Android(安卓)使用 Android(安卓)Camera API 完成音视频的采集、编码、封包成 mp4 输出

使用 Android Camera API 完成音视频的采集、编码、封包成 mp4 输出
基于android.hardware.Camera，创建一个横屏应用，实时预览摄像头图像，实现录像并输出MP4的功能。
申请权限

在activity中动态申请权限

private static final String[] VIDEO_PERMISSIONS = {        Manifest.permission.CAMERA,        Manifest.permission.RECORD_AUDIO,        Manifest.permission.WRITE_EXTERNAL_STORAGE};

实现摄像头预览功能

使用SurfaceView来预览。新建CameraPreview类继承自SurfaceView并实现SurfaceHolder.Callback；
camera相关操作都放在这个View里。

surfaceCreated中获取Camera实例，启动预览；设置预览相关参数
surfaceDestroyed释放Camera

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {    private SurfaceHolder mHolder;    private Camera mCamera;    public static final int MEDIA_TYPE_IMAGE = 1;    public static final int MEDIA_TYPE_VIDEO = 2;    private static int mOptVideoWidth = 1920;  // 默认视频帧宽度    private static int mOptVideoHeight = 1080;    private Uri outputMediaFileUri;    private String outputMediaFileType;    public CameraPreview(Context context) {        super(context);        mHolder = getHolder();        mHolder.addCallback(this);    }    private static Camera getCameraInstance() {        Camera c = null;        try {            c = Camera.open();        } catch (Exception e) {            Log.d(TAG, "camera is not available");        }        return c;    }    @Override    public void surfaceCreated(SurfaceHolder holder) {        mCamera = getCameraInstance();        try {            mCamera.setPreviewDisplay(holder);            mCamera.startPreview();            getCameraOptimalVideoSize(); // 找到最合适的分辨率        } catch (IOException e) {            Log.d(TAG, "Error setting camera preview: " + e.getMessage());        }    }    private void getCameraOptimalVideoSize() {        try {            Camera.Parameters parameters = mCamera.getParameters();            List mSupportedPreviewSizes = parameters.getSupportedPreviewSizes();            List mSupportedVideoSizes = parameters.getSupportedVideoSizes();            Camera.Size optimalSize = CameraHelper.getOptimalVideoSize(mSupportedVideoSizes,                    mSupportedPreviewSizes, getWidth(), getHeight());            mOptVideoWidth = optimalSize.width;            mOptVideoHeight = optimalSize.height;            Log.d(TAG, "prepareVideoRecorder: optimalSize:" + mOptVideoWidth + ", " + mOptVideoHeight);        } catch (Exception e) {            Log.e(TAG, "getCameraOptimalVideoSize: ", e);        }    }    @Override    public void surfaceDestroyed(SurfaceHolder holder) {        mHolder.removeCallback(this);        mCamera.setPreviewCallback(null);        mCamera.stopPreview();        mCamera.release();        mCamera = null;    }    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {    }}

在Fragment中显示摄像头预览

预置一个FrameLayout，实例化一个CameraPreview添加进去

/** * 视频录制界面 * Created by Rust on 2018/5/17. */public class VideoRecordFragment extends Fragment {    private static final String TAG = "rustAppVideoFrag";    private Button mCaptureBtn;    private CameraPreview mCameraPreview;    public static VideoRecordFragment newInstance() {        return new VideoRecordFragment();    }    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Log.d(TAG, "frag onCreate");    }    @Nullable    @Override    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        Log.d(TAG, "frag onCreateView");        return inflater.inflate(R.layout.frag_video_record, container, false);    }    @Override    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {        Log.d(TAG, "frag onViewCreated");        super.onViewCreated(view, savedInstanceState);        mCaptureBtn = view.findViewById(R.id.capture_btn);        //mCaptureBtn.setOnClickListener(mOnClickListener);// 录制键        mCameraPreview = new CameraPreview(getContext());        FrameLayout preview = view.findViewById(R.id.camera_preview);        preview.addView(mCameraPreview);    }}

使用MediaRecorder录制

给MediaRecorder指定参数后，调用start()开始录制，stop()结束录制

录制开始前，获取camera，mCamera.unlock()解锁；录制完毕后，清除MediaRecorder，mCamera.lock()

private MediaRecorder mMediaRecorder;    public boolean startRecording() {        if (prepareVideoRecorder()) {            mMediaRecorder.start();            return true;        } else {            releaseMediaRecorder();        }        return false;    }    public void stopRecording() {        if (mMediaRecorder != null) {            mMediaRecorder.stop();        }        releaseMediaRecorder();    }    public boolean isRecording() {        return mMediaRecorder != null;    }    private boolean prepareVideoRecorder() {        if (null == mCamera) {            mCamera = getCameraInstance();        }        mMediaRecorder = new MediaRecorder();        mCamera.unlock();        mMediaRecorder.setCamera(mCamera);        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);        mMediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH));        mMediaRecorder.setVideoSize(mOptVideoWidth, mOptVideoHeight);        mMediaRecorder.setOutputFile(getOutputMediaFile(MEDIA_TYPE_VIDEO).toString());        mMediaRecorder.setPreviewDisplay(mHolder.getSurface());        try {            mMediaRecorder.prepare();        } catch (IllegalStateException e) {            Log.d(TAG, "IllegalStateException preparing MediaRecorder: " + e.getMessage());            releaseMediaRecorder();            return false;        } catch (IOException e) {            Log.d(TAG, "IOException preparing MediaRecorder: " + e.getMessage());            releaseMediaRecorder();            return false;        }        return true;    }    private void releaseMediaRecorder() {        if (mMediaRecorder != null) {            mMediaRecorder.reset();            mMediaRecorder.release();            mMediaRecorder = null;            mCamera.lock();        }    }    private File getOutputMediaFile(int type) {        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(                Environment.DIRECTORY_PICTURES), TAG);        if (!mediaStorageDir.exists()) {            if (!mediaStorageDir.mkdirs()) {                Log.d(TAG, "failed to create directory");                return null;            }        }        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.CHINA).format(new Date());        File mediaFile;        if (type == MEDIA_TYPE_IMAGE) {            mediaFile = new File(mediaStorageDir.getPath() + File.separator +                    "IMG_" + timeStamp + ".jpg");            outputMediaFileType = "image/*";        } else if (type == MEDIA_TYPE_VIDEO) {            mediaFile = new File(mediaStorageDir.getPath() + File.separator +                    "VID_" + timeStamp + ".mp4");            outputMediaFileType = "video/*";        } else {            return null;        }        outputMediaFileUri = Uri.fromFile(mediaFile);        return mediaFile;    }

后台返回时预览黑屏的问题

CameraPreview是我们在Fragment创建时实例化并添加进去的。
应用退到后台后，CameraPreview已经被销毁。应用回到前台时，我们应该在onResume方法中进行操作。恢复CameraPreview。

在Fragment中，判断销毁和重建预览的时机。

@Overridepublic void onPause() {    super.onPause();    Log.d(TAG, "onPause: 销毁预览");    mCameraPreview = null;}@Overridepublic void onResume() {    super.onResume();    Log.d(TAG, "onResume: 回到前台");    if (null == mCameraPreview) {        initCameraPreview();    }}private void initCameraPreview() {    mCameraPreview = new CameraPreview(getContext());    FrameLayout preview = mRoot.findViewById(R.id.camera_preview);    preview.addView(mCameraPreview);}

相关代码请参阅： https://github.com/changhaismile/CameraRecorder

实现摄像头预览功能

在Fragment中显示摄像头预览

使用MediaRecorder录制

后台返回时预览黑屏的问题

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