Calculate current delay for a BlockInput correctly

Author: gamblor21

shared-bindings/audiodelays/Echo.c

@@ -33,7 +33,7 @@
 //|         samples_signed: bool = True,
 //|         channel_count: int = 1,
 //|     ) -> None:
-//|         """Create a Echo effect that echos an audio sample every set number of microseconds.
+//|         """Create a Echo effect that echos an audio sample every set number of milliseconds.
 //|
 //|         :param int max_delay_ms: The maximum delay the echo can be
 //|         :param BlockInput delay_ms: The current echo delay
@@ -132,7 +132,7 @@ static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(audiodelays_echo___exit___obj, 4, 4,
 
 
 //|     delay_ms: BlockInput
-//|     """Delay of the echo in microseconds. (read-only)"""
+//|     """Delay of the echo in milliseconds. (read-only)"""
 //|
 static mp_obj_t audiodelays_echo_obj_get_delay_ms(mp_obj_t self_in) {
     audiodelays_echo_obj_t *self = MP_OBJ_TO_PTR(self_in);

shared-module/audiodelays/Echo.c

@@ -86,10 +86,11 @@ void common_hal_audiodelays_echo_construct(audiodelays_echo_obj_t *self, uint32_
 
     // calculate current echo buffer size we use for the given delay
     mp_float_t f_delay_ms = synthio_block_slot_get(&self->delay_ms);
+    self->current_delay_ms = f_delay_ms;
     self->echo_buffer_len = self->sample_rate / 1000.0f * f_delay_ms * (self->channel_count * sizeof(uint16_t));
 
-    // read is where we store the incoming sample + previous echo
-    // write is what we send to the outgoing buffer
+    // read is where we read previous echo from delay_ms ago to play back now
+    // write is where the store the latest playing sample to echo back later
     self->echo_buffer_read_pos = self->buffer_len / sizeof(uint16_t);
     self->echo_buffer_write_pos = 0;
 }
@@ -119,17 +120,24 @@ void common_hal_audiodelays_echo_set_delay_ms(audiodelays_echo_obj_t *self, mp_o
     synthio_block_assign_slot(delay_ms, &self->delay_ms, MP_QSTR_delay_ms);
 
     mp_float_t f_delay_ms = synthio_block_slot_get(&self->delay_ms);
-    self->echo_buffer_len = self->sample_rate / 1000.0f * f_delay_ms * (self->channel_count * 2);// (self->bits_per_sample / 8));
 
-    uint32_t max_ebuf_length = self->echo_buffer_len / sizeof(uint16_t);
+    recalculate_delay(self, f_delay_ms);
+}
+
+void recalculate_delay(audiodelays_echo_obj_t *self, mp_float_t f_delay_ms) {
+    // Calculate the current echo buffer length in bytes
 
-    if (self->echo_buffer_read_pos > max_ebuf_length) {
-        self->echo_buffer_read_pos = 0;
-        self->echo_buffer_write_pos = max_ebuf_length - (self->buffer_len / sizeof(uint16_t));
-    } else if (self->echo_buffer_write_pos > max_ebuf_length) {
-        self->echo_buffer_read_pos = self->buffer_len / sizeof(uint16_t);
-        self->echo_buffer_write_pos = 0;
+    uint32_t new_echo_buffer_len = self->sample_rate / 1000.0f * f_delay_ms * sizeof(uint16_t);
+
+    // Check if our new echo is too long for our maximum buffer
+    if (new_echo_buffer_len > self->max_echo_buffer_len) {
+        return;
+    } else if (new_echo_buffer_len < 0.0) { // or too short!
+        return;
     }
+
+    self->echo_buffer_len = new_echo_buffer_len;
+    self->current_delay_ms = f_delay_ms;
 }
 
 mp_obj_t common_hal_audiodelays_echo_get_decay(audiodelays_echo_obj_t *self) {
@@ -250,6 +258,11 @@ audioio_get_buffer_result_t audiodelays_echo_get_buffer(audiodelays_echo_obj_t *
     mp_float_t mix = MIN(1.0, MAX(synthio_block_slot_get(&self->mix), 0.0));
     mp_float_t decay = MIN(1.0, MAX(synthio_block_slot_get(&self->decay), 0.0));
 
+    uint32_t delay_ms = (uint32_t)synthio_block_slot_get(&self->delay_ms);
+    if (self->current_delay_ms != delay_ms) {
+        recalculate_delay(self, delay_ms);
+    }
+
     // Switch our buffers to the other buffer
     self->last_buf_idx = !self->last_buf_idx;
 

shared-module/audiodelays/Echo.h

@@ -16,6 +16,7 @@ typedef struct {
     mp_obj_base_t base;
     uint32_t max_delay_ms;
     synthio_block_slot_t delay_ms;
+    uint32_t current_delay_ms;
     synthio_block_slot_t decay;
     synthio_block_slot_t mix;
 
@@ -44,6 +45,8 @@ typedef struct {
     mp_obj_t sample;
 } audiodelays_echo_obj_t;
 
+void recalculate_delay(audiodelays_echo_obj_t *self, mp_float_t f_delay_ms);
+
 void audiodelays_echo_reset_buffer(audiodelays_echo_obj_t *self,
     bool single_channel_output,
     uint8_t channel);