NV21.kt

fun Bitmap.bitmapToNV21ByteArray(): ByteArray {
        val argb = IntArray(this.width * this.height)
        this.getPixels(argb, 0, this.width, 0, 0, this.width, this.height)
        val yuv = ByteArray(
            this.height * this.width + 2 * ceil(this.height / 2.0).toInt()
                    * ceil(this.width / 2.0).toInt()
        )
        encodeYUV420SP(yuv, argb, this.width, this.height)
        return yuv
    }

private fun encodeYUV420SP(yuv420sp: ByteArray, argb: IntArray, width: Int, height: Int) {
        val frameSize = width * height
        var yIndex = 0
        var uvIndex = frameSize
        var r: Int
        var g: Int
        var b: Int
        var y: Int
        var u: Int
        var v: Int
        var index = 0
        for (j in 0 until height) {
            for (i in 0 until width) {
                r = argb[index] and 0xff0000 shr 16
                g = argb[index] and 0xff00 shr 8
                b = argb[index] and 0xff shr 0
                y = (66 * r + 129 * g + 25 * b + 128 shr 8) + 16
                u = (-38 * r - 74 * g + 112 * b + 128 shr 8) + 128
                v = (112 * r - 94 * g - 18 * b + 128 shr 8) + 128
                yuv420sp[yIndex++] = (if (y < 0) 0 else if (y > 255) 255 else y).toByte()
                if (j % 2 == 0 && index % 2 == 0) {
                    yuv420sp[uvIndex++] = (if (v < 0) 0 else if (v > 255) 255 else v).toByte()
                    yuv420sp[uvIndex++] = (if (u < 0) 0 else if (u > 255) 255 else u).toByte()
                }
                index++
            }
        }
    }