How to stream video over HTTP using ESP32-CAM

Projects General Guidance
1

I've just had an ESP32-CAM and I found that there are very few tutorials on programming the camera. All I found is people showing how to upload codes (e.g. CameraWebServer from ESP32 core) and not teaching how to program them. I need to finish a project urgently, and trying to understand the codes takes a long time given how it includes face recognition, etcetera.

Right now I just need a bare minimum for ESP32-CAM to stream live feed from the OV2640 camera to a client browser. The only helpful tutorial I found is this and probably the simplest I can find. The tutorial shows how to configure the camera, initiate a web server, and send an image to the client.

From what I understand, the client has to make a HTTP request to be able to get data from the server, so how do I get the server to stream information without the client requesting it?

Looking back to the CameraWebServer example, I found an interesting function, startCameraServer(); which probably be the key to that, it derives from the app_httpd.cpp source code, and again it is very long and I don't understand much that was going on.

This is the code from the tutorial tho:

#include "WiFi.h"
#include "ESPAsyncWebServer.h"
#include "esp_camera.h"

#define PWDN_GPIO_NUM     32
#define RESET_GPIO_NUM    -1
#define XCLK_GPIO_NUM      0
#define SIOD_GPIO_NUM     26
#define SIOC_GPIO_NUM     27

#define Y9_GPIO_NUM       35
#define Y8_GPIO_NUM       34
#define Y7_GPIO_NUM       39
#define Y6_GPIO_NUM       36
#define Y5_GPIO_NUM       21
#define Y4_GPIO_NUM       19
#define Y3_GPIO_NUM       18
#define Y2_GPIO_NUM        5
#define VSYNC_GPIO_NUM    25
#define HREF_GPIO_NUM     23
#define PCLK_GPIO_NUM     22

const char* ssid = "***";
const char* password = "***";
AsyncWebServer server(80);

bool initCamera(){
  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = Y2_GPIO_NUM;
  config.pin_d1 = Y3_GPIO_NUM;
  config.pin_d2 = Y4_GPIO_NUM;
  config.pin_d3 = Y5_GPIO_NUM;
  config.pin_d4 = Y6_GPIO_NUM;
  config.pin_d5 = Y7_GPIO_NUM;
  config.pin_d6 = Y8_GPIO_NUM;
  config.pin_d7 = Y9_GPIO_NUM;
  config.pin_xclk = XCLK_GPIO_NUM;
  config.pin_pclk = PCLK_GPIO_NUM;
  config.pin_vsync = VSYNC_GPIO_NUM;
  config.pin_href = HREF_GPIO_NUM;
  config.pin_sscb_sda = SIOD_GPIO_NUM;
  config.pin_sscb_scl = SIOC_GPIO_NUM;
  config.pin_pwdn = PWDN_GPIO_NUM;
  config.pin_reset = RESET_GPIO_NUM;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;
  config.frame_size = FRAMESIZE_VGA;
  config.jpeg_quality = 12;
  config.fb_count = 1;

  esp_err_t result = esp_camera_init(&config);

  if(result != ESP_OK){
    return false;
  }
  return true;
}

void setup() {
  Serial.begin(115200);
  if(!initCamera()){
    Serial.printf("Failed to Initialize OV2640 Camera");
    return;
  }
  WiFi.begin(ssid,password);
  while(WiFi.status() != WL_CONNECTED){
    Serial.print(".");
    delay(300);
  }
  Serial.println(WiFi.localIP());
  
  server.on("/picture",HTTP_GET,[] (AsyncWebServerRequest * request){
    camera_fb_t * frame = NULL;
    frame = esp_camera_fb_get();
    request->send_P(200, "image/jpeg", (const uint8_t*)frame->buf,frame->len);
    esp_camera_fb_return(frame);
  });

  server.begin();
}

void loop() {
}