Downsample4x for 96Khz sample rate in I2S slave mode

usermods/audioreactive/audio_reactive.h

@@ -337,7 +337,7 @@ static float   lastFftCalc[NUM_GEQ_CHANNELS] = {0.0f};                // backup
 
 #if !defined(CONFIG_IDF_TARGET_ESP32C3)
 // audio source parameters and constant
-constexpr SRate_t SAMPLE_RATE = 22050;        // Base sample rate in Hz - 22Khz is a standard rate. Physical sample time -> 23ms
+constexpr SRate_t SAMPLE_RATE = 96000;        // Base sample rate in Hz - 22Khz is a standard rate. Physical sample time -> 23ms
 //constexpr SRate_t SAMPLE_RATE = 16000;        // 16kHz - use if FFTtask takes more than 20ms. Physical sample time -> 32ms
 //constexpr SRate_t SAMPLE_RATE = 20480;        // Base sample rate in Hz - 20Khz is experimental.    Physical sample time -> 25ms
 //constexpr SRate_t SAMPLE_RATE = 10240;        // Base sample rate in Hz - previous default.         Physical sample time -> 50ms

usermods/audioreactive/audio_source.h

@@ -187,6 +187,7 @@ class AudioSource {
     bool _i2sMaster;                // when false, ESP32 will be in I2S SLAVE mode (for devices that only operate in MASTER mode). Only works in newer IDF >= 4.4.x
     float _sampleScale;             // pre-scaling factor for I2S samples
     I2S_datatype newSampleBuffer[I2S_SAMPLES_MAX+4] = { 0 }; // global buffer for i2s_read
+    I2S_datatype newSampleBuffer4x[(I2S_SAMPLES_MAX*4)+4] = { 0 }; // global buffer for i2s_read
 };
 
 /* Basic I2S microphone source
@@ -195,12 +196,12 @@ class AudioSource {
 */
 class I2SSource : public AudioSource {
   public:
-    I2SSource(SRate_t sampleRate, int blockSize, float sampleScale = 1.0f, bool i2sMaster=true) :
+    I2SSource(SRate_t sampleRate, int blockSize, float sampleScale = 1.0f, bool i2sMaster=false) :
       AudioSource(sampleRate, blockSize, sampleScale, i2sMaster) {
       _config = {
         .mode = i2sMaster ? i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX) : i2s_mode_t(I2S_MODE_SLAVE | I2S_MODE_RX),
-        .sample_rate = _sampleRate,
-        .bits_per_sample = I2S_SAMPLE_RESOLUTION,  // slave mode: may help to set this to 96000, as the other side (master) controls sample rates
+        .sample_rate = _sampleRate, // slave mode: may help to set this to 96000, as the other side (master) controls sample rates
+        .bits_per_sample = I2S_SAMPLE_RESOLUTION,  
         .channel_format = I2S_MIC_CHANNEL,
 #if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 2, 0)
         .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S),
@@ -383,9 +384,17 @@ class I2SSource : public AudioSource {
 
         memset(buffer, 0, sizeof(float) * num_samples);  // clear output buffer
         I2S_datatype *newSamples = newSampleBuffer; // use global input buffer
+        I2S_datatype *newSamples_buff = newSampleBuffer4x; // use oversampling global input buffer
+
         if (num_samples > I2S_SAMPLES_MAX) num_samples = I2S_SAMPLES_MAX; // protect the buffer from overflow
 
-        err = i2s_read(I2S_NUM_0, (void *)newSamples, num_samples * sizeof(I2S_datatype), &bytes_read, portMAX_DELAY);
+        if (_sampleRate == 96000) {  
+          num_samples *= 4;
+          err = i2s_read(I2S_NUM_0, (void *)newSamples_buff, num_samples * sizeof(I2S_datatype), &bytes_read, portMAX_DELAY);
+        } else {
+          err = i2s_read(I2S_NUM_0, (void *)newSamples, num_samples * sizeof(I2S_datatype), &bytes_read, portMAX_DELAY);
+        }
+
         if (err != ESP_OK) {
           DEBUGSR_PRINTF("Failed to get samples: %d\n", err);
           return;
@@ -397,6 +406,15 @@ class I2SSource : public AudioSource {
           return;
         }
 
+        if (_sampleRate == 96000) {
+          int current = 0;
+          for (int i = 0; i < 2048; i += 4) {
+            newSamples[current] = newSamples_buff[i];
+            current++;
+          }
+          num_samples /= 4; // back to 512 samples
+        }
+
         // Store samples in sample buffer and update DC offset
         for (int i = 0; i < num_samples; i++) {