10 @@ IPipelineStep* FreeDVInterface::createReceivePipeline(
         }
         int snr = (int)(snrVals_[rxIndex]+0.5);
         
-            if (snr > maxSyncFound && tmpStats->sync != 0)
+        bool canUnsquelch = !squelchEnabled_ ||
+            (squelchEnabled_ && snr >= squelchVals_[rxIndex]);
+        
+        if (snr > maxSyncFound && tmpStats->sync != 0 && canUnsquelch)
         {
             maxSyncFound = snr;
             indexWithSync = rxIndex;
@@ -685,16 +733,3 @@ skipSyncCheck:
     
     return indexWithSync;
 };
-    
-    auto parallelStep = new ParallelStep(
-        inputSampleRate,
-        outputSampleRate,
-        !singleRxThread_,
-        preProcessFn,
-        postProcessFn,
-        parallelSteps,
-        state
-    );
-    
-    return parallelStep;
-}

src/freedv_interface.h

@@ -40,6 +40,7 @@
 #include <samplerate.h>
 
 class IPipelineStep;
+class ParallelStep;
 
 class FreeDVInterface
 {
@@ -120,6 +121,8 @@ private:
         std::function<int()> getChannelNoiseSnrFn;
         std::function<float()> getFreqOffsetFn;
         std::function<float*()> getSigPwrAvgFn;
+        std::function<int(ParallelStep*)> preProcessFn;
+        std::function<int(ParallelStep*)> postProcessFn;
     };
 
     struct FreeDVTextFnState
@@ -161,6 +164,9 @@ private:
     
     std::deque<reliable_text_t> reliableText_;
     std::string receivedReliableText_;
+    
+    int preProcessRxFn_(ParallelStep* ps);
+    int postProcessRxFn_(ParallelStep* ps);
 };
 
 #endif // CODEC2_INTERFACE_H