# 深度与视频同步

本示例演示了如何使用 DepthAI Sync 节点来同步 StereoDepth 和 Color Camera 节点的输出。它展示了如何实时处理和显示来自立体相机的视差图以及来自彩色相机的视频帧。

### 类似示例

 * [IMU 与视频同步](https://docs.luxonis.com/software-v3/depthai/examples/imu_video_sync.md)
 * [多脚本同步](https://docs.luxonis.com/software-v3/depthai/examples/scripts_sync.md)

## 演示

这个示例需要DepthAI v3 API，参见[安装说明](https://docs.luxonis.com/software-v3/depthai.md)。

## 源代码

#### Python

```python
import depthai as dai
import numpy as np
import cv2
from datetime import timedelta

pipeline = dai.Pipeline()

monoLeft = pipeline.create(dai.node.MonoCamera)
monoRight = pipeline.create(dai.node.MonoCamera)
color = pipeline.create(dai.node.ColorCamera)
stereo = pipeline.create(dai.node.StereoDepth)
sync = pipeline.create(dai.node.Sync)

xoutGrp = pipeline.create(dai.node.XLinkOut)

xoutGrp.setStreamName("xout")

monoLeft.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
monoLeft.setCamera("left")
monoRight.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
monoRight.setCamera("right")

stereo.setDefaultProfilePreset(dai.node.StereoDepth.PresetMode.HIGH_ACCURACY)

color.setCamera("color")

sync.setSyncThreshold(timedelta(milliseconds=50))

monoLeft.out.link(stereo.left)
monoRight.out.link(stereo.right)

stereo.disparity.link(sync.inputs["disparity"])
color.video.link(sync.inputs["video"])

sync.out.link(xoutGrp.input)

disparityMultiplier = 255.0 / stereo.initialConfig.getMaxDisparity()
with dai.Device(pipeline) as device:
    queue = device.getOutputQueue("xout", 10, False)
    while True:
        msgGrp = queue.get()
        for name, msg in msgGrp:
            frame = msg.getCvFrame()
            if name == "disparity":
                frame = (frame * disparityMultiplier).astype(np.uint8)
                frame = cv2.applyColorMap(frame, cv2.COLORMAP_JET)
            cv2.imshow(name, frame)
        if cv2.waitKey(1) == ord("q"):
            break
```

#### C++

```cpp
#include <iostream>

// Includes common necessary includes for development using depthai library
#include "depthai/depthai.hpp"

int main() {
    // Create pipeline
    dai::Pipeline pipeline;

    // Define sources and outputs
    auto monoLeft = pipeline.create<dai::node::MonoCamera>();
    auto monoRight = pipeline.create<dai::node::MonoCamera>();
    auto color = pipeline.create<dai::node::ColorCamera>();
    auto stereo = pipeline.create<dai::node::StereoDepth>();
    auto sync = pipeline.create<dai::node::Sync>();

    auto xoutGrp = pipeline.create<dai::node::XLinkOut>();

    // XLinkOut
    xoutGrp->setStreamName("xout");

    // Properties
    monoLeft->setResolution(dai::MonoCameraProperties::SensorResolution::THE_400_P);
    monoLeft->setCamera("left");
    monoRight->setResolution(dai::MonoCameraProperties::SensorResolution::THE_400_P);
    monoRight->setCamera("right");

    stereo->setDefaultProfilePreset(dai::node::StereoDepth::PresetMode::HIGH_ACCURACY);

    color->setCamera("color");

    sync->setSyncThreshold(std::chrono::milliseconds(100));

    // Linking
    monoLeft->out.link(stereo->left);
    monoRight->out.link(stereo->right);

    stereo->disparity.link(sync->inputs["disparity"]);
    color->video.link(sync->inputs["video"]);

    sync->out.link(xoutGrp->input);

    // Connect to device and start pipeline
    dai::Device device(pipeline);

    auto queue = device.getOutputQueue("xout", 10, true);

    float disparityMultiplier = 255 / stereo->initialConfig.getMaxDisparity();

    while(true) {
        auto msgGrp = queue->get<dai::MessageGroup>();
        for(auto& frm : *msgGrp) {
            auto imgFrm = std::dynamic_pointer_cast<dai::ImgFrame>(frm.second);
            cv::Mat img = imgFrm->getCvFrame();
            if(frm.first == "disparity") {
                img.convertTo(img, CV_8UC1, disparityMultiplier);  // Extend disparity range
                cv::applyColorMap(img, img, cv::COLORMAP_JET);
            }
            cv::imshow(frm.first, img);
        }

        int key = cv::waitKey(1);
        if(key == 'q' || key == 'Q') {
            return 0;
        }
    }
    return 0;
}
```

### 工作原理

 * 初始化左右摄像头的 MonoCamera 节点。
 * 设置 ColorCamera 节点。
 * 创建 StereoDepth 节点以进行深度感知。
 * 配置 Sync 节点以同步来自 StereoDepth 节点的视差图和来自 ColorCamera 节点的视频帧。
 * 使用 OpenCV 显示同步后的帧。帧的同步阈值设为 50 毫秒。

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