I420Frame转YuvImage

private YuvImage i420ToYuvImage(ByteBuffer[] yuvPlanes, int[] yuvStrides, int width, int height) {
    if (yuvStrides[0] != width) {
        return fastI420ToYuvImage(yuvPlanes, yuvStrides, width, height);
    }
    if (yuvStrides[1] != width / 2) {
        return fastI420ToYuvImage(yuvPlanes, yuvStrides, width, height);
    }
    if (yuvStrides[2] != width / 2) {
        return fastI420ToYuvImage(yuvPlanes, yuvStrides, width, height);
    }

    byte[] bytes = new byte[yuvStrides[0] * height +
            yuvStrides[1] * height / 2 +
            yuvStrides[2] * height / 2];
    ByteBuffer tmp = ByteBuffer.wrap(bytes, 0, width * height);
    copyPlane(yuvPlanes[0], tmp);

    byte[] tmpBytes = new byte[width / 2 * height / 2];
    tmp = ByteBuffer.wrap(tmpBytes, 0, width / 2 * height / 2);

    copyPlane(yuvPlanes[2], tmp);
    for (int row = 0; row < height / 2; row++) {
        for (int col = 0; col < width / 2; col++) {
            bytes[width * height + row * width + col * 2]
                    = tmpBytes[row * width / 2 + col];
        }
    }
    copyPlane(yuvPlanes[1], tmp);
    for (int row = 0; row < height / 2; row++) {
        for (int col = 0; col < width / 2; col++) {
            bytes[width * height + row * width + col * 2 + 1] =
                    tmpBytes[row * width / 2 + col];
        }
    }
    return new YuvImage(bytes, NV21, width, height, null);
}

private YuvImage fastI420ToYuvImage(ByteBuffer[] yuvPlanes,
                                    int[] yuvStrides,
                                    int width,
                                    int height) {
    byte[] bytes = new byte[width * height * 3 / 2];
    int i = 0;
    for (int row = 0; row < height; row++) {
        for (int col = 0; col < width; col++) {
            bytes[i++] = yuvPlanes[0].get(col + row * yuvStrides[0]);
        }
    }
    for (int row = 0; row < height / 2; row++) {
        for (int col = 0; col < width / 2; col++) {
            bytes[i++] = yuvPlanes[2].get(col + row * yuvStrides[2]);
            bytes[i++] = yuvPlanes[1].get(col + row * yuvStrides[1]);
        }
    }
    return new YuvImage(bytes, NV21, width, height, null);
}

private void copyPlane(ByteBuffer src, ByteBuffer dst) {
    src.position(0).limit(src.capacity());
    dst.put(src);
    dst.position(0).limit(dst.capacity());
}