Add pre-packaged dependency libraries (ESP32-audioI2S and PNGdec)

libraries/ESP32-audioI2S/examples/ES8388/ES8388.h

@@ -0,0 +1,27 @@
+#pragma once
+#include <stdint.h>
+
+class ES8388
+{
+
+    bool write_reg(uint8_t slave_add, uint8_t reg_add, uint8_t data);
+    bool read_reg(uint8_t slave_add, uint8_t reg_add, uint8_t &data);
+    bool identify(int32_t sda, int32_t scl, uint32_t frequency);
+
+public:
+    bool begin(int32_t sda = -1, int32_t scl = -1, uint32_t frequency = 400000U);
+
+    enum ES8388_OUT
+    {
+        ES_MAIN, // this is the DAC output volume (both outputs)
+        ES_OUT1, // this is the additional gain for OUT1
+        ES_OUT2  // this is the additional gain for OUT2
+    };
+
+    void SetVolumeSpeaker(uint8_t vol);
+    void SetVolumeHeadphone(uint8_t vol);
+
+    void mute(const ES8388_OUT out, const bool muted);
+    void volume(const ES8388_OUT out, const uint8_t vol);
+};
+