ESP32 实时语音通信（互联网对讲机）

功能是APP与ESP32 建立实时语音通讯。

最近刚完成ESP32-CAM与ANDROID视频流直播，遗憾的是0.5-0.8秒的延迟，虽然能凑合用但是明显不够完美。原因大概是ESP32-CAM性能问题，要么是OV2640的解码速度不够快，若能搞定语音通讯也打算换M5试试，或者OV7670据说速度快一些。
音频实时通讯这块我的想法是：
MAX9814->ESP32-WIFI-SERVER->RTMP->ANDROID->EAR
我也不是很确定这个方案行不行，毕竟没有什么可以参考的东西，这里我的疑惑是实时通讯一定要用RTMP吗？下面的代码感兴趣的朋友可以一起研究一下。

#include <Arduino.h>
#include <WiFi.h>
#include <driver/adc.h>

#define AUDIO_BUFFER_MAX 800

uint8_t audioBuffer[AUDIO_BUFFER_MAX];
uint8_t transmitBuffer[AUDIO_BUFFER_MAX];
uint32_t bufferPointer = 0;

const char* ssid     = "SSID";
const char* password = "PASSWORD";
const char* host     = "SERVER IP ADDRESS";

bool transmitNow = false;

WiFiClient client;

hw_timer_t * timer = NULL; // our timer
portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED; 

void IRAM_ATTR onTimer() {
portENTER_CRITICAL_ISR(&timerMux); 
// says that we want to run critical 
// code and don't want to be interrupted
int adcVal = adc1_get_voltage(ADC1_CHANNEL_0); // reads the ADC
uint8_t value = map(adcVal, 0 , 4096, 0, 255); // converts the value to 
// 0..255 (8bit)

audioBuffer[bufferPointer] = value; // stores the value
bufferPointer++;

if (bufferPointer == AUDIO_BUFFER_MAX) { // when the buffer is full
bufferPointer = 0;
memcpy(transmitBuffer, audioBuffer, AUDIO_BUFFER_MAX); // copy buffer 
// into a second buffer
transmitNow = true; // sets the value true so we know that we can 
// transmit now
}
portEXIT_CRITICAL_ISR(&timerMux); // says that we have run our critical 
// code
}


void setup() {
Serial.begin(115200);

WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
}

Serial.println("");
Serial.println("WiFi connected");
Serial.println("MY IP address: ");
Serial.println(WiFi.localIP());

adc1_config_width(ADC_WIDTH_12Bit); // configure the analogue to digital 
// converter
adc1_config_channel_atten(ADC1_CHANNEL_0, ADC_ATTEN_0db); // connects the 
// ADC 1 with channel 0 (GPIO 36)
Serial.println("ADC Configured.");
const int port = 4444;
while (!client.connect(host, port)) {
Serial.println("connection failed");
delay(1000);
}

Serial.println("connected to server");

timer = timerBegin(0, 80, true); // 80 Prescaler
timerAttachInterrupt(timer, &onTimer, true); // binds the handling 
// function to our timer 
timerAlarmWrite(timer, 125, true);
timerAlarmEnable(timer);

}

void loop() {
if (transmitNow) { // checks if the buffer is full
transmitNow = false;
client.write((const uint8_t *)audioBuffer, sizeof(audioBuffer)); // 
// sending the buffer to our server

}
}