android bitmap nv21,NV21转bitmap的高效方式

最近在做人脸检测这块，需要把USB摄像头的byte[]数组转成bitmap显示到屏幕上，这就需要用到

public static Bitmap convertByte2Bitmap(byte[] data, int width, int height, int quality) {

Bitmap bitmap;

YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21, width, height, null);

ByteArrayOutputStream stream = new ByteArrayOutputStream();

yuvImage.compressToJpeg(new Rect(0, 0, width, height), quality, stream);

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

try {

stream.close();

} catch (IOException e) {

e.printStackTrace();

}

return bitmap;

}

此方法转换，但这个方法比较耗时，大概需要30-50毫秒 。

通过google查到了另一个方法转换，使用Renderscript内联函数，效率更快，大概几毫秒就可以转换完成。

public class NV21ToBitmap {

private RenderScript rs;

private ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic;

public NV21ToBitmap(Context context) {

rs = RenderScript.create(context);

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

}

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

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

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

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

Allocation 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;

}

}