workspace

1 files changed, 221 insertions, 0 deletions

diff --git a/difftree/src/main.rs b/difftree/src/main.rs
new file mode 100644
index 0000000..b2144a3
--- /dev/null
+++ b/difftree/src/main.rs
@@ -0,0 +1,221 @@
+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 })
+        }
+    }
+}