ESP32-CAM Capture Fail: `camera_fb_t *fb = esp_camera_fb_get();`

Question

I am using the AI-Thinker ESP32-CAM for image capture, but I am unable to capture an image when I run my code with esp_camera_fb_get. Below is my code:

void sendImage()
{
    camera_fb_t *fb = esp_camera_fb_get();
    if (!fb)
    {
        Serial.println("Camera capture failed");
        return;
    }

    webSocket.sendBinary((const char *)fb->buf, fb->len);
    esp_camera_fb_return(fb);
}

My monitor window shows "Camera capture failed," but I have no idea what the issue might be.

I tried running the CameraWebServer example provided by ESP32-CAM, and it works correctly. However, when I switch to my own code, it fails to meet my requirements. Below is part of my code:

#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

#define LED_GPIO_NUM 4

class CameraSettings
{
public:
    int frameRate;
    int resolutionWidth;
    int resolutionHeight;

    CameraSettings()
        : frameRate(4), resolutionWidth(640), resolutionHeight(480) {}

    void applySettings()
    {
        if (psramFound())
        {
            sensor_t *s = esp_camera_sensor_get();
            if (resolutionWidth == 1280 && resolutionHeight == 720)
            {
                s->set_framesize(s, FRAMESIZE_HD);
            }
            else if (resolutionWidth == 640 && resolutionHeight == 480)
            {
                s->set_framesize(s, FRAMESIZE_VGA);
            }
            else if (resolutionWidth == 320 && resolutionHeight == 240)
            {
                s->set_framesize(s, FRAMESIZE_QVGA);
            }
            else
            {
                s->set_framesize(s, FRAMESIZE_VGA);
            }
        }
        else
        {
            Serial.println("PSRAM not found. Resolution adjustments are limited.");
        }

        Serial.println("Camera settings applied:");
        Serial.println("Frame Rate: " + String(frameRate));
        Serial.println("Resolution: " + String(resolutionWidth) + "x" + String(resolutionHeight));
    }

    void Initialize_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_sccb_sda = SIOD_GPIO_NUM;
        config.pin_sccb_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.fb_count = 1;

        esp_err_t err = esp_camera_init(&config);
        if (err != ESP_OK)
        {
            Serial.printf("Camera init failed with error 0x%x\n", err);
            return;
        }

        Serial.println("Camera setup completed");
    }
};

void loop()
{
    if (WiFi.status() != WL_CONNECTED)
    {
        reconnectWiFi();
    }

    if (!webSocket.available())
    {
        connectWebSocket();
    }

    if (isStreaming && isRegistered)
    {
        sendImage();
        delay(1000 / camera.frameRate);
    }

    webSocket.poll();
}

void sendImage()
{
    camera_fb_t *fb = esp_camera_fb_get();
    if (!fb)
    {
        Serial.println("Camera capture failed");
        return;
    }

    webSocket.sendBinary((const char *)fb->buf, fb->len);
    esp_camera_fb_return(fb);
}

If you have any repair experience or similar situations, please share with me, I will be very grateful!