通常用Camera 采集视频 得到预览数据，使用mediaCodec获取视频数据，用mediaMuxer进行音视频的混流，

如果想要添加水印很简单：

1、拿到相机预览的帧数据

2、将帧数据转为Bitmap

3、在Bitmap上添加水印(文字或者图片)

4、将图片转为帧数据

然后继续混流，效果如下：

拿相机预览的数据很简单：

关键在第二步，帧数据转为bitmap常规是这样做的  但是这种做法很耗时会导致视频卡顿：

YuvImage image = new YuvImage(dst, ImageFormat.NV21, CameraSettings.SRC_IMAGE_WIDTH,CameraSettings.SRC_IMAGE_HEIGHT, null)

ByteArrayOutputStream stream = new ByteArrayOutputStream();

image.compressToJpeg(new Rect(0, 0, CameraSettings.SRC_IMAGE_WIDTH,CameraSettings.SRC_IMAGE_HEIGHT), 100, stream);

Bitmap bitmapAll = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());

比较好的做法是使用 RenderScript的内联函数 可以更加高效的将帧数据转为bitmap：

public class MyClass {

private RenderScript rs;

private ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic;

private Type.Builder yuvType, rgbaType;

private Allocation in, out;

public MyClass(Context context) {

rs = RenderScript.create(context);

yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));

}

public Bitmap nv21ToBitmap(byte[] nv21, int width, int height){

if (yuvType == null){

yuvType = new Type.Builder(rs, Element.U8(rs)).setX(nv21.length);

in = Allocation.createTyped(rs, yuvType.create(), Allocation.USAGE_SCRIPT);

rgbaType = new Type.Builder(rs, Element.RGBA_8888(rs)).setX(width).setY(height);

out = Allocation.createTyped(rs, rgbaType.create(), Allocation.USAGE_SCRIPT);

}

in.copyFrom(nv21);

yuvToRgbIntrinsic.setInput(in);

yuvToRgbIntrinsic.forEach(out);

Bitmap bmpout = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

out.copyTo(bmpout);

return bmpout;

}

}

所以第二步、第三步可以这样使用：

/**

* 将拿到的预览帧数据转为bitmap添加水印 再讲bitmap转为帧数据

* @param dst 预览的帧数据

* @return

*/

private byte[] dealByte(byte[] dst) {

// YuvImage image = new YuvImage(dst, ImageFormat.NV21, CameraSettings.SRC_IMAGE_WIDTH,CameraSettings.SRC_IMAGE_HEIGHT, null)

// ByteArrayOutputStream stream = new ByteArrayOutputStream();

// image.compressToJpeg(new Rect(0, 0, CameraSettings.SRC_IMAGE_WIDTH,CameraSettings.SRC_IMAGE_HEIGHT), 100, stream);

// Bitmap bitmapAll = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());

Bitmap bitmapAll = myClass.nv21ToBitmap(dst, CameraSettings.SRC_IMAGE_WIDTH,

CameraSettings.SRC_IMAGE_HEIGHT);

Bitmap bitmapAllNew=bitmapAll.copy(Bitmap.Config.ARGB_8888,true);

Canvas canvas = new Canvas(bitmapAllNew);

Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);

paint.setColor(Color.WHITE);

paint.setTextSize(80);

canvas.drawText("毕哥制作", CameraSettings.SRC_IMAGE_WIDTH/2, 100, paint);

byte[] newBytes = bitmapToNv21(bitmapAllNew,CameraSettings.SRC_IMAGE_WIDTH, CameraSettings.SRC_IMAGE_HEIGHT);

if(newBytes!=null){

return newBytes;

}else{

return null;

}

}

bitmap转为帧数据

public static byte[] bitmapToNv21(Bitmap src, int width, int height) {

if (src != null && src.getWidth() >= width && src.getHeight() >= height) {

int[] argb = new int[width * height];

src.getPixels(argb, 0, width, 0, 0, width, height);

return argbToNv21(argb, width, height);

} else {

return null;

}

}

最后再将帧数据 通过mediaCodec编码，再用mediaMuxer进行音视频混流即可