【鸿蒙性能优化】基于Camera Kit，获取相机流数据传递给native，进行压缩编码

示例场景：ATS侧启动相机，使用摄像头采集视频流数据，获取相机视频流数据传递到native侧，通过buffer模式将视频编码成MP4文件保存到沙箱路径。

方案描述：具体实现步骤可分为：

Step1：申请权限，启动相机。

Step2: 启动录制，获取视频流数据，获取一帧图像转成JPG格式保存到沙箱路径。

Step3: 视频流数据传递到native侧，进行压缩编码，生成文件保存。

步骤一: 申请权限，启动相机。需要相机、麦克风、媒体位置、写入媒体和读取媒体权限。

"requestPermissions": [

{

"name": "ohos.permission.CAMERA",

"reason": "$string:app_name",

"usedScene": {

"abilities": [

"FormAbility"

],

"when": "always"

}

},

{

"name": "ohos.permission.MICROPHONE",

"reason": "$string:app_name",

"usedScene": {

"abilities": [

"FormAbility"

],

"when": "always"

}

},

{

"name": "ohos.permission.MEDIA_LOCATION",

"reason": "$string:app_name",

"usedScene": {

"abilities": [

"FormAbility"

],

"when": "always"

}

},

{

"name": "ohos.permission.WRITE_MEDIA",

"reason": "$string:app_name",

"usedScene": {

"abilities": [

"FormAbility"

],

"when": "always"

}

},

{

"name": "ohos.permission.READ_MEDIA",

"reason": "$string:app_name",

"usedScene": {

"abilities": [

"FormAbility"

],

"when": "always"

}

}

]

2：启动相机，预览实现。导入camera接口，创建双路预览流通道，使用XComponent组件和ImageReceiver组件创建Surface用来显示和获取预览图像。

async function createDualChannelPreview(cameraManager: camera.CameraManager, XComponentSurfaceId: string, receiver: image.ImageReceiver): Promise<void> {

// 获取支持的相机设备对象

let camerasDevices: Array<camera.CameraDevice> = cameraManager.getSupportedCameras();

// 获取支持的模式类型

let sceneModes: Array<camera.SceneMode> = cameraManager.getSupportedSceneModes(camerasDevices[0]);

let isSupportPhotoMode: boolean = sceneModes.indexOf(camera.SceneMode.NORMAL_PHOTO) >= 0;

if (!isSupportPhotoMode) {

console.error('photo mode not support');

return;

}

// 获取profile对象

let profiles: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(camerasDevices[0], camera.SceneMode.NORMAL_PHOTO); // 获取对应相机设备profiles

let previewProfiles: Array<camera.Profile> = profiles.previewProfiles;

// 预览流1

let previewProfilesObj: camera.Profile = previewProfiles[0];

// 预览流2

let previewProfilesObj2: camera.Profile = previewProfiles[0];

// 创建 预览流1 输出对象

let previewOutput: camera.PreviewOutput = cameraManager.createPreviewOutput(previewProfilesObj, XComponentSurfaceId);

// 创建 预览流2 输出对象

let imageReceiverSurfaceId: string = await receiver.getReceivingSurfaceId();

let previewOutput2: camera.PreviewOutput = cameraManager.createPreviewOutput(previewProfilesObj2, imageReceiverSurfaceId);

// 创建cameraInput对象

let cameraInput: camera.CameraInput = cameraManager.createCameraInput(camerasDevices[0]);

// 打开相机

await cameraInput.open();

// 会话流程

let photoSession: camera.CaptureSession = cameraManager.createCaptureSession();

// 开始配置会话

photoSession.beginConfig();

// 把CameraInput加入到会话

photoSession.addInput(cameraInput);

// 把 预览流1 加入到会话

photoSession.addOutput(previewOutput);

// 把 预览流2 加入到会话

photoSession.addOutput(previewOutput2);

// 提交配置信息

await photoSession.commitConfig();

// 会话开始

await photoSession.start();

}

## **步骤二**：启动录制，获取相机视频流数据。

1：生成相机视频流数据：视频流数据是通过在onPageShow里面启动本地录制生成，当页面显示时，会调用 startRecord()方法开始录制，在页面隐藏时，调用 stopRecorder()函数停止录制视频，并释放相机资源。


async onPageShow() {

this.startRecord();

await grantPermission().then(res => {

console.info(TAG, `权限申请成功 ${JSON.stringify(res)}`);

if (res) {

createDualChannelPreview(this.surfaceId, this.receiver);

}

})

}

private startRecord() {

videoCompressor.startRecorder(getContext(), cameraWidth, cameraHeight)

.then((data) => {

if (data.code == CompressorResponseCode.SUCCESS) {

Logger.debug("videoCompressor-- record success");

} else {

Logger.debug("videoCompressor code:" + data.code + "--error message:" + data.message);

}

}).catch((err: Error) => {

Logge