夜市小霸王

我的ESP32實做書籍：https://youyouyou.pixnet.net/blog/post/121105860
博客來網址：https://www.books.com.tw/products/0010901195

以往在ESP32CAM教學時，偶爾會遇到學生問說，為什麼只有一個人能看，我都會說這是單晶片的限制，心裡想說，一顆兩三百的單晶片能做Stream Webserver已經很厲害了，還要多人連線，會不會太強人所難。

不過有一次一位很好學的學生問：「老師，您說ESP32有雙核心，還能跑多執行緒，現在不能多人連線看影像是不是有點說不過去」。

心想似乎也是，我每次上課都會強調這顆晶片可以跑多執行緒，竟然如此應該來研究一下如何將單人連線程式改寫成多人連線。

不過在研究之前，先Google看看，哲學家都說：「不用重複造輪子」，就發現了這篇：https://www.hackster.io/anatoli-arkhipenko/multi-client-mjpeg-streaming-from-esp32-47768f，沒想到真的有大神已經寫好了，馬上把網址傳給那位好問的學生去測試看看，誰叫你愛問，沒想到一測試就成功了，太棒了。

後來又經過我們多次改寫及精簡，現在把輪子程式附上給大家。

三個客戶端同時連線：PCx2，手機x1，連線狀況非常好，多人連線也幾乎沒有延遲。

#include <WiFi.h>
#include <WebServer.h>
#include <WiFiClient.h>
#include <Arduino.h>
#include <pgmspace.h>
#include <stdio.h>
#include "esp_log.h"
#include "esp_attr.h"
#include "esp_camera.h"
#include <esp_bt.h>
#include <esp_wifi.h>
#include <esp_sleep.h>
#include <driver/rtc_io.h>

//Setup Your wifi
const char* ssid = "You";
const char* password = "0933932774";

//Define AI_Thinker Camera_pins
#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
#define APP_CPU 1
#define PRO_CPU 0

class OV2640
{
  public:
    OV2640() {
      fb = NULL;
    };
    ~OV2640() {
    };
    esp_err_t init(camera_config_t config);
    void run(void);
    size_t getSize(void);
    uint8_t *getfb(void);
    int getWidth(void);
    int getHeight(void);
    framesize_t getFrameSize(void);
    pixformat_t getPixelFormat(void);

    void setFrameSize(framesize_t size);
    void setPixelFormat(pixformat_t format);

  private:
    void runIfNeeded(); // grab a frame if we don't already have one
    // camera_framesize_t _frame_size;
    // camera_pixelformat_t _pixel_format;
    camera_config_t _cam_config;
    camera_fb_t *fb;
};

void OV2640::run(void)
{
  if (fb)
    //return the frame buffer back to the driver for reuse
    esp_camera_fb_return(fb);

  fb = esp_camera_fb_get();
}

void OV2640::runIfNeeded(void)
{
  if (!fb)
    run();
}

int OV2640::getWidth(void)
{
  runIfNeeded();
  return fb->width;
}

int OV2640::getHeight(void)
{
  runIfNeeded();
  return fb->height;
}

size_t OV2640::getSize(void)
{
  runIfNeeded();
  if (!fb)
    return 0; // FIXME - this shouldn't be possible but apparently the new cam board returns null sometimes?
  return fb->len;
}

uint8_t *OV2640::getfb(void)
{
  runIfNeeded();
  if (!fb)
    return NULL; // FIXME - this shouldn't be possible but apparently the new cam board returns null sometimes?

  return fb->buf;
}

framesize_t OV2640::getFrameSize(void)
{
  return _cam_config.frame_size;
}

void OV2640::setFrameSize(framesize_t size)
{
  _cam_config.frame_size = size;
}

pixformat_t OV2640::getPixelFormat(void)
{
  return _cam_config.pixel_format;
}

void OV2640::setPixelFormat(pixformat_t format)
{
  switch (format)
  {
    case PIXFORMAT_RGB565:
    case PIXFORMAT_YUV422:
    case PIXFORMAT_GRAYSCALE:
    case PIXFORMAT_JPEG:
      _cam_config.pixel_format = format;
      break;
    default:
      _cam_config.pixel_format = PIXFORMAT_GRAYSCALE;
      break;
  }
}

esp_err_t OV2640::init(camera_config_t config)
{
  memset(&_cam_config, 0, sizeof(_cam_config));
  memcpy(&_cam_config, &config, sizeof(config));

  esp_err_t err = esp_camera_init(&_cam_config);
  if (err != ESP_OK)
  {
    printf("Camera probe failed with error 0x%x", err);
    return err;
  }
  // ESP_ERROR_CHECK(gpio_install_isr_service(0));

  return ESP_OK;
} OV2640 cam;

WebServer server(80);

// ===== rtos task handles =========================
// Streaming is implemented with 3 tasks:
TaskHandle_t tMjpeg;   // handles client connections to the webserver
TaskHandle_t tCam;     // handles getting picture frames from the camera and storing them locally
TaskHandle_t tStream;  // actually streaming frames to all connected clients

// frameSync semaphore is used to prevent streaming buffer as it is replaced with the next frame
SemaphoreHandle_t frameSync = NULL;

// Queue stores currently connected clients to whom we are streaming
QueueHandle_t streamingClients;

// We will try to achieve 25 FPS frame rate
const int FPS = 25;

// We will handle web client requests every 50 ms (20 Hz)
const int WSINTERVAL = 50;

// ======== Server Connection Handler Task ==========================
void mjpegCB(void* pvParameters) {
  TickType_t xLastWakeTime;
  const TickType_t xFrequency = pdMS_TO_TICKS(WSINTERVAL);

  // Creating frame synchronization semaphore and initializing it
  frameSync = xSemaphoreCreateBinary();
  xSemaphoreGive( frameSync );

  // Creating a queue to track all connected clients
  streamingClients = xQueueCreate( 10, sizeof(WiFiClient*) );

  //=== setup section  ==================

  //  Creating RTOS task for grabbing frames from the camera
  xTaskCreatePinnedToCore(
    camCB,        // callback
    "cam",        // name
    4096,         // stacj size
    NULL,         // parameters
    2,            // priority
    &tCam,        // RTOS task handle
    APP_CPU);     // core

  //  Creating task to push the stream to all connected clients
  xTaskCreatePinnedToCore(
    streamCB,
    "strmCB",
    4096,
    NULL, //(void*) handler,
    2,
    &tStream,
    APP_CPU);

  //  Registering webserver handling routines
  server.on("/stream", HTTP_GET, handleJPGSstream);
  server.on("/jpg", HTTP_GET, handleJPG);
  server.onNotFound(handleNotFound);

  //  Starting webserver
  server.begin();

  //=== loop() section  ===================
  xLastWakeTime = xTaskGetTickCount();
  for (;;) {
    server.handleClient();

    //  After every server client handling request, we let other tasks run and then pause
    taskYIELD();
    vTaskDelayUntil(&xLastWakeTime, xFrequency);
  }
}

// Commonly used variables:
volatile size_t camSize;    // size of the current frame, byte
volatile char* camBuf;      // pointer to the current frame

// ==== RTOS task to grab frames from the camera =========================
void camCB(void* pvParameters) {

  TickType_t xLastWakeTime;

  //  A running interval associated with currently desired frame rate
  const TickType_t xFrequency = pdMS_TO_TICKS(1000 / FPS);

  // Mutex for the critical section of swithing the active frames around
  portMUX_TYPE xSemaphore = portMUX_INITIALIZER_UNLOCKED;

  //  Pointers to the 2 frames, their respective sizes and index of the current frame
  char* fbs[2] = { NULL, NULL };
  size_t fSize[2] = { 0, 0 };
  int ifb = 0;

  //=== loop() section  ===================
  xLastWakeTime = xTaskGetTickCount();

  for (;;) {

    //  Grab a frame from the camera and query its size
    cam.run();
    size_t s = cam.getSize();

    //  If frame size is more that we have previously allocated - request  125% of the current frame space
    if (s > fSize[ifb]) {
      fSize[ifb] = s * 4 / 3;
      fbs[ifb] = allocateMemory(fbs[ifb], fSize[ifb]);
    }

    //  Copy current frame into local buffer
    char* b = (char*) cam.getfb();
    memcpy(fbs[ifb], b, s);

    //  Let other tasks run and wait until the end of the current frame rate interval (if any time left)
    taskYIELD();
    vTaskDelayUntil(&xLastWakeTime, xFrequency);

    //  Only switch frames around if no frame is currently being streamed to a client
    //  Wait on a semaphore until client operation completes
    xSemaphoreTake( frameSync, portMAX_DELAY );

    //  Do not allow interrupts while switching the current frame
    taskENTER_CRITICAL(&xSemaphore);
    camBuf = fbs[ifb];
    camSize = s;
    ifb = (++ifb) & 1;  // this should produce 1, 0, 1, 0, 1 ... sequence
    taskEXIT_CRITICAL(&xSemaphore);

    //  Let anyone waiting for a frame know that the frame is ready
    xSemaphoreGive( frameSync );

    //  Technically only needed once: let the streaming task know that we have at least one frame
    //  and it could start sending frames to the clients, if any
    xTaskNotifyGive( tStream );

    //  Immediately let other (streaming) tasks run
    taskYIELD();

    //  If streaming task has suspended itself (no active clients to stream to)
    //  there is no need to grab frames from the camera. We can save some juice
    //  by suspedning the tasks
    if ( eTaskGetState( tStream ) == eSuspended ) {
      vTaskSuspend(NULL);  // passing NULL means "suspend yourself"
    }
  }
}

// ==== Memory allocator that takes advantage of PSRAM if present =======================
char* allocateMemory(char* aPtr, size_t aSize) {

  //  Since current buffer is too smal, free it
  if (aPtr != NULL) free(aPtr);

  size_t freeHeap = ESP.getFreeHeap();
  char* ptr = NULL;

  // If memory requested is more than 2/3 of the currently free heap, try PSRAM immediately
  if ( aSize > freeHeap * 2 / 3 ) {
    if ( psramFound() && ESP.getFreePsram() > aSize ) {
      ptr = (char*) ps_malloc(aSize);
    }
  }
  else {
    //  Enough free heap - let's try allocating fast RAM as a buffer
    ptr = (char*) malloc(aSize);

    //  If allocation on the heap failed, let's give PSRAM one more chance:
    if ( ptr == NULL && psramFound() && ESP.getFreePsram() > aSize) {
      ptr = (char*) ps_malloc(aSize);
    }
  }

  // Finally, if the memory pointer is NULL, we were not able to allocate any memory, and that is a terminal condition.
  if (ptr == NULL) {
    ESP.restart();
  }
  return ptr;
}

// ==== STREAMING ======================================================
const char HEADER[] = "HTTP/1.1 200 OK\r\n" \
                      "Access-Control-Allow-Origin: *\r\n" \
                      "Content-Type: multipart/x-mixed-replace; boundary=123456789000000000000987654321\r\n";
const char BOUNDARY[] = "\r\n--123456789000000000000987654321\r\n";
const char CTNTTYPE[] = "Content-Type: image/jpeg\r\nContent-Length: ";
const int hdrLen = strlen(HEADER);
const int bdrLen = strlen(BOUNDARY);
const int cntLen = strlen(CTNTTYPE);

//控制連線服務
void handleJPGSstream(void)
{
  //  Can only acommodate 10 clients. The limit is a default for WiFi connections
  if ( !uxQueueSpacesAvailable(streamingClients) ) return;

  //  Create a new WiFi Client object to keep track of this one
  WiFiClient* client = new WiFiClient();
  *client = server.client();

  //  Immediately send this client a header
  client->write(HEADER, hdrLen);
  client->write(BOUNDARY, bdrLen);

  // Push the client to the streaming queue
  xQueueSend(streamingClients, (void *) &client, 0);

  // Wake up streaming tasks, if they were previously suspended:
  if ( eTaskGetState( tCam ) == eSuspended ) vTaskResume( tCam );
  if ( eTaskGetState( tStream ) == eSuspended ) vTaskResume( tStream );
}

//處理連線服務
void streamCB(void * pvParameters) {
  char buf[16];
  TickType_t xLastWakeTime;
  TickType_t xFrequency;

  //  Wait until the first frame is captured and there is something to send
  //  to clients
  ulTaskNotifyTake( pdTRUE,          /* Clear the notification value before exiting. */
                    portMAX_DELAY ); /* Block indefinitely. */

  xLastWakeTime = xTaskGetTickCount();
  for (;;) {
    // Default assumption we are running according to the FPS
    xFrequency = pdMS_TO_TICKS(1000 / FPS);

    //  Only bother to send anything if there is someone watching
    UBaseType_t activeClients = uxQueueMessagesWaiting(streamingClients);
    if ( activeClients ) {
      // Adjust the period to the number of connected clients
      xFrequency /= activeClients;

      //  Since we are sending the same frame to everyone,
      //  pop a client from the the front of the queue
      WiFiClient *client;
      xQueueReceive (streamingClients, (void*) &client, 0);

      //  Check if this client is still connected.

      if (!client->connected()) {
        //  delete this client reference if s/he has disconnected
        //  and don't put it back on the queue anymore. Bye!
        delete client;
      }
      else {

        //  Ok. This is an actively connected client.
        //  Let's grab a semaphore to prevent frame changes while we
        //  are serving this frame
        xSemaphoreTake( frameSync, portMAX_DELAY );

        client->write(CTNTTYPE, cntLen);
        sprintf(buf, "%d\r\n\r\n", camSize);
        client->write(buf, strlen(buf));
        client->write((char*) camBuf, (size_t)camSize);
        client->write(BOUNDARY, bdrLen);

        // Since this client is still connected, push it to the end
        // of the queue for further processing
        xQueueSend(streamingClients, (void *) &client, 0);

        //  The frame has been served. Release the semaphore and let other tasks run.
        //  If there is a frame switch ready, it will happen now in between frames
        xSemaphoreGive( frameSync );
        taskYIELD();
      }
    }
    else {
      //  Since there are no connected clients, there is no reason to waste battery running
      vTaskSuspend(NULL);
    }
    //  Let other tasks run after serving every client
    taskYIELD();
    vTaskDelayUntil(&xLastWakeTime, xFrequency);
  }
}

const char JHEADER[] = "HTTP/1.1 200 OK\r\n" \
                       "Content-disposition: inline; filename=capture.jpg\r\n" \
                       "Content-type: image/jpeg\r\n\r\n";
const int jhdLen = strlen(JHEADER);

//設定jpg單張影像服務
void handleJPG(void)
{
  WiFiClient client = server.client();
  if (!client.connected()) return;
  client.write(JHEADER, jhdLen);
  client.write((char*)cam.getfb(), cam.getSize());
}

//使用者輸入錯誤網址時
void handleNotFound()
{
  String message = "Server is running!\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  server.send(200, "text / plain", message);
}

void setup()
{

  // Setup Serial connection:
  Serial.begin(115200);
  delay(1000); // wait for a second to let Serial connect
  // Configure the camera
  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; //FRAMESIZE_UXGA, SVGA, QVGA
  config.jpeg_quality = 12;//0-60
  config.fb_count = 2;

  if (cam.init(config) != ESP_OK) {
    Serial.println("Error initializing the camera");
    delay(10000);
    ESP.restart();
  }

  //  Configure and connect to WiFi
  IPAddress ip;

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(F("."));
  }
  ip = WiFi.localIP();
  Serial.println(F("WiFi connected"));
  Serial.println("");
  Serial.print("Stream Link: http://");
  Serial.print(ip);
  Serial.println("/stream");

  Serial.print("Still Jpg Link: http://");
  Serial.print(ip);
  Serial.println("/jpg");
  
  // Start mainstreaming RTOS task
  xTaskCreatePinnedToCore(
    mjpegCB,
    "mjpeg",
    4096,
    NULL,
    2,
    &tMjpeg,
    APP_CPU);
}

void loop() {
  //put your code here
}