1 概述
通过Android Camera拍摄预览中设置setPreviewCallback实现onPreviewFrame接口,实时截取每一帧视频流数据
2 知识点
① Android Camera使用: 参考 Refs/Related 0-4
Camera 支持格式
拍照流程
② Android SurfaceView使用: 参考 Refs/Related 5-10
③ Camera权限
3 核心源码
① SurfaceView相关
// 定义对象
private SurfaceView mSurfaceview = null; // SurfaceView对象:(视图组件)视频显示
private SurfaceHolder mSurfaceHolder = null; // SurfaceHolder对象:(抽象接口)SurfaceView支持类
private Camera mCamera =null; // Camera对象,相机预览
// InitSurfaceView
private void initSurfaceView()
{
mSurfaceview = (SurfaceView)
this.findViewById(R.id.Surfaceview);
mSurfaceHolder = mSurfaceview.getHolder();
// 绑定SurfaceView,取得SurfaceHolder对象
mSurfaceHolder.addCallback(mainActivity.
this);
// SurfaceHolder加入回调接口
// mSurfaceHolder.setFixedSize(176, 144); // 预览大小設置
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
// 設置顯示器類型,setType必须设置
}
② 主Activity实现SurfaceHolder.Callback接口,编写回调函数
/*【SurfaceHolder.Callback 回调函数】*/ public void surfaceCreated(SurfaceHolder holder)
// SurfaceView启动时/初次实例化,预览界面被创建时,该方法被调用。
{
// TODO Auto-generated method stub
mCamera = Camera.open();
// 开启摄像头(2.3版本后支持多摄像头,需传入参数)
try {
Log.i(TAG, "SurfaceHolder.Callback:surface Created");
mCamera.setPreviewDisplay(mSurfaceHolder);
//set the surface to be used for live preview
}
catch (Exception ex)
{
if(
null != mCamera)
{
mCamera.release();
mCamera =
null;
}
Log.i(TAG+"initCamera", ex.getMessage());
}
}
public void surfaceChanged(SurfaceHolder holder,
int format,
int width,
int height)
// 当SurfaceView/预览界面的格式和大小发生改变时,该方法被调用
{
// TODO Auto-generated method stub
Log.i(TAG, "SurfaceHolder.Callback:Surface Changed");
//mPreviewHeight = height;
//mPreviewWidth = width;
initCamera();
}
public void surfaceDestroyed(SurfaceHolder holder)
// SurfaceView销毁时,该方法被调用
{
// TODO Auto-generated method stub
Log.i(TAG, "SurfaceHolder.Callback:Surface Destroyed");
if(
null != mCamera)
{
mCamera.setPreviewCallback(
null);
//!!这个必须在前,不然退出出错
mCamera.stopPreview();
bIfPreview =
false;
mCamera.release();
mCamera =
null;
}
}
核心子函数: 相机预览
1 /*【2】【相机预览】*/
2 private void initCamera()
//surfaceChanged中调用
3 {
4 Log.i(TAG, "going into initCamera");
5 if (bIfPreview)
6 {
7 mCamera.stopPreview();
//stopCamera();
8 }
9 if(
null != mCamera)
10 {
11 try
12 {
13 /* Camera Service settings*/
14 Camera.Parameters parameters = mCamera.getParameters();
15 // parameters.setFlashMode("off"); // 无闪光灯
16 parameters.setPictureFormat(PixelFormat.JPEG);
//Sets the image format for picture 设定相片格式为JPEG,默认为NV21
17 parameters.setPreviewFormat(PixelFormat.YCbCr_420_SP);
//Sets the image format for preview picture,默认为NV21
18 /*【ImageFormat】JPEG/NV16(YCrCb format,used for Video)/NV21(YCrCb format,used for Image)/RGB_565/YUY2/YU12*/
19
20 // 【调试】获取caera支持的PictrueSize,看看能否设置??
21 List
pictureSizes = mCamera.getParameters().getSupportedPictureSizes();
22 List previewSizes = mCamera.getParameters().getSupportedPreviewSizes();
23 List previewFormats = mCamera.getParameters().getSupportedPreviewFormats();
24 List previewFrameRates = mCamera.getParameters().getSupportedPreviewFrameRates();
25 Log.i(TAG+"initCamera", "cyy support parameters is ");
26 Size psize = null;
27 for (int i = 0; i < pictureSizes.size(); i++)
28 {
29 psize = pictureSizes.get(i);
30 Log.i(TAG+"initCamera", "PictrueSize,width: " + psize.width + " height" + psize.height);
31 }
32 for (int i = 0; i < previewSizes.size(); i++)
33 {
34 psize = previewSizes.get(i);
35 Log.i(TAG+"initCamera", "PreviewSize,width: " + psize.width + " height" + psize.height);
36 }
37 Integer pf = null;
38 for (int i = 0; i < previewFormats.size(); i++)
39 {
40 pf = previewFormats.get(i);
41 Log.i(TAG+"initCamera", "previewformates:" + pf);
42 }
43
44 // 设置拍照和预览图片大小
45 parameters.setPictureSize(640, 480); //指定拍照图片的大小
46 parameters.setPreviewSize(mPreviewWidth, mPreviewHeight); // 指定preview的大小
47 //这两个属性 如果这两个属性设置的和真实手机的不一样时,就会报错
48
49 // 横竖屏镜头自动调整
50 if (this.getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE)
51 {
52 parameters.set("orientation", "portrait"); //
53 parameters.set("rotation", 90); // 镜头角度转90度(默认摄像头是横拍)
54 mCamera.setDisplayOrientation(90); // 在2.2以上可以使用
55 } else// 如果是横屏
56 {
57 parameters.set("orientation", "landscape"); //
58 mCamera.setDisplayOrientation(0); // 在2.2以上可以使用
59 }
60
61 /* 视频流编码处理 */
62 //添加对视频流处理函数
63
64
65 // 设定配置参数并开启预览
66 mCamera.setParameters(parameters); // 将Camera.Parameters设定予Camera
67 mCamera.startPreview(); // 打开预览画面
68 bIfPreview = true;
69
70 // 【调试】设置后的图片大小和预览大小以及帧率
71 Camera.Size csize = mCamera.getParameters().getPreviewSize();
72 mPreviewHeight = csize.height; //
73 mPreviewWidth = csize.width;
74 Log.i(TAG+"initCamera", "after setting, previewSize:width: " + csize.width + " height: " + csize.height);
75 csize = mCamera.getParameters().getPictureSize();
76 Log.i(TAG+"initCamera", "after setting, pictruesize:width: " + csize.width + " height: " + csize.height);
77 Log.i(TAG+"initCamera", "after setting, previewformate is " + mCamera.getParameters().getPreviewFormat());
78 Log.i(TAG+"initCamera", "after setting, previewframetate is " + mCamera.getParameters().getPreviewFrameRate());
79 } catch (Exception e)
80 {
81 e.printStackTrace();
82 }
83 }
84 }
说明1: 在/* 视频流编码处理 */ 中通过setPreviewCallback添加对视频流进行处理,如
mCamera.setPreviewCallback(new encoderVideo(mCamera.getParameters().getPreviewSize().width,
mCamera.getParameters().getPreviewSize().height,(ImageView) findViewById(R.id.ImageView2)));//①原生yuv420sp视频存储方式
mCamera.setPreviewCallback(new encoderH264(mCamera.getParameters().getPreviewSize().width,
mCamera.getParameters().getPreviewSize().height)); //②x264编码方式
mCamera.setPreviewCallback(mJpegPreviewCallback); //③JPEG压缩方式
说明2: 当然也可以不在主Acitivity中实现SurfaceHolder.Callback接口,而是在①的initSurfaceView中的addCallback函数,修改为
mSurfaceHolder.addCallback(new MyCallback); 再在这函数中实现上述三个回调函数
③视频帧回调接口
1 // 【获取视频预览帧的接口】
2 mJpegPreviewCallback =
new Camera.PreviewCallback()
3 {
4 @Override
5 public void onPreviewFrame(
byte[] data, Camera camera)
6 {
7 //传递进来的data,默认是YUV420SP的
8 // TODO Auto-generated method stub
9 try10 {
11 Log.i(TAG, "going into onPreviewFrame");
12 //mYUV420sp = data; // 获取原生的YUV420SP数据
13 YUVIMGLEN = data.length;
14 15 // 拷贝原生yuv420sp数据
16 mYuvBufferlock.acquire();
17 System.arraycopy(data, 0, mYUV420SPSendBuffer, 0, data.length);
18 //System.arraycopy(data, 0, mWrtieBuffer, 0, data.length);
19 mYuvBufferlock.release();
20 21 // 开启编码线程,如开启PEG编码方式线程
22 mSendThread1.start();
23 24 }
catch (Exception e)
25 {
26 Log.v("System.out", e.toString());
27 }
// endtry
28 }
// endonPriview
29 };
Refs/Related
0 http://developer.android.com/reference/android/graphics/Camera.html
1
2 http://www.cnblogs.com/franksunny/archive/2011/11/17/2252926.html
3 http://blog.csdn.net/yf210yf/article/details/7304437
4
5 http://developer.android.com/reference/android/view/SurfaceView.html
6 http://developer.android.com/reference/android/view/SurfaceHolder.html
7 http://blog.csdn.net/xiaominghimi/article/details/6089594
8 http://blog.csdn.net/xiaominghimi/article/details/6090575
9 http://www.cnblogs.com/emily1314/archive/2012/03/03/2378147.html
10 http://blog.csdn.net/hellogv/article/details/5985090