I2S Read support for channels = 1

Author: pschatzmann

src/AudioI2S/I2SESP32.h

@@ -88,8 +88,36 @@ class I2SBase {
 
     size_t readBytes(void *dest, size_t size_bytes){
       size_t result = 0;
-      if (i2s_read(i2s_num, dest, size_bytes, &result, portMAX_DELAY)!=ESP_OK){
-        LOGE(LOG_METHOD);
+      if (cfg.channels==2){
+        if (i2s_read(i2s_num, dest, size_bytes, &result, portMAX_DELAY)!=ESP_OK){
+          LOGE(LOG_METHOD);
+        }
+      } else if (cfg.channels==1){
+        // I2S has always 2 channels. We support to reduce it to 1
+        uint8_t temp[size_bytes*2];
+        if (i2s_read(i2s_num, temp, size_bytes*2, &result, portMAX_DELAY)!=ESP_OK){
+          LOGE(LOG_METHOD);
+        }
+        // convert to 1 channel
+        switch(cfg.bits_per_sample){
+          case 16: {
+            ChannelReducer<int16_t> reducer16(1, 2);
+            result = reducer16.convert((uint8_t*)dest,temp, result);
+            } break;
+          // case 24: {
+          //   ChannelReducer<int24_t> reducer24(1,2);
+          //   result = reducer24.convert((uint8_t*)dest,temp,result);
+          //   } break;
+          case 32: {
+            ChannelReducer<int32_t> reducer32(1, 2);
+            result = reducer32.convert((uint8_t*)dest, temp, result);
+            } break;
+          default:
+            LOGE("invalid bits_per_sample: %d", cfg.bits_per_sample);
+            break;
+        }
+      } else {
+        LOGE("Invalid channels: %d", cfg.channels);
       }
       return result;
     }

src/AudioTools/Converter.h

@@ -355,7 +355,7 @@ class ChannelReducer : public BaseConverter<T> {
     public:
         ChannelReducer() = default;
 
-        ChannelReducer(int channelCountOfSource, int channelCountOfTarget=1){
+        ChannelReducer(int channelCountOfTarget, int channelCountOfSource){
             from_channels = channelCountOfSource;
             to_channels = channelCountOfTarget;
         }
@@ -367,11 +367,15 @@ class ChannelReducer : public BaseConverter<T> {
         void setTargetChannels(int channelCountOfTarget) {
             to_channels = channelCountOfTarget;
         }
-        
+
         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) {
             int frame_count = size/(sizeof(T)*from_channels);
             size_t result_size=0;
-            T* result = (T*)src;
+            T* result = (T*)target;
             T* source = (T*)src;
             int reduceDiv = from_channels-to_channels+1;
 
@@ -398,6 +402,7 @@ class ChannelReducer : public BaseConverter<T> {
 };
 
 
+
 /**
  * @brief Combines multiple converters
  *