【工作笔记004】camera本地预览并获取YUV数据

1.camer调用需要在AndroidManifest.xml中添加申请相机权限

<uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />

一、预览activity代码

package com.bw.test;

import android.annotation.TargetApi;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.io.IOException;
import java.util.List;

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback, Camera.PreviewCallback {

    private SurfaceView surfaceView;
    private Camera.Parameters parameters;
    private int formatType;
    private int width=1920;
    private int height=1080;
    private int framerate=24;
    private SurfaceHolder surfaceHolder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        surfaceView = findViewById(R.id.surfaceView);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        Camera camera = getBackCamera();
        startcamera(camera);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }

    private void startcamera(Camera mCamera){
        if(mCamera != null){
            try {
                mCamera.setPreviewCallback(this);

                //mCamera.setDisplayOrientation(90);
                if(parameters == null){
                    parameters = mCamera.getParameters();
                }

                getPreviewFormats(parameters);
                parameters.setPreviewFormat(formatType);//设置输出的YUV数据格式
                parameters.setPreviewSize(width, height);//设置预览画面分辨率，需要相机支持
                parameters.setPreviewFpsRange(framerate*1000,framerate*1000);//设置的帧率需要相机支持，否则会报错

                parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);//设置自动聚焦

                mCamera.setParameters(parameters);
                mCamera.setPreviewDisplay(surfaceHolder);//设置相机画面预览渲染窗口
                mCamera.startPreview();
                
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    /**
     * 获取设备支持的预览帧画面格式
     * @param parameters
     */
    private void getPreviewFormats(Camera.Parameters parameters) {
        List<Integer> previewFormatsSizes = parameters.getSupportedPreviewFormats();
        if( -1 != previewFormatsSizes.indexOf(ImageFormat.YV12))
        {
            formatType = ImageFormat.YV12;
        }
        else if(-1 != previewFormatsSizes.indexOf(ImageFormat.NV21))
        {
            formatType = ImageFormat.NV21;
        }
        else
        {
            formatType = -1;
            return ;
        }
    }

    @TargetApi(9)
    private Camera getBackCamera() {
        Camera c = null;
        try {
            c = Camera.open(0); // attempt to get a Camera instance
        } catch (Exception e) {
            e.printStackTrace();
        }
        return c; // returns null if camera is unavailable
    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        //TODO data就为YUV数据
    }
}

获取到相机回调的YUV数据后就可以对其进行编码操作。