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use rayon::join;
use std::{
io::{stdin, stdout, Read, Write},
time::Instant,
};
const WIDTH: usize = 1920;
const HEIGHT: usize = 1080;
fn main() {
let mut oframe = Frame::new();
let mut dframe = Frame::new();
let mut out = Vec::<u8>::new();
let do_debug = false;
loop {
let timer = Instant::now();
let iframe = Frame::read(stdin());
let t = encode(&oframe, &iframe, Area::root());
decode(&mut oframe, Area::root(), &t);
write(&mut out, &t);
if do_debug {
dframe.0.copy_from_slice(&oframe.0);
debug(&mut dframe, Area::root(), &t);
dframe.write(stdout());
} else {
oframe.write(stdout());
}
eprintln!(
"compression={:.01} time={:?}",
(WIDTH * HEIGHT * 3) as f64 / out.len() as f64,
timer.elapsed()
);
out.clear();
}
}
pub fn write(w: &mut Vec<u8>, t: &DiffTree) {
match t {
DiffTree::Split([a, b]) => {
w.push(0);
write(w, a);
write(w, b);
}
DiffTree::Diff(d) => w.extend([1, d.0[0] as u8, d.0[1] as u8, d.0[2] as u8]),
}
}
pub fn decode(f: &mut Frame, area: Area, tree: &DiffTree) {
match tree {
DiffTree::Split([ta, tb]) => {
let (aa, ab) = area.split();
decode(f, aa, ta);
decode(f, ab, tb);
}
DiffTree::Diff(diff) => {
f.apply_area_diff(area, *diff);
}
}
}
pub fn debug(f: &mut Frame, area: Area, tree: &DiffTree) {
match tree {
DiffTree::Split([ta, tb]) => {
let (aa, ab) = area.split();
decode(f, aa, ta);
decode(f, ab, tb);
}
DiffTree::Diff(_diff) => {
let Area { x1, y1, x2, y2 } = area;
for x in x1..x2 {
for y in y1..y2 {
let o = (x + y * WIDTH) * 3;
f.0[o + 0] = 255;
f.0[o + 1] = 0;
f.0[o + 2] = 255;
}
}
}
}
}
pub fn encode(a: &Frame, b: &Frame, area: Area) -> DiffTree {
if area.area() == 1 {
DiffTree::Diff(Frame::diff_pixel(a, b, area.x1, area.y1))
} else {
let (aa, ba) = area.split();
let (at, bt) = join(|| encode(a, b, aa), || encode(a, b, ba));
match (&at, &bt) {
(DiffTree::Diff(ad), DiffTree::Diff(bd)) => {
let d_r = ad.0[0].abs_diff(bd.0[0]);
let d_g = ad.0[1].abs_diff(bd.0[1]);
let d_b = ad.0[2].abs_diff(bd.0[2]);
let visdiff = (d_r as usize + d_g as usize + d_b as usize) * aa.area();
if visdiff < 100 {
return DiffTree::Diff(PixelDiff([
((ad.0[0] as i16 + bd.0[0] as i16) / 2) as i8,
((ad.0[1] as i16 + bd.0[1] as i16) / 2) as i8,
((ad.0[2] as i16 + bd.0[2] as i16) / 2) as i8,
]));
}
}
_ => (),
}
DiffTree::Split([Box::new(at), Box::new(bt)])
}
}
pub enum DiffTree {
Split([Box<DiffTree>; 2]),
Diff(PixelDiff),
}
#[derive(Debug)]
pub struct Frame(Vec<u8>);
#[derive(Debug, Clone, Copy)]
pub struct PixelDiff([i8; 3]);
#[derive(Debug, Clone, Copy)]
pub struct Area {
x1: usize,
y1: usize,
x2: usize,
y2: usize,
}
#[inline]
fn diff_clamp(x: u8, y: u8) -> i8 {
if y >= x {
(y - x).min(127) as i8
} else {
-((x - y).min(128) as i8)
}
}
impl Frame {
pub fn new() -> Self {
Self(vec![0u8; WIDTH * HEIGHT * 3])
}
pub fn read(mut r: impl Read) -> Self {
let mut f = Frame::new();
r.read_exact(&mut f.0).unwrap();
f
}
pub fn write(&self, mut w: impl Write) {
w.write_all(&self.0).unwrap()
}
pub fn diff_pixel(a: &Frame, b: &Frame, x: usize, y: usize) -> PixelDiff {
let o = (x + y * WIDTH) * 3;
PixelDiff([
diff_clamp(a.0[o + 0], b.0[o + 0]),
diff_clamp(a.0[o + 1], b.0[o + 1]),
diff_clamp(a.0[o + 2], b.0[o + 2]),
])
}
pub fn apply_area_diff(&mut self, Area { x1, y1, x2, y2 }: Area, p: PixelDiff) {
for x in x1..x2 {
for y in y1..y2 {
let o = (x + y * WIDTH) * 3;
self.0[o + 0] = self.0[o + 0].saturating_add_signed(p.0[0]);
self.0[o + 1] = self.0[o + 1].saturating_add_signed(p.0[1]);
self.0[o + 2] = self.0[o + 2].saturating_add_signed(p.0[2]);
}
}
}
// pub fn average_area_diff(
// &self,
// other: &Frame,
// area @ Area { x1, y1, x2, y2 }: Area,
// ) -> PixelDiff {
// let (mut r, mut g, mut b) = (0i32, 0i32, 0i32);
// for x in x1..x2 {
// for y in y1..y2 {
// let o = (x + y * WIDTH) * 3;
// r += other.0[o + 0] as i32 - self.0[o + 0] as i32;
// g += other.0[o + 1] as i32 - self.0[o + 1] as i32;
// b += other.0[o + 2] as i32 - self.0[o + 2] as i32;
// }
// }
// let a = area.area() as i32;
// PixelDiff([
// (r / a).clamp(i8::MIN as i32, i8::MAX as i32) as i8,
// (g / a).clamp(i8::MIN as i32, i8::MAX as i32) as i8,
// (b / a).clamp(i8::MIN as i32, i8::MAX as i32) as i8,
// ])
// }
}
impl Area {
pub fn area(&self) -> usize {
self.width() as usize * self.height() as usize
}
pub fn width(&self) -> usize {
self.x2 - self.x1
}
pub fn height(&self) -> usize {
self.y2 - self.y1
}
pub fn root() -> Self {
Area {
x1: 0,
y1: 0,
x2: WIDTH,
y2: HEIGHT,
}
}
pub fn split(&self) -> (Self, Self) {
let Area { x1, y1, x2, y2 } = *self;
if self.width() > self.height() {
let xm = (self.x1 + self.x2) / 2;
(Self { x1, x2: xm, y1, y2 }, Self { x1: xm, x2, y1, y2 })
} else {
let ym = (self.y1 + self.y2) / 2;
(Self { x1, x2, y1, y2: ym }, Self { x1, x2, y1: ym, y2 })
}
}
}
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