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/audio_codec.cc

@@ -0,0 +1,72 @@
+#include "audio_codec.h"
+#include "board.h"
+#include "settings.h"
+
+#include <esp_log.h>
+#include <cstring>
+#include <driver/i2s_common.h>
+
+#define TAG "AudioCodec"
+
+AudioCodec::AudioCodec() {
+}
+
+AudioCodec::~AudioCodec() {
+}
+
+void AudioCodec::OutputData(std::vector<int16_t>& data) {
+    Write(data.data(), data.size());
+}
+
+bool AudioCodec::InputData(std::vector<int16_t>& data) {
+    int samples = Read(data.data(), data.size());
+    if (samples > 0) {
+        return true;
+    }
+    return false;
+}
+
+void AudioCodec::Start() {
+    Settings settings("audio", false);
+    output_volume_ = settings.GetInt("output_volume", output_volume_);
+    if (output_volume_ <= 0) {
+        ESP_LOGW(TAG, "Output volume value (%d) is too small, setting to default (10)", output_volume_);
+        output_volume_ = 10;
+    }
+
+    if (tx_handle_ != nullptr) {
+        ESP_ERROR_CHECK(i2s_channel_enable(tx_handle_));
+    }
+
+    if (rx_handle_ != nullptr) {
+        ESP_ERROR_CHECK(i2s_channel_enable(rx_handle_));
+    }
+
+    EnableInput(true);
+    EnableOutput(true);
+    ESP_LOGI(TAG, "Audio codec started");
+}
+
+void AudioCodec::SetOutputVolume(int volume) {
+    output_volume_ = volume;
+    ESP_LOGI(TAG, "Set output volume to %d", output_volume_);
+    
+    Settings settings("audio", true);
+    settings.SetInt("output_volume", output_volume_);
+}
+
+void AudioCodec::EnableInput(bool enable) {
+    if (enable == input_enabled_) {
+        return;
+    }
+    input_enabled_ = enable;
+    ESP_LOGI(TAG, "Set input enable to %s", enable ? "true" : "false");
+}
+
+void AudioCodec::EnableOutput(bool enable) {
+    if (enable == output_enabled_) {
+        return;
+    }
+    output_enabled_ = enable;
+    ESP_LOGI(TAG, "Set output enable to %s", enable ? "true" : "false");
+}