【ESP32音视频传输】①用I2S通过内部DAC或MAX98357A播放音乐/录音数据及接受网络广播

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文章目录

I2S介绍

我这里只是简单介绍下，具体介绍及使用教程可看：https://diyi0t.com/i2s-sound-tutorial-for-esp32/

I2S用于收发音频信号，有三根线组成：
①串行时钟 (SCK)也称为位时钟线 (BCLK)：用于在同一周期内获取所有组件。串行时钟的频率定义为：频率 = 采样率 * 每通道位数 * 通道数，例如对一个wav录音文件：
采样率：44.1 kHz
每通道位数：16
通道数：2
则串行时钟的频率为 44.1 kHz * 16 * 2 = 1.411 MHz。
②字选择 (WS)或帧选择 (FS) 线：
如果 WS = 0 → 使用通道 1（左通道）
如果 WS = 1 → 使用通道 2（右通道）
③串行数据 (SD)线：用于传输数据

ESP32有两个I2S接口，并且ESP32内部有两个8位的DAC分别对应GPIO25和GPIO26
（ESP8266没内部DAC，如果要播放录音需要外加MAX98357A）

注：而由于内部DAC方式声音太小，所以本实验优先考虑使用MAX98357A，对于内部DAC输出直接调用第三方库，而不直接对i2s就行配置了（主要原因是我直接配置内部DAC的i2s输出的声音很杂，肯定是哪里没配好，只能用第三方库了，等我搞懂了再更新吧）

一、使用外部DAC即MAX98357A播放录音

1.播放内存的录音数据

提示：主要是参考了https://www.xtronical.com/i2s-ep2/

完整示例可下载：https://www.xtronical.com/wp-content/uploads/2020/08/PlayWav.zip
我这里只是修改了一下i2s_num，以及对一些重要的注释翻译成中文

// Includes#include"driver/i2s.h"// 适用于ESP32的I2S库#include"WavData.h"// 把WAV格式的录音数据的bytes保存到WavData中//  Global Variables/objects    staticconsti2s_port_t i2s_num = I2S_NUM_1;// i2s port number，注意，如果是用内部DAC必须用I2S_NUM_0unsignedconstchar* TheData;uint32_t DataIdx=0;// index offset into "TheData" for current  data t send to I2SstructWavHeader_Struct{//   RIFF Section    char RIFFSectionID[4];// Letters "RIFF"uint32_t Size;// Size of entire file less 8char RiffFormat[4];// Letters "WAVE"//   Format Section    char FormatSectionID[4];// letters "fmt"uint32_t FormatSize;// Size of format section less 8uint16_t FormatID;// 1=uncompressed PCMuint16_t NumChannels;// 1=mono,2=stereouint32_t SampleRate;// 44100, 16000, 8000 etc.uint32_t ByteRate;// =SampleRate * Channels * (BitsPerSample/8)uint16_t BlockAlign;// =Channels * (BitsPerSample/8)uint16_t BitsPerSample;// 8,16,24 or 32// Data Sectionchar DataSectionID[4];// The letters "data"uint32_t DataSize;// Size of the data that follows}WavHeader;//------------------------------------------------------------------------------------------------------------------------//------------------------------------------------------------------------------------------------------------------------// I2S configuration structuresstaticconsti2s_config_t i2s_config ={.mode =(i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX),.sample_rate =44100,//设置采样率，但由于预先不知道WavData的录音数据的采样率，后面解码后会通过i2s_set_sample_rates修改.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,.communication_format =(i2s_comm_format_t)(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,// high interrupt priority.dma_buf_count =8,// 8 buffers.dma_buf_len =1024,// 1K per buffer, so 8K of buffer space.use_apll=0,.tx_desc_auto_clear= true,.fixed_mclk=-1};// These are the physical wiring connections to our I2S decoder board/chip from the esp32, there are other connections// required for the chips mentioned at the top (but not to the ESP32), please visit the page mentioned at the top for// further information regarding these other connections.staticconsti2s_pin_config_t pin_config ={.bck_io_num =27,// 时钟口，对应于MAX38357A的BCLK.ws_io_num =26,// 用于声道选择，对应于MAX38357A的LRC.data_out_num =25,// ESP32的音频输出口, 对应于MAX38357A的DIN.data_in_num = I2S_PIN_NO_CHANGE      // ESP32的音频输入接口，本例未用到};//------------------------------------------------------------------------------------------------------------------------voidsetup(){
    Serial.begin(115200);memcpy(&WavHeader,&WavData,44);// Copy the header part of the wav data into our structureDumpWAVHeader(&WavHeader);// Dump the header data to serial, optional!if(ValidWavData(&WavHeader)){i2s_driver_install(i2s_num,&i2s_config,0,NULL);// ESP32 will allocated resources to run I2Si2s_set_pin(i2s_num,&pin_config);// Tell it the pins you will be usingi2s_set_sample_rates(i2s_num, WavHeader.SampleRate);//set sample rate 
      TheData=WavData;// set to start of data  
      TheData+=44;}else// end code herewhile(true);}voidloop(){size_t BytesWritten;// Returned by the I2S write routine, we are not interested in it// 这里可选择每次发32bit的数据，也就是4 bytesi2s_write(i2s_num,TheData+DataIdx,4,&BytesWritten,portMAX_DELAY); 
  DataIdx+=4;// increase the data index to next two 16 bit values (4 bytes)if(DataIdx>=WavHeader.DataSize)// If we gone past end of data reset back to beginning
    DataIdx=0;}

bool ValidWavData(WavHeader_Struct* Wav){if(memcmp(Wav->RIFFSectionID,"RIFF",4)!=0){    
    Serial.print("Invlaid data - Not RIFF format");return false;}if(memcmp(Wav->RiffFormat,"WAVE",4)!=0){
    Serial.print("Invlaid data - Not Wave file");return false;}if(memcmp(Wav->FormatSectionID,"fmt",3)!=0){
    Serial.print("Invlaid data - No format section found");return false;}if(memcmp(Wav->DataSectionID,"data",4)!=0){
    Serial.print("Invlaid data - data section not found");return false;}if(Wav->FormatID!=1){
    Serial.print("Invlaid data - format Id must be 1");return false;}if(Wav->FormatSize!=16){
    Serial.print("Invlaid data - format section size must be 16.");return false;}if((Wav->NumChannels!=1)&(Wav->NumChannels!=2)){
    Serial.print("Invlaid data - only mono or stereo permitted.");return false;}if(Wav->SampleRate>48000){
    Serial.print("Invlaid data - Sample rate cannot be greater than 48000");return false;}if((Wav->BitsPerSample!=8)&(Wav->BitsPerSample!=16)){
    Serial.print("Invlaid data - Only 8 or 16 bits per sample permitted.");return false;}return true;}voidDumpWAVHeader(WavHeader_Struct* Wav){if(memcmp(Wav->RIFFSectionID,"RIFF",4)!=0){
    Serial.print("Not a RIFF format file - ");PrintData(Wav->RIFFSectionID,4);return;}if(memcmp(Wav->RiffFormat,"WAVE",4)!=0){
    Serial.print("Not a WAVE file - ");PrintData(Wav->RiffFormat,4);return;}if(memcmp(Wav->FormatSectionID,"fmt",3)!=0){
    Serial.print("fmt ID not present - ");PrintData(Wav->FormatSectionID,3);return;}if(memcmp(Wav->DataSectionID,"data",4)!=0){
    Serial.print("data ID not present - ");PrintData(Wav->DataSectionID,4);return;}// All looks good, dump the data
  Serial.print("Total size :");Serial.println(Wav->Size);
  Serial.print("Format section size :");Serial.println(Wav->FormatSize);
  Serial.print("Wave format :");Serial.println(Wav->FormatID);
  Serial.print("Channels :");Serial.println(Wav->NumChannels);
  Serial.print("Sample Rate :");Serial.println(Wav->SampleRate);
  Serial.print("Byte Rate :");Serial.println(Wav->ByteRate);
  Serial.print("Block Align :");Serial.println(Wav->BlockAlign);
  Serial.print("Bits Per Sample :");Serial.println(Wav->BitsPerSample);
  Serial.print("Data Size :");Serial.println(Wav->DataSize);}voidPrintData(constchar* Data,uint8_t NumBytes){for(uint8_t i=0;i<NumBytes;i++)
      Serial.print(Data[i]); 
      Serial.println();}

对应的接线方式如图（可在代码的pin_config 中更改）：

对于如何把后缀名为.wav的录音文件转化为WavData.h，可利用wsl的命令行：xxd -i xxx.wav xxx.h

2.使用第三方库ESP8266Audio

下载地址：https://github.com/earlephilhower/ESP8266Audio 

本例基于：https://diyi0t.com/i2s-sound-tutorial-for-esp32/

先下载ESP8266Audio的库zip文件，并在Arduino中安装此第三方库

#include"AudioGeneratorAAC.h"#include"AudioOutputI2S.h"#include"AudioFileSourcePROGMEM.h"#include"sampleaac.h"

AudioFileSourcePROGMEM *in;
AudioGeneratorAAC *aac;
AudioOutputI2S *out;voidsetup(){
  Serial.begin(115200);

  in = new AudioFileSourcePROGMEM(sampleaac,sizeof(sampleaac));
  aac = new AudioGeneratorAAC();
  out = new AudioOutputI2S();
  out ->SetGain(0.5);//设置音量0~1
  out ->SetPinout(27,33,32);//设置接到MAX98357A的引脚, GPIO27(串行时钟SCK)-->SCLK, GPIO33(字选择WS)-->LRC, GPIO32(串行数据SD)-->DIN
  aac->begin(in, out);}voidloop(){if(aac->isRunning()){
    aac->loop();}else{
    aac ->stop();
    Serial.printf("Sound Generator\n");delay(1000);}}

3.用第三方库ESP8266Audio接收网络广播

本例基于ESP8266Audio库的StreamMP3FromHTTPToSPDIF
然后修改一下代码，绑定MAX98357A，添加把广播源换成国内的

#include<Arduino.h>#ifdefESP32#include<WiFi.h>#else#include<ESP8266WiFi.h>#endif#include"AudioFileSourceICYStream.h"#include"AudioFileSourceBuffer.h"#include"AudioGeneratorMP3.h"//#include "AudioOutputI2SNoDAC.h"#include"AudioOutputI2S.h"//// Stream MP3 from HTTP to SPDIF//// To run, set your ESP8266 build to 160MHz, update the SSID info, and upload.// Note:// If using ESP8266 NodeMCU connect LED to RX pin and GND pin// Enter your WiFi setup here:#ifndefSTASSID#defineSTASSID"你的WiFi"#defineSTAPSK"WiFi密码"#endifconstchar* ssid = STASSID;constchar* password = STAPSK;// Examples URLs//const char *URL="http://kvbstreams.dyndns.org:8000/wkvi-am";// 换成了国内的广播源constchar*URL="http://lhttp.qingting.fm/live/4915/64k.mp3";// Stream URL of Logitech Media Server, aka LMS, Version: 8.2.0 (August 2021)// const char *URL="http://192.168.1.121:9000/stream.mp3";

AudioGeneratorMP3 *mp3;
AudioFileSourceICYStream *file;
AudioFileSourceBuffer *buff;// Output device is SPDIF
AudioOutputI2S *out;// Called when a metadata event occurs (i.e. an ID3 tag, an ICY block, etc.voidMDCallback(void*cbData,constchar*type, bool isUnicode,constchar*string){constchar*ptr = reinterpret_cast<constchar*>(cbData);(void) isUnicode;// Punt this ball for now// Note that the type and string may be in PROGMEM, so copy them to RAM for printfchar s1[32], s2[64];strncpy_P(s1, type,sizeof(s1));
  s1[sizeof(s1)-1]=0;strncpy_P(s2, string,sizeof(s2));
  s2[sizeof(s2)-1]=0;
  Serial.printf("METADATA(%s) '%s' = '%s'\n", ptr, s1, s2);
  Serial.flush();}// Called when there's a warning or error (like a buffer underflow or decode hiccup)voidStatusCallback(void*cbData,int code,constchar*string){constchar*ptr = reinterpret_cast<constchar*>(cbData);// Note that the string may be in PROGMEM, so copy it to RAM for printfchar s1[64];strncpy_P(s1, string,sizeof(s1));
  s1[sizeof(s1)-1]=0;
  Serial.printf("STATUS(%s) '%d' = '%s'\n", ptr, code, s1);
  Serial.flush();}voidsetup(){
  Serial.begin(115200);delay(1000);
  Serial.println("Connecting to WiFi");

  WiFi.disconnect();
  WiFi.softAPdisconnect(true);
  WiFi.mode(WIFI_STA);
  
  WiFi.begin(ssid, password);// Try foreverwhile(WiFi.status()!= WL_CONNECTED){
    Serial.println("...Connecting to WiFi");delay(1000);}
  Serial.println("Connected");

  audioLogger =&Serial;
  file = new AudioFileSourceICYStream(URL);// Commented out for performance issues with high rate MP3 stream//file->RegisterMetadataCB(MDCallback, (void*)"ICY");

  buff = new AudioFileSourceBuffer(file,4096);// Doubled form default 2048// Commented out for performance issues with high rate MP3 stream//buff->RegisterStatusCB(StatusCallback, (void*)"buffer");// Set SPDIF output
  out = new AudioOutputI2S();
  out ->SetGain(0.2);//设置音量
  out ->SetPinout(27,33,32);//设置接到MAX98357A的引脚, GPIO27(串行时钟SCK)-->SCLK, GPIO33(字选择WS)-->LRC, GPIO32(串行数据SD)-->DIN
  mp3 = new AudioGeneratorMP3();// Commented out for performance issues with high rate MP3 stream//mp3->RegisterStatusCB(StatusCallback, (void*)"mp3");

  mp3->begin(buff, out);}voidloop(){// Commented out//static int lastms = 0;if(mp3->isRunning()){/* Commented out
    if (millis()-lastms > 1000) {
      lastms = millis();
      Serial.printf("Running for %d ms...\n", lastms);
      Serial.flush();
     }
    */if(!mp3->loop()){
      mp3->stop();}}else{
    Serial.printf("MP3 done\n");// Restart ESP when streaming is done or erroreddelay(10000);

    ESP.restart();}}

不过我测试的时候发现声音总是会出现滴滴声，用这个库来接收直播流的效果并不好，但播放mp3文件的效果就很好，可以把URL换成http://mp3.jiuku.9ku.com/hot/2004/11-18/62878.mp3来试一下。

二、使用内部DAC播放录音

1.使用第三方库XT_DAC_Audio播放内存的录音数据

我尝试配置i2s来输出DAC，但一直有杂音，不知道是哪里的问题，这里就先直接用第三方库XT DAC
从下列链接下载.zip文件后用Arduino导入此第三方库即可

下载地址：https://www.xtronical.com/the-dacaudio-library-download-and-installation/ 

本例基于：https://www.yiboard.com/thread-1566-1-1.html 

然后打开例程PlayWav

// Playing a digital WAV recording repeatadly using the XTronical DAC Audio library// prints out to the serial monitor numbers counting up showing that the sound plays // independently of the main loop// See www.xtronical.com for write ups on sound, the hardware required and how to make// the wav files and include them in your code#include"SoundData.h"#include"XT_DAC_Audio.h"

XT_Wav_Class ForceWithYou(Force);// create an object of type XT_Wav_Class that is used by // the dac audio class (below), passing wav data as parameter.
                                      
XT_DAC_Audio_Class DacAudio(25,0);// Create the main player class object. // Use GPIO 25, one of the 2 DAC pins and timer 0uint32_t DemoCounter=0;// Just a counter to use in the serial monitor// not essential to playing the soundvoidsetup(){
  Serial.begin(115200);// Not needed for sound, just to demo printing to the serial// Monitor whilst the sound plays, ensure your serial monitor// speed is set to this speed also.}voidloop(){
  DacAudio.FillBuffer();// Fill the sound buffer with dataif(ForceWithYou.Playing==false)// if not playing,
    DacAudio.Play(&ForceWithYou);// play it, this will cause it to repeat and repeat...
  Serial.println(DemoCounter++);// Showing that the sound will play as well as your code running here.}

原例默认用GPIO25进行内部DAC输出，改成XT_DAC_Audio_Class DacAudio(26,0);就可以用GPIO26内部DAC输出了

2.使用第三方库ESP8266Audio

下载地址：https://github.com/earlephilhower/ESP8266Audio 

下载.zip文件并在Arduino中安装此第三方库后，打开例程PlayMODFromPROGMEMToDAC：

按照注释说的那样操作，把上一行反注释，下一行注释了由此实现内部DAC输出：

然后GPIO26接到喇叭的其中一根线上，喇叭的令一根线接地就行了

总结及演示

本文记录了ESP32播放音频的例程了，后续会陆续更新通过ESP32-cam传播视频的教程，实现ESP32cam+MAX9814实现视频和音乐播放，以及语音视频通话的功能，下面是esp32播放音乐视频的演示（esp32播放音乐视频）

esp32播放音乐视频