some failed experiments

Author: pschatzmann

sandbox/.DS_Store

@@ -0,0 +1,8 @@
+# A2DP Sink writing AAC files to SD Drive
+
+Usually the A2DP Sink is just sending the audio data to I2S. However we can send the output somwhere else.
+
+## Warning
+
+The example is crashing because there is not enugh stack space 
+

sandbox/a2dp-file_aac/README.md

@@ -0,0 +1,61 @@
+#include "Arduino.h"
+#include <SPI.h>
+#include <SD.h>
+#include "AudioTools.h"
+#include "BluetoothA2DPSink.h"
+
+// configuration
+const int sd_ss_pin = 4;
+
+// common data
+BluetoothA2DPSink a2dp_sink;
+File sound_file;
+AACEncoder *encoder;
+
+// detrmines the next file name
+char* nextFileName(){
+    static int idx;
+    static char[10] result;
+    sprintf(result,"F%000d", ++idx);
+    return result;
+}
+
+// opens a new file 
+void openFile() {
+    Serial.println("Recording next file...");
+    // save and cleanup of last file
+    sound_file.close();
+    if encoder != nullptr delete encoder;
+
+    // new file
+    dataFile = SD.open(nextFileName(), FILE_WRITE);
+    encoder = new AACEncoder(dataFile);
+    encoder->begin();
+}
+
+// Get the audio data from A2DP to save it in a file
+void read_data_stream(const uint8_t *data, uint32_t length) {
+    if (encoder!=nullptr) encoder.write(data, len);
+}
+
+// Handle meta data changes
+void avrc_metadata_callback(uint8_t data1, const uint8_t *data2) {
+    Serial.printf("AVRC metadata rsp: attribute id 0x%x, %s\n", data1, data2);
+    openFile()
+}
+
+void setup() {
+    Serial.begin(115200);
+
+    // setup A2DP
+    a2dp_sink.set_stream_reader(read_data_stream);
+    a2dp_sink.set_avrc_metadata_callback(avrc_metadata_callback);
+    a2dp_sink.start("AAC-Recorder");
+
+    // Setup SD 
+    SD.begin(sd_ss_pin);
+}
+
+
+void loop() {
+}

sandbox/a2dp-file_aac/a2dp-file_aac.ino

@@ -15,3 +15,8 @@ The ADS1015 is a 12 bit ADC which is connected via I2C.
 | ADDR    | GND  
 | ALRT    | -
 | A0      | Analog Source (e.g. Electic Guitar) 
+
+
+## Conclusion
+
+The sampling rate is too low to be usefull.

sandbox/ads1015-i2s/README.md

@@ -0,0 +1,16 @@
+# Stream In Memory Midi to A2DP Bluetooth using the ESP8266Audio Library
+
+The ESP32 can store only a limited amount of RAW data fully in the memory: Usually it's just sufficient for a couple of seconds. The memory wise most efficient file format is MIDI! By using MIDI we can easiy store one or even multiple pieces of music in the Flash Memory.  
+
+We can play MIDI with the [ESP8266Audio](https://github.com/earlephilhower/ESP8266Audio) library.
+
+And the nice thing: there is no need for a SD drive or any other additional hardware!
+
+## Compile Settings
+
+Set the Partition Scheme to Huge APP
+
+
+## Warning
+The quality is pretty bad ! 
+Reason to be investigated...