3.4.2 JDK 示例参考

1.基础示例

1.1 JDK 数据帧格式

JdkFrame 是各模块之间传递图像的统一数据结构:

class JdkFrame {
public:
    JdkFrame(int dma_fd_, size_t size_, int w, int h);
    ~JdkFrame();

    // 拷贝 DMA 缓冲区数据到主机内存并返回指针
    unsigned char* toHost() const;

    // 克隆数据至 vector
    std::vector<unsigned char> Clone() const;

    // 手动释放映射（如有必要）
    // 保存为 YUV NV12 格式文件
    bool saveToFile(const std::string& filename) const;
    bool loadFromFile(const std::string& filename, size_t expected_size);

    int getDMAFd() const;
    size_t getSize() const { return size_; }
    int getWidth() const { return width_; }
    int getHeight() const { return height_; }

    int MemCopy(const uint8_t* nalu, int nalu_size, int offset = 0);

private:
    size_t size_;   // 数据总大小，NV12格式宽高相关
    int width_;
    int height_;
    JdkDma dma_;
    std::shared_ptr<JdkDmaBuffer> data;
};

1.2 MIPI 摄像头采集

// 打开摄像节点
auto camera = JdkCamera::create("/device/video50", 1920, 1080, V4L2_PIX_FMT_NV12); 

// 获取一帧数据
auto frame = camera->getFrame(); 

1.3 编码（JdkEncoder）

// 创建编码器
auto encoder = std::make_shared<JdkEncoder>(width, height, CODING_H264, PIXEL_FORMAT_NV12);

// 对单帧数据进行编码
auto encodedFrame = encoder->Encode(jdkFrame);

1.4 解码（JdkDecoder）

// 创建解码器
auto decoder = std::make_shared<JdkDecoder>(width, height, CODING_H264, PIXEL_FORMAT_NV12);

// 对单帧数据进行解码
auto decodedFrame = decoder->Decode(jdkFrame);

1.5 图像处理（JdkV2D）

// 创建 V2D 模块实例
auto v2d = std::make_shared<JdkV2D>();

// NV12 转换为 RGB8888 格式
auto rgba_frame = v2d->convert_format(input_nv12, V2D_FMT_RGB888);

// 绘制单个矩形框
v2d->draw_rect(input_nv12, box, 0xFFFFFF00, 4); // 黄色，线宽4

// 绘制多个矩形框
v2d->draw_rects(input_nv12, {{30, 20, 100, 80}, {60, 40, 200, 160}}, 0x00ffcc66, 4); // 线宽4

// 对帧数据缩放
auto resized_frame = v2d->resize(jdkFrame, 1920, 1080);

// 同时缩放并格式转换
auto converted_frame = v2d->resize_and_convert(jdkFrame, 1920, 1080, V2D_FMT_RGB888);

1.6 SDL 显示（JdkVo）

// 创建视频输出（VO）对象
auto jdkvo = std::make_shared<JdkVo>(width, height, PIXEL_FORMAT_NV12);

// 显示一帧图像
auto ret = jdkvo->sendFrame(jdkFrame);

1.7 DRM 显示（JdkDrm）

// 创建 DRM 对象
auto drm = std::make_shared<JdkDrm>(width, height, width, PixelFmt::NV12, "/dev/dri/card1");

// 显示一帧图像
auto ret = drm->sendFrame(jdkFrame1);

1.8 AI 推理（YOLOv8）

// 创建算法推理引擎实例
auto engine = YOLOV8Det::create_infer("yolov8n.q.onnx", "onnx");

// 对帧数据进行推理
auto result = engine->commit(jdkFrame).get();

// 绘制推理结果
draw_nv12(jdkFrame, std::any_cast<YOLOV8Det::Objects>(result));

2.综合示例

2.1 JDK SDK 下载与安装

wget https://archive.spacemit.com/ros2/code/jdk_sdk.tar.gz
sudo tar xvf jdk_sdk.tar.gz

目录结构如下：

jdk_sdk
├── include
│   ├── data_type.hpp
│   ├── IConver.hpp
│   ├── IEngine.hpp
│   ├── IPlugin.hpp
│   ├── ITensor.hpp
│   ├── JdkCamera.hpp
│   ├── JdkDecoder.hpp
│   ├── JdkDma.hpp
│   ├── JdkDrm.hpp
│   ├── JdkEncoder.hpp
│   ├── JdkFrame.hpp
│   ├── jdk_log.h
│   ├── JdkUsbCam.hpp
│   ├── jdkV2d.hpp
│   ├── JdkVo.hpp
│   ├── json.hpp
│   └── Tensor.hpp
├── jdk_examples
│   ├── jdk_cam
│   ├── jdk_client
│   ├── jdk_drm
│   ├── jdk_frame
│   ├── jdk_infer
│   ├── jdk_infer@rtsp
│   ├── jdk_server
│   ├── jdk_usbcam
│   ├── jdk_v2d
│   ├── jdk_vdec
│   ├── jdk_venc
│   └── jdk_vo
├── ko
│   └── jdk_dma.ko
├── lib
│   ├── libengine.so
│   ├── libjdk_cam.so
│   ├── libjdk_dma.so
│   ├── libjdk_drm.so
│   ├── libjdk_frame.so
│   ├── libjdk_usbcam.so
│   ├── libjdk_v2d.so
│   ├── libjdk_vdec.so
│   ├── libjdk_venc.so
│   ├── libjdk_vo.so
│   ├── libnet_client.so
│   └── libnet_server.so
├── Makefile
└── README.md

2.2 示例说明

jdk_examples
├── jdk_cam       # 摄像头模块
├── jdk_client    # 客户端模块
├── jdk_drm       # DRM 相关模块
├── jdk_frame     # 帧处理模块
├── jdk_infer     # 推理模块
├── jdk_infer@rtsp# 视频采集RTSP输出和并行推理
├── jdk_server    # 服务端模块
├── jdk_v2d       # 视频二维模块
├── jdk_vdec      # 视频解码模块
├── jdk_venc      # 视频编码模块
└── jdk_vo        # 视频输出模块

2.3编译示例程序

进入摄像头模块目录并编译示例：

cd jdk_sdk
make all

示例编译输出：

make -C jdk_examples/jdk_cam all
make[1]: Entering directory '/home/work/jdk_sdk/jdk_examples/jdk_cam'
Compile depends C++ src/main.cpp
Compile CXX src/main.cpp
Link workspace/jdk_cam

2.3 运行示例

在运行 jdk 示例前，需要先安装 jdk dma 驱动。

insmod ./ko/jdk_dma.ko
cd jdk_examples/jdk_usbcam
./workspace/jdk_usbcam /dev/video20

🚨 提示：请根据实际情况确认设备节点路径，如 /dev/video20。可通过 v4l2-ctl --list-devices 命令查看设备信息。

运行后终端将输出模块初始化与图像采集的日志信息。

2.4 启动日志示例

VIDIOC_STREAMON succeeded
[MPP-DEBUG] 10800:module_init:159 +++++++++++++++ module init, module type = 9
[MPP-DEBUG] 10800:find_v4l2_linlonv5v7_plugin:83 yeah! we have v4l2_linlonv5v7_codec plugin---------------
[MPP-DEBUG] 10800:module_init:199 ++++++++++ V4L2_LINLONV5V7 (/usr/lib/libv4l2_linlonv5v7_codec.so)
[MPP-DEBUG] 10800:module_init:199 ++++++++++ open (/usr/lib/libv4l2_linlonv5v7_codec.so) success !
[MPP-DEBUG] 10800:al_dec_create:337 init create
[MPP-DEBUG] 10800:al_dec_init:398 input para check: foramt:0x4745504a output format:0x3231564e input buffer num:12 output buffer num:8
[MPP-DEBUG] 10800:al_dec_init:421 video fd = 4, device path = '/dev/video0'
[MPP-DEBUG] 10800:createCodec:115 create a codec, width=1280 height=720 align=1 inputtype=2 outputtype=9 inputformat=4745504a outputformat=3231564e inputbufnum=12 outputbufnum=8
[MPP-DEBUG] 10800:createPort:80 create a port, type=2 format_fourcc=1195724874
[MPP-DEBUG] 10800:createPort:80 create a port, type=9 format_fourcc=842094158
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=4745504a
[MPP-DEBUG] 10800:printFormat:294 PRINTFORMAT ===== type: 2, format: 1195724874, width: 1280, height: 720, bytesperline: 0, sizeimage: 1048576
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=3231564e
[MPP-DEBUG] 10800:printFormat:283 PRINTFORMAT ===== type: 9, format: 842094158, width: 1280, height: 720, nplanes: 2, bytesperline: [1280 1280 0], sizeimage: [921600 460800 0]
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:2 count:12(12) memory:1
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:8(8) memory:4
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956058513
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956058513
[MPP-DEBUG] 10800:al_dec_init:449 init finish
[MPP-DEBUG] 10800:VO_CreateChannel:43 create VO Channel success!
[MPP-DEBUG] 10800:module_init:159 +++++++++++++++ module init, module type = 101
[MPP-DEBUG] 10800:check_vo_sdl2:121 yeah! have vo_sdl2---------------
[MPP-DEBUG] 10800:find_vo_sdl2_plugin:86 yeah! we have vo_sdl2_plugin plugin---------------
[MPP-DEBUG] 10800:module_init:207 ++++++++++ VO_SDL2 (/usr/lib/libvo_sdl2_plugin.so)
[MPP-DEBUG] 10800:module_init:207 ++++++++++ open (/usr/lib/libvo_sdl2_plugin.so) success !
[MPP-ERROR] 10800:al_vo_init:93 SDL could not initialize! SDL_Error: wayland not available
[MPP-ERROR] 10800:al_vo_init:128 k1 vo_sdl2 init fail
[MPP-DEBUG] 10800:VO_Init:66 init VO Channel, ret = -400
[MPP-ERROR] 10800:JdkVo:32 VO_init failed, please check!
[MPP-INFO] 10801:runpoll:321 Now k1 hardware decoding ...
select: Resource temporarily unavailable
Failed to capture frame 0
NO data, return.
[MPP-DEBUG] 10801:handleEvent:453 get V4L2_EVENT_SOURCE_CHANGE event, do notify!
[MPP-DEBUG] 10800:handleOutputBuffer:1509 Resolution changed:0 new size: 1280 x 720
[MPP-DEBUG] 10800:streamoff:571 Stream off 1751956060839
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:0(0) memory:4
[MPP-DEBUG] 10800:getTrySetFormat:196 width=1280 height=720 align=1 pixel_format=3231564e
[MPP-DEBUG] 10800:printFormat:283 PRINTFORMAT ===== type: 9, format: 842094158, width: 1280, height: 720, nplanes: 2, bytesperline: [1280 1280 0], sizeimage: [921600 460800 0]
[MPP-DEBUG] 10800:allocateBuffers:340 Request buffers. type:9 count:12(12) memory:4
[MPP-DEBUG] 10800:streamon:558 Stream on 1751956060850
[MPP-ERROR] 10800:queueBuffer:461 Failed to queue buffer. type = 9 (Invalid argument)
[MPP-ERROR] 10800:al_dec_return_output_frame:652 queueBuffer failed, this should not happen, please check!
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:1,dma_fd:33 width:1280,height:720,size:1382400
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:2,dma_fd:33 width:1280,height:720,size:1382400
[MPP-DEBUG] 10800:VO_Process:82 vo one packet, ret = 0
index:3,dma_fd:33 width:1280,height:720,size:1382400

2.5 示例 1：USB 摄像头 → 解码 → 显示

// 打开摄像头节点
auto camera = JdkUsbCam::create(device, width, height, V4L2_PIX_FMT_MJPEG);
// 创建 JPEG 解码器
auto decoder = std::make_shared<JdkDecoder>(width, height, CODING_MJPEG, PIXEL_FORMAT_NV12);
// 初始化显示模块（vo）
auto jdkvo = std::make_shared<JdkVo>(width, height, PIXEL_FORMAT_NV12);
// 获取一帧图像数据
auto frame = camera->getFrame();
// 解码 JPEG 图像
auto decFrame = decoder->Decode(frame)
// 将图像帧发送至显示模块
auto ret = jdkvo->sendFrame(decFrame);

2.6 示例 2：MIPI 摄像头采集 → 实时显示

// 打开摄像头节点
auto camera = JdkCamera::create("/device/video50", 1920, 1080, V4L2_PIX_FMT_NV12);
// 初始化显示模块（vo）
auto jdkvo = std::make_shared<JdkVo>(1920, 1080, PIXEL_FORMAT_NV12);
// 获取一帧图像数据
auto frame = camera->getFrame();
// 将图像帧发送至显示模块
auto ret = jdkvo->sendFrame(frame);

2.7 示例 3：MIPI 摄像头 → 编码 → RTSP 推流

// 创建摄像头采集对象
auto camera = JdkCamera::create("/dev/video50", width, height, V4L2_PIX_FMT_NV12);

// 创建编码器对象
auto encoder = std::make_shared<JdkEncoder>(width, height, CODING_H264, PIXEL_FORMAT_NV12);

// 创建 RTSP 服务器
auto rtsp_ = std::make_shared<RTSPServer>("test", 1, 8554, VideoCodecType::H264);

while (running) {
    auto frame = camera->getFrame(); // 获取一帧图像
    if (!frame) {
        std::cerr << "Failed to capture frame\n";
        continue;
    }
    auto encFrame = encoder->Encode(frame); // 编码
    if (encFrame) {
        size_t sz = encFrame->getSize();
        uint8_t* data = (uint8_t*)encFrame->toHost();
        rtsp_->send_nalu(data, sz, getTimestamp()); // 推送编码数据
    }
}

2.8 示例 4：RTSP → 解码 → DRM 显示

// 创建 RTSP 客户端
auto netclient = std::make_shared<NetClient>(device_id, channel_id, 0, "");

// 创建 JDK 解码器
auto decoder = std::make_shared<JdkDecoder>(width, height, CODING_H264, PIXEL_FORMAT_NV12);

// 启动接收码流
netclient->start("rtsp://admin:123456@169.254.202.148:8554/stream_8554");

// 绑定视频回调函数
video_cb_ = std::bind(&NetClient::rtsp_video_cb, this,
                      std::placeholders::_1, std::placeholders::_2,
                      std::placeholders::_3, std::placeholders::_4,
                      std::placeholders::_5);

// 视频回调函数实现
int NetClient::rtsp_video_cb(LPBYTE pdata, int len, unsigned int ts,
                             unsigned short seq, void* puser) {
    if (!decoder_) {
        // 初始化解码器及 DRM 显示模块
        decoder_ = std::make_shared<JdkDecoder>(info_tmp->video.width,
                                                info_tmp->video.height,
                                                CODING_H264, PIXEL_FORMAT_NV12);

        drm_ = std::make_shared<JdkDrm>(info_tmp->video.width,
                                        info_tmp->video.height,
                                        info_tmp->video.width,
                                        PixelFmt::NV12, "/dev/dri/card1");

        drmframe = std::make_shared<JdkFrame>(-1,
                                              info_tmp->video.width * info_tmp->video.height * 3 / 2,
                                              info_tmp->video.width,
                                              info_tmp->video.height);
    } else {
        frame = decoder_->Decode(pdata, len);         // 解码
        drmframe->MemCopy(frame->toHost(), frame->getSize()); // 拷贝数据到显示缓冲区
        drm_->sendFrame(drmframe);                     // 显示图像
    }
}

2.9 示例 5：MIPI 摄像头 → YOLOv8 推理 → 画框 → 显示

// 创建摄像头采集对象
auto camera = JdkCamera::create("/dev/video50", width, height, V4L2_PIX_FMT_NV12);
// 初始化显示模块（vo）
auto jdkvo = std::make_shared<JdkVo>(width, height, PIXEL_FORMAT_NV12);
// 创建算法推理引擎实例
auto engine = YOLOV8Det::create_infer("yolov8n.q.onnx", "onnx");
//初始化 v2d模块
auto v2d = std::make_shared<JdkV2D>();
// 获取一帧图像数据
auto jdkFrame = camera->getFrame();
// 对帧数据进行推理
auto result = engine->commit(jdkFrame).get();
//通过v2d模块进行叠框
draw_nv12(jdkFrame, std::any_cast<YOLOV8Det::Objects>(result));
int draw_nv12(std::shared_ptr<JdkFrame> frame, YOLOV8Det::Objects box_result)
{
    // printf(" box_result.size:%d\r\n", box_result.size());
    auto v2d = std::make_shared<JdkV2D>();
    auto reult = v2d->resize(frame, 320, 320);
    reult->saveToFile("320x320_resize.nv12");
    auto boxs = box_result[0].boxs;
    for (int i = 0; i < boxs.size(); ++i)
    {
        auto &ibox = boxs[i];
        float left = ibox.rect.tl().x;
        float top = ibox.rect.tl().y;
        float right = ibox.rect.br().x;
        float bottom = ibox.rect.br().y;
        int class_label = ibox.label;
        float confidence = ibox.prob;
        v2d->draw_rect(reult, {ibox.rect.x, ibox.rect.y, ibox.rect.width, ibox.rect.height}, 0xFFFF00, 2);
    }
    // mkdir(save_dir);
    // auto save_file = save_dir + "/" + file;
    // cv::imwrite(save_file.data(), image);
    // reult->saveToFile("320x320_OSD_result.nv12");
    return 0;
}
// 将图像帧发送至显示模块进行显示
auto ret = jdkvo->sendFrame(jdkFrame);

2.10 示例 6：MIPI 摄像头 → YOLOv8 推理 + RTSP 实时编码推流(并行输出)

std::atomic<bool>					  running(true);
safe_queue<std::shared_ptr<JdkFrame>> queue;

void input_thread() {
	std::string wait;
	std::getline(std::cin, wait);
	running = false;
}

void infer_thread() {
	auto Engin = YOLOV8Det::create_infer("yolov8n.q.onnx", "onnx");
	if (nullptr == Engin) {
		printf("create_infer error!!!!\r\n");
		return;
	}

	while (running) {
		auto frame = queue.get(&running);
		if (!frame) {
			printf("Warning: frame is NULL!\n");
			continue;
		}
		auto result = Engin->commit(frame).get();
	}
}

static uint32_t getTimestamp() {
	struct timeval tv = {0};
	gettimeofday(&tv, NULL);
	uint32_t ts = ((tv.tv_sec * 1000) + ((tv.tv_usec + 500) / 1000)) * 90;	// clockRate/1000;
	return ts;
}

int main(int argc, char *argv[]) {
	int	 width	= 1920;
	int	 height = 1080;
	auto camera = JdkCamera::create("/dev/video50", width, height, V4L2_PIX_FMT_NV12);
	if (!camera) {
		std::cerr << "Failed to create camera\n";
		return -1;
	}
	auto encoder = std::make_shared<JdkEncoder>(width, height, CODING_H264, PIXEL_FORMAT_NV12);
	auto rtsp_	 = std::make_shared<RTSPServer>("test", 1, 8554, VideoCodecType::H264);

	std::thread th(input_thread);
	std::thread th_infer(infer_thread);

	while (running) {
		auto frame = camera->getFrame();
		if (!frame) {
			std::cerr << "Failed to capture frame " << "\n";
			continue;
		}
		queue.push(frame, &running);
		if (auto encFrame = encoder->Encode(frame); encFrame) {
			size_t	 sz	  = encFrame->getSize();
			uint8_t *data = (uint8_t *)encFrame->toHost();
			rtsp_->send_nalu(data, sz, getTimestamp());
		}
		static int i = 0;
		if ((i % 5000) == 0) {
			printf("dma_fd:%d width:%d,height:%d,size:%d\r\n", frame->getDMAFd(), frame->getWidth(), frame->getHeight(), frame->getSize());
		}
	}

	if (th.joinable())
		th.join();
	if (th_infer.joinable())
		th_infer.join();
	std::cout << "✅ Exited by user input." << std::endl;

	return 0;
}

3.常见问题与建议

问题	说明
检测不到摄像头	检查 USB 接口连接、尝试其他端口、确认摄像头型号
摄像头打不开	可能摄像头未被识别，或驱动不支持
SDL 报错	系统图形库依赖缺失，不影响摄像头采集功能
图像不显示	检查 vo 初始化日志、确认使用的显示通道和权限

1.基础示例​

1.1 JDK 数据帧格式​

1.2 MIPI 摄像头采集​

1.3 编码（JdkEncoder）​

1.4 解码（JdkDecoder）​

1.5 图像处理（JdkV2D）​

1.6 SDL 显示（JdkVo）​

1.7 DRM 显示（JdkDrm）​

1.8 AI 推理（YOLOv8）​

2.综合示例​

2.1 JDK SDK 下载与安装​

2.2 示例说明​

2.3编译示例程序​

2.3 运行示例​

2.4 启动日志示例​

2.5 示例 1：USB 摄像头 → 解码 → 显示​

2.6 示例 2：MIPI 摄像头采集 → 实时显示​

2.7 示例 3：MIPI 摄像头 → 编码 → RTSP 推流​

2.8 示例 4：RTSP → 解码 → DRM 显示​

2.9 示例 5：MIPI 摄像头 → YOLOv8 推理 → 画框 → 显示​

2.10 示例 6：MIPI 摄像头 → YOLOv8 推理 + RTSP 实时编码推流(并行输出)​

3.常见问题与建议​

1.基础示例

1.1 JDK 数据帧格式

1.2 MIPI 摄像头采集

1.3 编码（JdkEncoder）

1.4 解码（JdkDecoder）

1.5 图像处理（JdkV2D）

1.6 SDL 显示（JdkVo）

1.7 DRM 显示（JdkDrm）

1.8 AI 推理（YOLOv8）

2.综合示例

2.1 JDK SDK 下载与安装

2.2 示例说明

2.3编译示例程序

2.3 运行示例

2.4 启动日志示例

2.5 示例 1：USB 摄像头 → 解码 → 显示

2.6 示例 2：MIPI 摄像头采集 → 实时显示

2.7 示例 3：MIPI 摄像头 → 编码 → RTSP 推流

2.8 示例 4：RTSP → 解码 → DRM 显示

2.9 示例 5：MIPI 摄像头 → YOLOv8 推理 → 画框 → 显示

2.10 示例 6：MIPI 摄像头 → YOLOv8 推理 + RTSP 实时编码推流(并行输出)

3.常见问题与建议