ChannelMixer: template for sum type

Author: pschatzmann

src/AudioTools/CoreAudio/BaseConverter.h

@@ -938,6 +938,41 @@ class ChannelDiff : public BaseConverter {
   int bits = 16;
 };
 
+
+/**
+ * @brief We mix all input channels in a datastream. E.g. if we have stereo input data
+ * we end up with 2 identical mono channels. 
+ * @author Phil Schatzmann
+ * @ingroup convert
+ * @tparam T
+ */
+template <typename T = int16_t, typename SumT = float>
+class ChannelMixer : public BaseConverter {
+ public:
+  ChannelMixer(int channels = 2) { this->channels = channels; }
+  size_t convert(uint8_t *data, size_t size) {
+    if (channels <= 1) return size;  // No mixing needed for single channel
+    T *srcT = (T *)data;
+    T *targetT = (T *)data;
+    int samples = size / sizeof(T);
+    assert(samples % channels == 0);
+    for (int j = 0; j < samples; j += channels) {
+      SumT sum = 0;
+      for (int ch = 0; ch < channels; ch++) {
+        sum += srcT[j + ch];
+      }
+      T avg = sum / channels;
+      for (int ch = 0; ch < channels; ch++) {
+        targetT[j + ch] = avg;
+      }
+    }
+    return size;
+  }
+
+ protected:
+  int channels = 2;
+};
+
 /**
  * @brief We average pairs of channels in a datastream.
  *  E.g. if we have 4 channels we end up with 2 channels.
@@ -951,7 +986,7 @@ class ChannelDiff : public BaseConverter {
  * @ingroup convert
  * @tparam T
  */
-template <typename T = int16_t>
+template <typename T = int16_t, typename AvgT = float>
 class ChannelAvgT : public BaseConverter {
  public:
   ChannelAvgT() {}
@@ -975,7 +1010,7 @@ class ChannelAvgT : public BaseConverter {
     for (int i = 0; i < sample_count; i++) {
       // *p_result++ = (*p_source++ + *p_source++) / 2; // Average the pair of
       // channels
-      auto tmp = *p_source++;
+      AvgT tmp = *p_source++;
       tmp += *p_source++;
       *p_result++ = tmp / 2;
     }
@@ -986,39 +1021,6 @@ class ChannelAvgT : public BaseConverter {
   }
 };
 
-/**
- * @brief We mix all input channels in a datastream. E.g. if we have stereo input data
- * we end up with 2 identical mono channels. 
- * @author Phil Schatzmann
- * @ingroup convert
- * @tparam T
- */
-template <typename T = int16_t, typename SumT = float>
-class ChannelMixer : public BaseConverter {
- public:
-  ChannelMixer(int channels = 2) { this->channels = channels; }
-  size_t convert(uint8_t *data, size_t size) {
-    if (channels <= 1) return size;  // No mixing needed for single channel
-    T *srcT = (T *)data;
-    T *targetT = (T *)data;
-    int samples = size / sizeof(T);
-    assert(samples % channels == 0);
-    for (int j = 0; j < samples; j += channels) {
-      SumT sum = 0;
-      for (int ch = 0; ch < channels; ch++) {
-        sum += srcT[j + ch];
-      }
-      T avg = sum / channels;
-      for (int ch = 0; ch < channels; ch++) {
-        targetT[j + ch] = avg;
-      }
-    }
-    return size;
-  }
-
- protected:
-  int channels = 2;
-};
 
 /**
  * @brief We average pairs of channels in a datastream.
@@ -1042,20 +1044,35 @@ class ChannelAvg : public BaseConverter {
   size_t convert(uint8_t *src, size_t size) { return convert(src, src, size); }
   size_t convert(uint8_t *target, uint8_t *src, size_t size) {
     switch (bits) {
+#ifdef PREFER_FIXEDPOINT
+      case 8: {
+        ChannelAvgT<int8_t, int16_t> ca8;
+        return ca8.convert(target, src, size);
+      }
+      case 16: {
+        ChannelAvgT<int16_t, int32_t> ca16;
+        return ca16.convert(target, src, size);
+      }
+      case 24: {
+        ChannelAvgT<int24_t, int32_t> ca24;
+        return ca24.convert(target, src, size);
+      }
+#else
       case 8: {
-        ChannelAvgT<int8_t> ca8;
+        ChannelAvgT<int8_t, float> ca8;
         return ca8.convert(target, src, size);
       }
       case 16: {
-        ChannelAvgT<int16_t> ca16;
+        ChannelAvgT<int16_t, float> ca16;
         return ca16.convert(target, src, size);
       }
       case 24: {
-        ChannelAvgT<int24_t> ca24;
+        ChannelAvgT<int24_t, float> ca24;
         return ca24.convert(target, src, size);
       }
+#endif
       case 32: {
-        ChannelAvgT<int32_t> ca32;
+        ChannelAvgT<int32_t, float> ca32;
         return ca32.convert(target, src, size);
       }
       default: {