lossy compression

encoder/src/dec.rs

@@ -1,5 +1,56 @@
 use crate::*;
 
+pub fn cell_diff_4_vertical(prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
+	const CELLS_X: usize = WIDTH / 4;
+	const CELLS_Y: usize = HEIGHT / 4;
+
+	let mut modified_cells = [[false; CELLS_Y]; CELLS_X];
+
+	let (mut cell_runs, modified_cells_flat) =
+		rle_255_decode(&unpack_nybbles(encoded), CELLS_X * CELLS_Y);
+
+	if cell_runs % 2 == 1 {
+		cell_runs += 1;
+	}
+	*reader += cell_runs / 2;
+	let encoded = &encoded[(cell_runs / 2)..];
+
+	let mut changed_cell_count = 0;
+	let mut i = 0;
+	for cellx in 0..CELLS_X {
+		for celly in 0..CELLS_Y {
+			let cell = modified_cells_flat[i] == 1;
+			modified_cells[cellx][celly] = cell;
+			if cell {
+				changed_cell_count += 1;
+			}
+			i += 1;
+		}
+	}
+
+	let mut frame = *prev_frame;
+
+	let changed_pixel_count = changed_cell_count * 4 * 4;
+	let (runs, new_pixels) = rle_255_decode(encoded, changed_pixel_count);
+	*reader += runs;
+
+	let mut index = 0;
+
+	for x in 0..WIDTH {
+		for y in 0..HEIGHT {
+			let cellx = x / 4;
+			let celly = y / 4;
+			let is_changed = modified_cells[cellx][celly];
+			if is_changed {
+				frame[x][y] = new_pixels[index];
+				index += 1;
+			}
+		}
+	}
+
+	frame
+}
+
 pub fn cell_diff_8_vertical(prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
 	let bitmap = {
 		*reader += 3;
@@ -11,7 +62,7 @@ pub fn cell_diff_8_vertical(prev_frame: &Frame, encoded: &[u8], reader: &mut usi
 
 	let mut frame = *prev_frame;
 	let changed_pixel_count = bitmap.count_ones() as usize * 8 * 8;
-	let (runs, new_pixels) = rle_255_decode_until(encoded, changed_pixel_count);
+	let (runs, new_pixels) = rle_255_decode(encoded, changed_pixel_count);
 	*reader += runs;
 
 	let cells_x = WIDTH / 8;
@@ -54,7 +105,7 @@ pub fn bg_strips_horizontal(_prev_frame: &Frame, encoded: &[u8], reader: &mut us
 }
 
 pub fn rle_diff_horizontal(prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
-	let (runs, decoded) = rle_255_decode_until(encoded, FRAME_SIZE);
+	let (runs, decoded) = rle_255_decode(encoded, FRAME_SIZE);
 	*reader += runs;
 	let mut frame = *prev_frame;
 	let mut i = 0;
@@ -68,7 +119,7 @@ pub fn rle_diff_horizontal(prev_frame: &Frame, encoded: &[u8], reader: &mut usiz
 }
 
 pub fn rle_diff_vertical(prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
-	let (runs, decoded) = rle_255_decode_until(encoded, FRAME_SIZE);
+	let (runs, decoded) = rle_255_decode(encoded, FRAME_SIZE);
 	*reader += runs;
 	let mut frame = *prev_frame;
 	let mut dbg_frame = FRAME_0;
@@ -86,7 +137,7 @@ pub fn rle_diff_vertical(prev_frame: &Frame, encoded: &[u8], reader: &mut usize)
 }
 
 pub fn rle_horizontal(_prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
-	let (runs, pixels) = rle_255_decode_until(encoded, FRAME_SIZE);
+	let (runs, pixels) = rle_255_decode(encoded, FRAME_SIZE);
 	*reader += runs;
 	let mut frame = FRAME_0;
 	let mut i = 0;
@@ -100,7 +151,7 @@ pub fn rle_horizontal(_prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -
 }
 
 pub fn rle_vertical(_prev_frame: &Frame, encoded: &[u8], reader: &mut usize) -> Frame {
-	let (runs, pixels) = rle_255_decode_until(encoded, FRAME_SIZE);
+	let (runs, pixels) = rle_255_decode(encoded, FRAME_SIZE);
 	*reader += runs;
 	let mut frame = FRAME_0;
 	let mut i = 0;

encoder/src/enc.rs

@@ -1,15 +1,66 @@
 use crate::*;
 
-pub fn cell_diff_8_vertical(prev_frame: &Frame, frame: &Frame) -> EncodedFrame {
+pub fn cell_diff_4_vertical(prev_frame: &Frame, frame: &Frame, loss: usize) -> EncodedFrame {
-	let cells_x = WIDTH / 8;
+	let loss = loss / 4;
-	let cells_y = HEIGHT / 8;
+	const CELLS_X: usize = WIDTH / 4;
-	let loss = 0;
+	const CELLS_Y: usize = HEIGHT / 4;
+
+	let mut modified_cells = [[0; CELLS_Y]; CELLS_X];
+
+	for cellx in 0..CELLS_X {
+		for celly in 0..CELLS_Y {
+			let mut changed = 0;
+			for dx in 0..4 {
+				for dy in 0..4 {
+					let x = cellx * 4 + dx;
+					let y = celly * 4 + dy;
+					let pixel = frame[x][y];
+
+					if pixel != prev_frame[x][y] {
+						changed += 1;
+					}
+				}
+			}
+			if changed > loss {
+				modified_cells[cellx][celly] = 1;
+			}
+		}
+	}
+	let mut changed_pixels = Vec::new();
+	for x in 0..WIDTH {
+		for y in 0..HEIGHT {
+			let cellx = x / 4;
+			let celly = y / 4;
+
+			if modified_cells[cellx][celly] != 0 {
+				changed_pixels.push(frame[x][y]);
+			}
+		}
+	}
+	let mut modified_cells_flat = Vec::new();
+	for x in 0..CELLS_X {
+		for y in 0..CELLS_Y {
+			modified_cells_flat.push(modified_cells[x][y]);
+		}
+	}
+	let mut data = Vec::new();
+	data.extend_from_slice(&pack_nybbles(rle_encode(&modified_cells_flat, 15)));
+	data.extend_from_slice(&rle_255_encode(&changed_pixels));
+
+	EncodedFrame {
+		encoding: Encoding::CellDiff4VV,
+		data,
+	}
+}
+
+pub fn cell_diff_8_vertical(prev_frame: &Frame, frame: &Frame, loss: usize) -> EncodedFrame {
+	const CELLS_X: usize = WIDTH / 8;
+	const CELLS_Y: usize = HEIGHT / 8;
 
 	let mut bitmap: u32 = 0;
-	let mut changed_pixels = Vec::new();
 
-	for cellx in 0..cells_x {
+	for cellx in 0..CELLS_X {
-		for celly in 0..cells_y {
+		for celly in 0..CELLS_Y {
 			let mut changed = 0;
 			for dx in 0..8 {
 				for dy in 0..8 {
@@ -23,15 +74,16 @@ pub fn cell_diff_8_vertical(prev_frame: &Frame, frame: &Frame) -> EncodedFrame {
 				}
 			}
 			if changed > loss {
-				bitmap |= 1 << (cellx + cells_x * celly);
+				bitmap |= 1 << (cellx + CELLS_X * celly);
 			}
 		}
 	}
+	let mut changed_pixels = Vec::new();
 	for x in 0..WIDTH {
 		for y in 0..HEIGHT {
 			let cellx = x / 8;
 			let celly = y / 8;
-			let bit = 1 << (cellx + cells_x * celly);
+			let bit = 1 << (cellx + CELLS_X * celly);
 			if (bitmap & bit) != 0 {
 				changed_pixels.push(frame[x][y]);
 			}
@@ -150,14 +202,14 @@ pub fn rle_vertical(_prev_frame: &Frame, frame: &Frame) -> EncodedFrame {
 	}
 }
 
-pub fn fill_white(_prev_frame: &Frame, _frame: &Frame) -> EncodedFrame {
+pub fn fill_white(_prev_frame: &Frame, _frame: &Frame, _loss: usize) -> EncodedFrame {
 	EncodedFrame {
 		encoding: Encoding::FillWhite,
 		data: Vec::new(),
 	}
 }
 
-pub fn fill_black(_prev_frame: &Frame, _frame: &Frame) -> EncodedFrame {
+pub fn fill_black(_prev_frame: &Frame, _frame: &Frame, _loss: usize) -> EncodedFrame {
 	EncodedFrame {
 		encoding: Encoding::FillBlack,
 		data: Vec::new(),

encoder/src/main.rs

@@ -8,13 +8,13 @@ pub use util::*;
 
 const INSPECT_ENC: bool = false;
 const INSPECT_DEC: bool = false;
-const MAX_ERROR: usize = 0;
+const MAX_ERROR: usize = 4; // max wrong pixels
+const MAX_LOSS: usize = 16; // highest "loss" value tried for all lossy encodings
 
 fn main() {
 	let frames = get_all_frames("../video/frames/");
 	let encoded = encode(&frames);
 
-	// todo print average bytes per frame for each encoding type
 	let mut stats: EnumMap<Encoding, u32> = EnumMap::default();
 	let mut reader = 0;
 	let mut last_frame = FRAME_0;
@@ -49,34 +49,59 @@ fn main() {
 
 fn encode(frames: &[Frame]) -> Vec<u8> {
 	let mut out = Vec::new();
-	let encodings: Vec<FrameEncoder> = vec![
+	let lossless_encodings: Vec<FrameEncoder> = vec![
-		enc::fill_white,
-		enc::fill_black,
 		enc::rle_horizontal,
 		enc::rle_vertical,
 		enc::rle_diff_horizontal,
 		enc::rle_diff_vertical,
 		enc::bg_strips_horizontal,
+	];
+	let lossy_encodings: Vec<FrameEncoderLossy> = vec![
+		enc::fill_white,
+		enc::fill_black,
 		enc::cell_diff_8_vertical,
+		enc::cell_diff_4_vertical,
 	];
 
 	let mut last_frame = FRAME_0;
-	for (i, frame) in frames.iter().enumerate() {
+	for (_i, frame) in frames.iter().enumerate() {
 		let mut options = Vec::new();
-		for encode in &encodings {
+		for encode in &lossless_encodings {
 			let encoded = encode(&last_frame, frame);
 			let decode = get_matching_decoder(encoded.encoding);
 			let decoded = decode(&last_frame, &encoded.data, &mut 0);
 			let error = frame_error(frame, &decoded);
-			if error <= MAX_ERROR {
+			if error == 0 {
 				options.push(encoded);
 			} else {
+				dbg!(&encoded);
+				println!("{:?}, error: {error}, frame: {_i}", encoded.encoding);
+				render_images(&frame, &decoded);
+				panic!("error in lossless compression");
+			}
+		}
+		for encode in &lossy_encodings {
+			for loss in 0..MAX_LOSS {
+				let encoded = encode(&last_frame, frame, loss);
+				let decode = get_matching_decoder(encoded.encoding);
+				let decoded = decode(&last_frame, &encoded.data, &mut 0);
+				let error = frame_error(frame, &decoded);
+
+				// if error > 0 && loss == 0 {
 				// 	dbg!(&encoded);
-				// println!("{:?}, error: {error}, frame: {i}", encoded.encoding);
+				// 	println!("{:?}, error: {error}, frame: {_i}", encoded.encoding);
 				// 	render_images(&frame, &decoded);
-				// panic!("loss in compression");
+				// 	panic!("error in 'loss 0' compression");
+				// }
+				if error < MAX_ERROR {
+					options.push(encoded);
+				} else {
+					// higher loss value will mean more error so can be skipped
+					break;
 				}
 			}
+		}
+
 		options.sort_by_key(|b| b.data.len());
 		let best_encoding = options.into_iter().next().unwrap();
 		if INSPECT_ENC {
@@ -99,10 +124,10 @@ fn encode(frames: &[Frame]) -> Vec<u8> {
 #[derive(Debug, TryFromPrimitive, Enum, Copy, Clone)]
 #[repr(u8)]
 enum Encoding {
-	FillWhite,
+	FillBlack = 0,
-	FillBlack,
+	FillWhite = 1,
-	RLEHorizontal,
+	RLEHorizontal = 2,
-	RLEVertical,
+	RLEVertical = 3,
 	RLEDiffHorizontal,
 	RLEDiffVertical,
 	BGStripsH,
@@ -114,7 +139,7 @@ enum Encoding {
 	// CellDiff4HH,
 	// CellDiff4HV,
 	// CellDiff4VH,
-	// CellDiff4VV,
+	CellDiff4VV,
 }
 
 fn get_matching_decoder(encoding: Encoding) -> FrameDecoder {
@@ -134,11 +159,12 @@ fn get_matching_decoder(encoding: Encoding) -> FrameDecoder {
 		// Encoding::CellDiff4HH => todo!(),
 		// Encoding::CellDiff4HV => todo!(),
 		// Encoding::CellDiff4VH => todo!(),
-		// Encoding::CellDiff4VV => todo!(),
+		Encoding::CellDiff4VV => dec::cell_diff_4_vertical,
 	}
 }
 
 type FrameEncoder = fn(previous_frame: &Frame, new_frame: &Frame) -> EncodedFrame;
+type FrameEncoderLossy = fn(previous_frame: &Frame, new_frame: &Frame, loss: usize) -> EncodedFrame;
 type FrameDecoder = fn(previous_frame: &Frame, encoded_bytes: &[u8], reader: &mut usize) -> Frame;
 
 #[derive(Debug)]

encoder/src/util.rs

@@ -107,13 +107,17 @@ pub fn render_images(left: &Frame, right: &Frame) {
 }
 
 pub fn rle_255_encode(raw: &[u8]) -> Vec<u8> {
+	rle_encode(raw, 255)
+}
+
+pub fn rle_encode(raw: &[u8], max: u8) -> Vec<u8> {
 	let mut encoded = Vec::new();
 	let mut last_val = 0;
 	let mut run = 0;
 	for &val in raw {
-		if val != last_val || run == 255 {
+		if val != last_val || run == max {
 			encoded.push(run);
-			if run == 255 && val == last_val {
+			if run == max && val == last_val {
 				encoded.push(0);
 			}
 			run = 1;
@@ -126,7 +130,31 @@ pub fn rle_255_encode(raw: &[u8]) -> Vec<u8> {
 	encoded
 }
 
-pub fn rle_255_decode_until(encoded: &[u8], max_size: usize) -> (usize, Vec<u8>) {
+pub fn pack_nybbles(mut nybbles: Vec<u8>) -> Vec<u8> {
+	if nybbles.len() % 2 == 1 {
+		nybbles.push(0);
+	}
+	assert!(nybbles.iter().all(|&n| n < 16));
+	let mut packed = Vec::with_capacity(nybbles.len() / 2);
+	for i in 0..(nybbles.len() / 2) {
+		let upper = nybbles[i * 2] << 4;
+		let lower = nybbles[i * 2 + 1] & 15;
+		let byte = upper | lower;
+		packed.push(byte);
+	}
+	packed
+}
+
+pub fn unpack_nybbles(packed: &[u8]) -> Vec<u8> {
+	let mut nybbles = Vec::with_capacity(packed.len() * 2);
+	for &p in packed {
+		nybbles.push(p >> 4);
+		nybbles.push(p & 15);
+	}
+	nybbles
+}
+
+pub fn rle_255_decode(encoded: &[u8], max_size: usize) -> (usize, Vec<u8>) {
 	let mut raw = Vec::new();
 	let mut val = 0;
 	let mut consumed_bytes = 0;