使用Android Camera API检测视频大小的步骤：

步骤1：创建一个类来处理提取视频文件的信息和元数据。

public class VideoUtils {
 
    public static BitmapFactory.Options getVideoDimensions(String videoPath) {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        MediaPlayer mp = MediaPlayer.create(context, Uri.parse(videoPath));
        int height = mp.getVideoHeight();
        int width = mp.getVideoWidth();
        return options;
    }
}

步骤2：添加权限到AndroidManifest.xml文件，以便访问存储和摄像头。

步骤3：在Activity中调用VideoUtils类中的方法来获取视频的大小。

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_VIDEO_CAPTURE = 1;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        Button recordButton = findViewById(R.id.record_button);
        recordButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dispatchTakeVideoIntent();
            }
        });
    }
 
    private void dispatchTakeVideoIntent() {
        Intent takeVideoIntent = new Intent(MediaStore.ACTION_VIDEO_CAPTURE);
        if (takeVideoIntent.resolveActivity(getPackageManager()) != null) {
            startActivityForResult(takeVideoIntent, REQUEST_VIDEO_CAPTURE);
        }
    }
 
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_VIDEO_CAPTURE && resultCode == RESULT_OK) {
            Uri videoUri = data.getData();
            String path= videoUri.getPath();
            BitmapFactory.Options dimensions = VideoUtils.getVideoDimensions(path);
            int height = dimensions.outHeight;
            int width = dimensions.outWidth;
        }
    }
}

这样就可以通过使用Android Camera API检测视频大小了。