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cdef.rs
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cdef.rs
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// Copyright (c) 2017-2022, The rav1e contributors. All rights reserved
//
// This source code is subject to the terms of the BSD 2 Clause License and
// the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
// was not distributed with this source code in the LICENSE file, you can
// obtain it at www.aomedia.org/license/software. If the Alliance for Open
// Media Patent License 1.0 was not distributed with this source code in the
// PATENTS file, you can obtain it at www.aomedia.org/license/patent.
use crate::color::ChromaSampling::Cs400;
use crate::context::*;
use crate::encoder::FrameInvariants;
use crate::frame::*;
use crate::tiling::*;
use crate::util::{clamp, msb, CastFromPrimitive, Pixel};
use crate::cpu_features::CpuFeatureLevel;
use std::cmp;
cfg_if::cfg_if! {
if #[cfg(nasm_x86_64)] {
pub(crate) use crate::asm::x86::cdef::*;
} else if #[cfg(asm_neon)] {
pub(crate) use crate::asm::aarch64::cdef::*;
} else {
pub(crate) use self::rust::*;
}
}
pub const CDEF_VERY_LARGE: u16 = 0x8000;
// These values match dav1d; flags indicating where padding exists
pub const CDEF_HAVE_LEFT: u8 = 1 << 0;
pub const CDEF_HAVE_RIGHT: u8 = 1 << 1;
pub const CDEF_HAVE_TOP: u8 = 1 << 2;
pub const CDEF_HAVE_BOTTOM: u8 = 1 << 3;
pub const CDEF_HAVE_ALL: u8 =
CDEF_HAVE_LEFT | CDEF_HAVE_RIGHT | CDEF_HAVE_TOP | CDEF_HAVE_BOTTOM;
pub(crate) const CDEF_SEC_STRENGTHS: u8 = 4;
pub struct CdefDirections {
dir: [[u8; 8]; 8],
var: [[i32; 8]; 8],
}
pub(crate) mod rust {
use super::*;
use simd_helpers::cold_for_target_arch;
// Instead of dividing by n between 2 and 8, we multiply by 3*5*7*8/n.
// The output is then 840 times larger, but we don't care for finding
// the max.
const CDEF_DIV_TABLE: [i32; 9] = [0, 840, 420, 280, 210, 168, 140, 120, 105];
/// Returns the position and value of the first instance of the max element in
/// a slice as a tuple.
///
/// # Arguments
///
/// * `elems` - A non-empty slice of integers
///
/// # Panics
///
/// Panics if `elems` is empty
#[inline]
fn first_max_element(elems: &[i32]) -> (usize, i32) {
// In case of a tie, the first element must be selected.
let (max_idx, max_value) = elems
.iter()
.enumerate()
.max_by_key(|&(i, v)| (v, -(i as isize)))
.unwrap();
(max_idx, *max_value)
}
// Detect direction. 0 means 45-degree up-right, 2 is horizontal, and so on.
// The search minimizes the weighted variance along all the lines in a
// particular direction, i.e. the squared error between the input and a
// "predicted" block where each pixel is replaced by the average along a line
// in a particular direction. Since each direction have the same sum(x^2) term,
// that term is never computed. See Section 2, step 2, of:
// http://jmvalin.ca/notes/intra_paint.pdf
pub fn cdef_find_dir<T: Pixel>(
img: &PlaneSlice<'_, T>, var: &mut u32, coeff_shift: usize,
_cpu: CpuFeatureLevel,
) -> i32 {
let mut cost: [i32; 8] = [0; 8];
let mut partial: [[i32; 15]; 8] = [[0; 15]; 8];
for i in 0..8 {
for j in 0..8 {
let p: i32 = i32::cast_from(img[i][j]);
// We subtract 128 here to reduce the maximum range of the squared
// partial sums.
debug_assert!(p >> coeff_shift <= 255);
let x = (p >> coeff_shift) - 128;
partial[0][i + j] += x;
partial[1][i + j / 2] += x;
partial[2][i] += x;
partial[3][3 + i - j / 2] += x;
partial[4][7 + i - j] += x;
partial[5][3 - i / 2 + j] += x;
partial[6][j] += x;
partial[7][i / 2 + j] += x;
}
}
for i in 0..8 {
cost[2] += partial[2][i] * partial[2][i];
cost[6] += partial[6][i] * partial[6][i];
}
cost[2] *= CDEF_DIV_TABLE[8];
cost[6] *= CDEF_DIV_TABLE[8];
for i in 0..7 {
cost[0] += (partial[0][i] * partial[0][i]
+ partial[0][14 - i] * partial[0][14 - i])
* CDEF_DIV_TABLE[i + 1];
cost[4] += (partial[4][i] * partial[4][i]
+ partial[4][14 - i] * partial[4][14 - i])
* CDEF_DIV_TABLE[i + 1];
}
cost[0] += partial[0][7] * partial[0][7] * CDEF_DIV_TABLE[8];
cost[4] += partial[4][7] * partial[4][7] * CDEF_DIV_TABLE[8];
for i in (1..8).step_by(2) {
for j in 0..5 {
cost[i] += partial[i][3 + j] * partial[i][3 + j];
}
cost[i] *= CDEF_DIV_TABLE[8];
for j in 0..3 {
cost[i] += (partial[i][j] * partial[i][j]
+ partial[i][10 - j] * partial[i][10 - j])
* CDEF_DIV_TABLE[2 * j + 2];
}
}
let (best_dir, best_cost) = first_max_element(&cost);
// Difference between the optimal variance and the variance along the
// orthogonal direction. Again, the sum(x^2) terms cancel out.
// We'd normally divide by 840, but dividing by 1024 is close enough
// for what we're going to do with this. */
*var = ((best_cost - cost[(best_dir + 4) & 7]) >> 10) as u32;
best_dir as i32
}
#[inline(always)]
fn constrain(diff: i32, threshold: i32, damping: i32) -> i32 {
if threshold != 0 {
let shift = cmp::max(0, damping - msb(threshold));
let magnitude = (threshold - (diff.abs() >> shift)).clamp(0, diff.abs());
if diff < 0 {
-magnitude
} else {
magnitude
}
} else {
0
}
}
pub unsafe fn pad_into_tmp16<T: Pixel>(
dst: *mut u16, dst_stride: isize, src: *const T, src_stride: isize,
block_width: usize, block_height: usize, edges: u8,
) {
let mut w = block_width;
let mut h = block_height;
let (dst_col, src_col) = if (edges & CDEF_HAVE_LEFT) != 0 {
w += 2;
(dst, src.offset(-2))
} else {
(dst.offset(2), src)
};
if (edges & CDEF_HAVE_RIGHT) != 0 {
w += 2;
};
let (mut dst_ptr, mut src_ptr) = if (edges & CDEF_HAVE_TOP) != 0 {
h += 2;
(dst_col, src_col.offset(-2 * src_stride))
} else {
(dst_col.offset(2 * dst_stride), src_col)
};
if (edges & CDEF_HAVE_BOTTOM) != 0 {
h += 2;
};
for _y in 0..h {
for x in 0..w {
*dst_ptr.add(x) = u16::cast_from(*src_ptr.add(x));
}
src_ptr = src_ptr.offset(src_stride);
dst_ptr = dst_ptr.offset(dst_stride);
}
}
#[cold_for_target_arch("x86_64")]
#[allow(clippy::erasing_op, clippy::identity_op, clippy::neg_multiply)]
pub(crate) unsafe fn cdef_filter_block<T: Pixel, U: Pixel>(
dst: &mut PlaneRegionMut<'_, T>, input: *const U, istride: isize,
pri_strength: i32, sec_strength: i32, dir: usize, damping: i32,
bit_depth: usize, xdec: usize, ydec: usize, edges: u8,
_cpu: CpuFeatureLevel,
) {
if edges != CDEF_HAVE_ALL {
// slowpath for unpadded border[s]
let tmpstride = 2 + (8 >> xdec) + 2;
let mut tmp = [CDEF_VERY_LARGE; (2 + 8 + 2) * (2 + 8 + 2)];
// copy in what pixels we have/are allowed to use
pad_into_tmp16(
tmp.as_mut_ptr(), // points to *padding* upper left
tmpstride,
input, // points to *block* upper left
istride,
8 >> xdec,
8 >> ydec,
edges,
);
cdef_filter_block(
dst,
tmp.as_ptr().offset(2 * tmpstride + 2),
tmpstride,
pri_strength,
sec_strength,
dir,
damping,
bit_depth,
xdec,
ydec,
CDEF_HAVE_ALL,
_cpu,
);
} else {
let xsize = (8 >> xdec) as isize;
let ysize = (8 >> ydec) as isize;
let coeff_shift = bit_depth - 8;
let cdef_pri_taps = [[4, 2], [3, 3]];
let cdef_sec_taps = [[2, 1], [2, 1]];
let pri_taps =
cdef_pri_taps[((pri_strength >> coeff_shift) & 1) as usize];
let sec_taps =
cdef_sec_taps[((pri_strength >> coeff_shift) & 1) as usize];
let cdef_directions = [
[-1 * istride + 1, -2 * istride + 2],
[0 * istride + 1, -1 * istride + 2],
[0 * istride + 1, 0 * istride + 2],
[0 * istride + 1, 1 * istride + 2],
[1 * istride + 1, 2 * istride + 2],
[1 * istride + 0, 2 * istride + 1],
[1 * istride + 0, 2 * istride + 0],
[1 * istride + 0, 2 * istride - 1],
];
for i in 0..ysize {
for j in 0..xsize {
let ptr_in = input.offset(i * istride + j);
let x = i32::cast_from(*ptr_in);
let mut sum: i32 = 0;
let mut max = x;
let mut min = x;
for k in 0..2usize {
let cdef_dirs = [
cdef_directions[dir][k],
cdef_directions[(dir + 2) & 7][k],
cdef_directions[(dir + 6) & 7][k],
];
let pri_tap = pri_taps[k];
let p = [
i32::cast_from(*ptr_in.offset(cdef_dirs[0])),
i32::cast_from(*ptr_in.offset(-cdef_dirs[0])),
];
for p_elem in p.iter() {
sum += pri_tap * constrain(*p_elem - x, pri_strength, damping);
if *p_elem != CDEF_VERY_LARGE as i32 {
max = cmp::max(*p_elem, max);
}
min = cmp::min(*p_elem, min);
}
let s = [
i32::cast_from(*ptr_in.offset(cdef_dirs[1])),
i32::cast_from(*ptr_in.offset(-cdef_dirs[1])),
i32::cast_from(*ptr_in.offset(cdef_dirs[2])),
i32::cast_from(*ptr_in.offset(-cdef_dirs[2])),
];
let sec_tap = sec_taps[k];
for s_elem in s.iter() {
if *s_elem != CDEF_VERY_LARGE as i32 {
max = cmp::max(*s_elem, max);
}
min = cmp::min(*s_elem, min);
sum += sec_tap * constrain(*s_elem - x, sec_strength, damping);
}
}
let v = x + ((8 + sum - (sum < 0) as i32) >> 4);
dst[i as usize][j as usize] = T::cast_from(clamp(v, min, max));
}
}
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn check_max_element() {
assert_eq!(first_max_element(&[-1, -1, 1, 2, 3, 4, 6, 6]), (6, 6));
assert_eq!(first_max_element(&[-1, -1, 1, 2, 3, 4, 7, 6]), (6, 7));
assert_eq!(first_max_element(&[0, 0]), (0, 0));
}
}
}
// We use the variance of an 8x8 block to adjust the effective filter strength.
#[inline]
fn adjust_strength(strength: i32, var: i32) -> i32 {
let i = if (var >> 6) != 0 { cmp::min(msb(var >> 6), 12) } else { 0 };
if var != 0 {
(strength * (4 + i) + 8) >> 4
} else {
0
}
}
#[profiling::function]
pub fn cdef_analyze_superblock_range<T: Pixel>(
fi: &FrameInvariants<T>, in_frame: &Frame<T>, blocks: &TileBlocks<'_>,
sb_w: usize, sb_h: usize,
) -> Vec<CdefDirections> {
let mut ret = Vec::<CdefDirections>::with_capacity(sb_h * sb_w);
for sby in 0..sb_h {
for sbx in 0..sb_w {
let sbo = TileSuperBlockOffset(SuperBlockOffset { x: sbx, y: sby });
ret.push(cdef_analyze_superblock(fi, in_frame, blocks, sbo));
}
}
ret
}
#[profiling::function]
pub fn cdef_analyze_superblock<T: Pixel>(
fi: &FrameInvariants<T>, in_frame: &Frame<T>, blocks: &TileBlocks<'_>,
sbo: TileSuperBlockOffset,
) -> CdefDirections {
let coeff_shift = fi.sequence.bit_depth - 8;
let mut dir: CdefDirections =
CdefDirections { dir: [[0; 8]; 8], var: [[0; 8]; 8] };
// Each direction block is 8x8 in y, and direction computation only looks at y
for by in 0..8 {
for bx in 0..8 {
let block_offset = sbo.block_offset(bx << 1, by << 1);
if block_offset.0.x < blocks.cols() && block_offset.0.y < blocks.rows() {
let skip = blocks[block_offset].skip
& blocks[sbo.block_offset(2 * bx + 1, 2 * by)].skip
& blocks[sbo.block_offset(2 * bx, 2 * by + 1)].skip
& blocks[sbo.block_offset(2 * bx + 1, 2 * by + 1)].skip;
if !skip {
let mut var: u32 = 0;
let in_plane = &in_frame.planes[0];
let in_po = sbo.plane_offset(&in_plane.cfg);
let in_slice = in_plane.slice(in_po);
dir.dir[bx][by] = cdef_find_dir::<T>(
&in_slice.reslice(8 * bx as isize, 8 * by as isize),
&mut var,
coeff_shift,
fi.cpu_feature_level,
) as u8;
dir.var[bx][by] = var as i32;
}
}
}
}
dir
}
// input: A Frame of reconstructed/deblocked pixels prepared to
// undergo CDEF. Note that the input is a Frame and not a Tile due to
// Tiles not allowing [supervised] out-of-rect access for padding
// pixels. This will be corrected at some point in the future.
// tile_sbo: specifies an offset into the output Tile, not an
// absolute offset in the visible frame. The Tile's own offset is
// added to this in order to address into the input Frame.
// tb: the TileBlocks associated with the filtered region; the
// provided blocks co-locate with the output region. The TileBlocks
// provide by-[super]qblock CDEF parameters.
// output: TileMut destination for filtered pixels. The output's
// rect specifies the region of the input to be processed (x and y
// are relative to the input Frame's origin). Note that an
// additional area of 2 pixels of padding is used for CDEF. When
// these pixels are unavailable (beyond the visible frame or at a
// tile boundary), the filtering process ignores input pixels that
// don't exist.
/// # Panics
///
/// - If called with invalid parameters
#[profiling::function]
pub fn cdef_filter_superblock<T: Pixel>(
fi: &FrameInvariants<T>, input: &Frame<T>, output: &mut TileMut<'_, T>,
blocks: &TileBlocks<'_>, tile_sbo: TileSuperBlockOffset, cdef_index: u8,
cdef_dirs: &CdefDirections,
) {
let bit_depth = fi.sequence.bit_depth;
let coeff_shift = fi.sequence.bit_depth as i32 - 8;
let cdef_damping = fi.cdef_damping as i32;
let cdef_y_strength = fi.cdef_y_strengths[cdef_index as usize];
let cdef_uv_strength = fi.cdef_uv_strengths[cdef_index as usize];
let cdef_pri_y_strength = (cdef_y_strength / CDEF_SEC_STRENGTHS) as i32;
let mut cdef_sec_y_strength = (cdef_y_strength % CDEF_SEC_STRENGTHS) as i32;
let cdef_pri_uv_strength = (cdef_uv_strength / CDEF_SEC_STRENGTHS) as i32;
let planes = if fi.sequence.chroma_sampling == Cs400 { 1 } else { 3 };
let mut cdef_sec_uv_strength =
(cdef_uv_strength % CDEF_SEC_STRENGTHS) as i32;
if cdef_sec_y_strength == 3 {
cdef_sec_y_strength += 1;
}
if cdef_sec_uv_strength == 3 {
cdef_sec_uv_strength += 1;
}
let tile_rect = *output.planes[0].rect();
let input_xoffset =
tile_rect.x + tile_sbo.plane_offset(&input.planes[0].cfg).x;
let input_yoffset =
tile_rect.y + tile_sbo.plane_offset(&input.planes[0].cfg).y;
let input_xavail = input.planes[0].cfg.width as isize - input_xoffset;
let input_yavail = input.planes[0].cfg.height as isize - input_yoffset;
/* determine what edge padding we have, and what padding we don't.
* We don't pad here, but rather tell the filter_block call what it
* needs to do, then let it handle the specifics (following dav1d's
* lead). We make one assumption that's not obvious: Because the
* cdef clipping area is rounded up to an even 8x8 luma block, we
* don't need to guard against having only one (as opposed to two)
* pixels of padding past the current block boundary. The padding
* is all-or-nothing. */
// Slightly harder than in dav1d; we're not always doing full-frame.
let have_top_p =
if tile_sbo.0.y as isize + tile_rect.y > 0 { CDEF_HAVE_TOP } else { 0 };
let have_left_p =
if tile_sbo.0.x as isize + tile_rect.x > 0 { CDEF_HAVE_LEFT } else { 0 };
let mut edges = have_top_p | CDEF_HAVE_BOTTOM;
// Each direction block is 8x8 in y, potentially smaller if subsampled in chroma
for by in 0..8usize {
if by + 1 >= (input_yavail as usize >> 3) {
edges &= !CDEF_HAVE_BOTTOM
};
edges &= !CDEF_HAVE_LEFT;
edges |= have_left_p;
edges |= CDEF_HAVE_RIGHT;
for bx in 0..8usize {
if bx + 1 >= (input_xavail as usize >> 3) {
edges &= !CDEF_HAVE_RIGHT
};
let block_offset = tile_sbo.block_offset(bx << 1, by << 1);
if block_offset.0.x < blocks.cols() && block_offset.0.y < blocks.rows() {
let skip = blocks[block_offset].skip
& blocks[tile_sbo.block_offset(2 * bx + 1, 2 * by)].skip
& blocks[tile_sbo.block_offset(2 * bx, 2 * by + 1)].skip
& blocks[tile_sbo.block_offset(2 * bx + 1, 2 * by + 1)].skip;
let dir = cdef_dirs.dir[bx][by];
let var = cdef_dirs.var[bx][by];
for p in 0..planes {
let out_plane = &mut output.planes[p];
let in_plane = &input.planes[p];
let xdec = in_plane.cfg.xdec;
let ydec = in_plane.cfg.ydec;
let xsize = 8 >> xdec;
let ysize = 8 >> ydec;
let in_po = PlaneOffset {
x: (input_xoffset >> xdec) + (bx * xsize) as isize,
y: (input_yoffset >> ydec) + (by * ysize) as isize,
};
let in_stride = in_plane.cfg.stride;
let in_slice = &in_plane.slice(in_po);
let out_block = &mut out_plane.subregion_mut(Area::BlockRect {
bo: tile_sbo.block_offset(2 * bx, 2 * by).0,
width: xsize,
height: ysize,
});
if !skip {
let local_pri_strength;
let local_sec_strength;
let mut local_damping: i32 = cdef_damping + coeff_shift;
// See `Cdef_Uv_Dir` constant lookup table in Section 7.15.1
// <https://aomediacodec.github.io/av1-spec/#cdef-block-process>
let local_dir = if p == 0 {
local_pri_strength =
adjust_strength(cdef_pri_y_strength << coeff_shift, var);
local_sec_strength = cdef_sec_y_strength << coeff_shift;
if cdef_pri_y_strength != 0 {
dir as usize
} else {
0
}
} else {
local_pri_strength = cdef_pri_uv_strength << coeff_shift;
local_sec_strength = cdef_sec_uv_strength << coeff_shift;
local_damping -= 1;
if cdef_pri_uv_strength != 0 {
if xdec != ydec {
[7, 0, 2, 4, 5, 6, 6, 6][dir as usize]
} else {
dir as usize
}
} else {
0
}
};
// SAFETY: `cdef_filter_block` may call Assembly code.
// The asserts here verify that we are not calling it
// with invalid parameters.
unsafe {
assert!(
input.planes[p].cfg.width as isize
>= in_po.x
+ xsize as isize
+ if edges & CDEF_HAVE_RIGHT > 0 { 2 } else { 0 }
);
assert!(
0 <= in_po.x - if edges & CDEF_HAVE_LEFT > 0 { 2 } else { 0 }
);
assert!(
input.planes[p].cfg.height as isize
>= in_po.y
+ ysize as isize
+ if edges & CDEF_HAVE_BOTTOM > 0 { 2 } else { 0 }
);
assert!(
0 <= in_po.y - if edges & CDEF_HAVE_TOP > 0 { 2 } else { 0 }
);
cdef_filter_block(
out_block,
in_slice.as_ptr(),
in_stride as isize,
local_pri_strength,
local_sec_strength,
local_dir,
local_damping,
bit_depth,
xdec,
ydec,
edges,
fi.cpu_feature_level,
);
}
} else {
// no filtering, but we need to copy input to output
for i in 0..ysize {
for j in 0..xsize {
out_block[i][j] = in_slice[i][j];
}
}
}
}
}
edges |= CDEF_HAVE_LEFT;
}
edges |= CDEF_HAVE_TOP;
}
}
// The purpose of CDEF is to perform deringing based on the detected
// direction of blocks. CDEF parameters are stored for each 64 by 64
// block of pixels. The CDEF filter is applied on each 8 by 8 block
// of pixels. Reference:
// http://av1-spec.argondesign.com/av1-spec/av1-spec.html#cdef-process
// input: A Frame of reconstructed/deblocked pixels prepared to
// undergo CDEF. cdef_filter_tile acts on a subset of these input
// pixels, as specified by the PlaneRegion rect of the output. Note
// that the input is a Frame and not a Tile due to Tiles not
// allowing [supervised] out-of-rect access for padding pixels.
// This will be corrected at some point in the future.
// tb: the TileBlocks associated with the filtered region; the
// provided blocks co-locate with the output region.
// output: TileMut destination for filtered pixels. The output's
// rect specifies the region of the input to be processed (x and y
// are relative to the input Frame's origin). Note that an
// additional area of 2 pixels of padding is used for CDEF. When
// these pixels are unavailable (beyond the visible frame or at a
// tile boundary), the filtering process ignores input pixels that
// don't exist.
#[profiling::function]
pub fn cdef_filter_tile<T: Pixel>(
fi: &FrameInvariants<T>, input: &Frame<T>, tb: &TileBlocks,
output: &mut TileMut<'_, T>,
) {
// Each filter block is 64x64, except right and/or bottom for non-multiple-of-64 sizes.
// FIXME: 128x128 SB support will break this, we need FilterBlockOffset etc.
// No need to guard against having fewer actual coded blocks than
// the output.rect() area. Inner code already guards this case.
let fb_width = (output.planes[0].rect().width + 63) / 64;
let fb_height = (output.planes[0].rect().height + 63) / 64;
// should parallelize this
for fby in 0..fb_height {
for fbx in 0..fb_width {
// tile_sbo is treated as an offset into the Tiles' plane
// regions, not as an absolute offset in the visible frame. The
// Tile's own offset is added to this in order to address into
// the input Frame.
let tile_sbo = TileSuperBlockOffset(SuperBlockOffset { x: fbx, y: fby });
let cdef_index = tb.get_cdef(tile_sbo);
let cdef_dirs = cdef_analyze_superblock(fi, input, tb, tile_sbo);
cdef_filter_superblock(
fi, input, output, tb, tile_sbo, cdef_index, &cdef_dirs,
);
}
}
}