很多Android系统上的应用需要采集摄像头图像,并把图像编码成某种格式(比如H264),保存成文件或发送到网络。虽然有FFmpeg可以实现编码的功能,但是使用软编码一方面比较耗电,另一方面,对于CPU性能不是太强的ARM设备来说,软件编码肯定很占CPU资源,有些旧的机器甚至一编码就卡机。从Android 4.1系统起,引进了MediaCodec API,可以实现硬编码的功能,这解决了广大程序员编码视频的难题,但是这套API使用起来并不简单,有很多细节要注意,很容易掉进一些坑,下面我会讲解怎么越过那些坑,但是首先我先用代码说明一下怎么在Android上调用摄像头的API来采集图像。
- 采集摄像头图像
public class MainActivity extends Activity {
private SurfaceView surfaceView;
private Camera camera;
private SurfaceHolder surfaceHolder;
private Camera.Parameters mParameters = null;
@SuppressLint("InlinedApi")
private int mCameraId = Camera.CameraInfo.CAMERA_FACING_BACK;
// 不同手机有不同的匹配颜色
private int width = 1280;
private int height = 720;
private int mFrameRate = 25;
private int bitrate = 800*1024;
byte[] h264 = new byte[width * height * 3 / 2];
byte[] mPreBuffer = null;
private AvcEncode avcEncode;
private Button button1;
private Button button2;
private TextView labelFrameRate;
private TextView labelCPULevel;
Timer timer = null;
Boolean m_bRunning = false;
private long mLastStartCountTime = 0;
private int mFrameCapturedCountInCycle = 0;
static {
// System.loadLibrary("gnustl_shared");
System.loadLibrary("songstudio");
}
//EncodeVideo EncoderJni = new EncodeVideo(); //构建软解编码器
@SuppressWarnings("deprecation")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setContentView(R.layout.activity_main);
button1 = (Button) findViewById(R.id.btn_start_preview);
button2 = (Button) findViewById(R.id.btn_stop_preview);
labelFrameRate = (TextView) findViewById(R.id.label_framerate);
labelCPULevel = (TextView) findViewById(R.id.label_cpu_level);
avcEncode = new AvcEncode(width, height, mFrameRate, bitrate, 20);
//EncoderJni.SetFilePath(FileOperator.fileName2);
//EncoderJni.SetParameters(width, height, mFrameRate, bitrate, 25);
surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.setFixedSize(width, height);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
surfaceHolder.addCallback(new SurfaceCallback());
// Sampler.getInstance().init(getApplicationContext(), 3000L);
// Sampler.getInstance().start();
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