v1.8.0: Audio 代码重构与低功耗优化 (#943)

* Reconstruct Audio Code

* Remove old IoT implementation

* Add MQTT-UDP documentation

* OTA升级失败时，可以继续使用

main/audio/codecs/es8388_audio_codec.h

@@ -0,0 +1,37 @@
+#ifndef _ES8388_AUDIO_CODEC_H
+#define _ES8388_AUDIO_CODEC_H
+
+#include "audio_codec.h"
+
+#include <driver/i2c_master.h>
+#include <esp_codec_dev.h>
+#include <esp_codec_dev_defaults.h>
+
+class Es8388AudioCodec : public AudioCodec {
+private:
+    const audio_codec_data_if_t* data_if_ = nullptr;
+    const audio_codec_ctrl_if_t* ctrl_if_ = nullptr;
+    const audio_codec_if_t* codec_if_ = nullptr;
+    const audio_codec_gpio_if_t* gpio_if_ = nullptr;
+
+    esp_codec_dev_handle_t output_dev_ = nullptr;
+    esp_codec_dev_handle_t input_dev_ = nullptr;
+    gpio_num_t pa_pin_ = GPIO_NUM_NC;
+
+    void CreateDuplexChannels(gpio_num_t mclk, gpio_num_t bclk, gpio_num_t ws, gpio_num_t dout, gpio_num_t din);
+
+    virtual int Read(int16_t* dest, int samples) override;
+    virtual int Write(const int16_t* data, int samples) override;
+
+public:
+    Es8388AudioCodec(void* i2c_master_handle, i2c_port_t i2c_port, int input_sample_rate, int output_sample_rate,
+        gpio_num_t mclk, gpio_num_t bclk, gpio_num_t ws, gpio_num_t dout, gpio_num_t din,
+        gpio_num_t pa_pin, uint8_t es8388_addr);
+    virtual ~Es8388AudioCodec();
+
+    virtual void SetOutputVolume(int volume) override;
+    virtual void EnableInput(bool enable) override;
+    virtual void EnableOutput(bool enable) override;
+};
+
+#endif // _ES8388_AUDIO_CODEC_H