+++ /dev/null
-//! Discrete 1-D cosine and sine transforms.
-use std::f32::consts;
-
-/// A list of DCT and DST modes.
-#[allow(non_camel_case_types)]
-#[derive(Clone,Copy,Debug,PartialEq)]
-pub enum DCTMode {
- DCT_I,
- DCT_II,
- DCT_III,
- DCT_IV,
- DST_I,
- DST_II,
- DST_III,
- DST_IV,
-}
-
-/// DCT/DST working context.
-#[allow(dead_code)]
-pub struct DCT {
- tmp: Vec<f32>,
- tab: Vec<f32>,
- swaps: Vec<usize>,
- perms: Vec<usize>,
- mode: DCTMode,
- size: usize,
- is_pow2: bool,
- perm_tab: Vec<usize>,
-}
-
-impl DCT {
- /// Constructs a new context for the selected DCT or DST operation.
- pub fn new(mode: DCTMode, size: usize) -> Self {
- let bits = 31 - (size as u32).leading_zeros();
- let is_pow2 = (size & (size - 1)) == 0;
- let mut tmp: Vec<f32>;
- let mut swaps: Vec<usize> = Vec::new();
- let mut perms: Vec<usize>;
- let mut perm_tab: Vec<usize>;
- tmp = Vec::with_capacity(size);
- tmp.resize(size, 0.0);
- if !is_pow2 {
- perms = Vec::new();
- perm_tab = Vec::new();
- } else {
- perms = Vec::with_capacity(size);
- for i in 0..size { perms.push(swp_idx(i, bits)); }
- gen_swaps_for_perm(&mut swaps, &perms);
-
- perm_tab = Vec::with_capacity(size);
- perm_tab.push(0); // padding
- perm_tab.push(0); // size = 1
- perm_tab.push(0); // size = 2
- perm_tab.push(1);
- for blen in 2..=bits {
- let ssize = 1 << blen;
- for i in 0..ssize { perm_tab.push(swp_idx(i, blen)); }
- }
- }
- let mut tab: Vec<f32>;
- match mode {
- DCTMode::DCT_II |
- DCTMode::DST_II |
- DCTMode::DCT_III |
- DCTMode::DST_III |
- DCTMode::DCT_IV => {
- tab = Vec::with_capacity(size * 2);
- tab.push(1.0); // padding
- tab.push(0.0);
- tab.push((consts::PI / 8.0).sin()); // size = 1
- tab.push((consts::PI / 8.0).cos());
- if bits > 1 {
- for blen in 1..=bits {
- let tsize = 1 << blen;
- let base = consts::PI / ((tsize * 8) as f32);
- for i in 0..tsize {
- let phi = ((i * 2 + 1) as f32) * base;
- tab.push(phi.sin());
- tab.push(phi.cos());
- }
- }
- }
- },
-/* DCTMode::DST_IV => {
- },*/
- _ => { tab = Vec::new(); },
- };
-
- Self { tmp, tab, mode, size, swaps, perms, is_pow2, perm_tab }
- }
- fn can_do_fast(&mut self) -> bool {
- if !self.is_pow2 { return false; }
- match self.mode {
- DCTMode::DCT_I | DCTMode::DST_I | DCTMode::DST_IV => false,
- _ => true,
- }
- }
- fn inplace_fast_dct(&mut self, dst: &mut [f32]) {
- match self.mode {
- DCTMode::DCT_II => {
- dct_II_inplace(dst, self.size, 1, &self.tab, &self.perm_tab);
- },
- DCTMode::DST_II => {
- dst_II_inplace(dst, self.size, 1, &self.tab, &self.perm_tab);
- },
- DCTMode::DCT_III => {
- dct_III_inplace(dst, self.size, 1, &self.tab, &self.perm_tab);
- },
- DCTMode::DST_III => {
- dst_III_inplace(dst, self.size, 1, &self.tab, &self.perm_tab);
- },
- DCTMode::DCT_IV => {
- dct_IV_inplace(dst, self.size, 1, &self.tab, &self.perm_tab);
- },
- _ => unreachable!(),
- };
- }
- /// Performs DCT/DST.
- pub fn do_dct(&mut self, src: &[f32], dst: &mut [f32]) {
- if self.can_do_fast() {
- for (i, ni) in self.perms.iter().enumerate() { dst[i] = src[*ni]; }
- self.inplace_fast_dct(dst);
- } else {
- do_ref_dct(self.mode, src, dst, self.size);
- }
- }
- /// Performs inplace DCT/DST.
- pub fn do_dct_inplace(&mut self, buf: &mut [f32]) {
- if self.can_do_fast() {
- swap_buf(buf, &self.swaps);
- self.inplace_fast_dct(buf);
- } else {
- self.tmp.copy_from_slice(&buf[0..self.size]);
- do_ref_dct(self.mode, &self.tmp, buf, self.size);
- }
- }
- /// Returns the scale for output normalisation.
- pub fn get_scale(&self) -> f32 {
- let fsize = self.size as f32;
- match self.mode {
- DCTMode::DCT_I => 2.0 / (fsize - 1.0),
- DCTMode::DST_I => 2.0 / (fsize + 1.0),
- DCTMode::DCT_II => 1.0,
- DCTMode::DCT_III=> 1.0,
- DCTMode::DST_II => 1.0,
- DCTMode::DST_III=> 1.0,
- DCTMode::DCT_IV => 1.0,
- _ => 2.0 / fsize,
- }
- }
-}
-
-fn reverse_bits(inval: u32) -> u32 {
- const REV_TAB: [u8; 16] = [
- 0b0000, 0b1000, 0b0100, 0b1100, 0b0010, 0b1010, 0b0110, 0b1110,
- 0b0001, 0b1001, 0b0101, 0b1101, 0b0011, 0b1011, 0b0111, 0b1111,
- ];
-
- let mut ret = 0;
- let mut val = inval;
- for _ in 0..8 {
- ret = (ret << 4) | (REV_TAB[(val & 0xF) as usize] as u32);
- val >>= 4;
- }
- ret
-}
-
-fn swp_idx(idx: usize, bits: u32) -> usize {
- let s = reverse_bits(idx as u32) as usize;
- s >> (32 - bits)
-}
-
-fn gen_swaps_for_perm(swaps: &mut Vec<usize>, perms: &[usize]) {
- let mut idx_arr: Vec<usize> = Vec::with_capacity(perms.len());
- for i in 0..perms.len() { idx_arr.push(i); }
- let mut run_size = 0;
- let mut run_pos = 0;
- for idx in 0..perms.len() {
- if perms[idx] == idx_arr[idx] {
- if run_size == 0 { run_pos = idx; }
- run_size += 1;
- } else {
- for i in 0..run_size {
- swaps.push(run_pos + i);
- }
- run_size = 0;
- let mut spos = idx + 1;
- while idx_arr[spos] != perms[idx] { spos += 1; }
- idx_arr[spos] = idx_arr[idx];
- idx_arr[idx] = perms[idx];
- swaps.push(spos);
- }
- }
-}
-
-fn swap_buf(buf: &mut [f32], swaps: &[usize]) {
- for (idx, nidx) in swaps.iter().enumerate() {
- if idx != *nidx {
- buf.swap(*nidx, idx);
- }
- }
-}
-
-fn do_ref_dct(mode: DCTMode, src: &[f32], dst: &mut [f32], size: usize) {
- match mode {
- DCTMode::DCT_I => dct_I_ref(src, dst, size),
- DCTMode::DST_I => dst_I_ref(src, dst, size),
- DCTMode::DCT_II => dct_II_ref(src, dst, size),
- DCTMode::DST_II => dst_II_ref(src, dst, size),
- DCTMode::DCT_III => dct_III_ref(src, dst, size),
- DCTMode::DST_III => dst_III_ref(src, dst, size),
- DCTMode::DCT_IV => dct_IV_ref(src, dst, size),
- DCTMode::DST_IV => dst_IV_ref(src, dst, size),
- };
-}
-
-#[allow(non_snake_case)]
-fn dct_I_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / ((size - 1) as f32);
- for k in 0..size {
- let mut sum = (src[0] + (if (k & 1) != 0 { -src[size - 1] } else { src[size - 1] })) * 0.5;
- for n in 1..size-1 {
- sum += src[n] * (base * ((n * k) as f32)).cos();
- }
- dst[k] = sum;
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_I_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / ((size + 1) as f32);
- for k in 0..size {
- let mut sum = 0.0;
- for n in 0..size {
- sum += src[n] * (base * (((n + 1) * (k + 1)) as f32)).sin();
- }
- dst[k] = sum;
- }
-}
-
-#[allow(non_snake_case)]
-fn dct_II_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = 0.0;
- for n in 0..size {
- sum += src[n] * (base * ((n as f32) + 0.5) * (k as f32)).cos();
- }
- dst[k] = sum * (if k == 0 { (1.0 / (size as f32)).sqrt() } else { (2.0 / (size as f32)).sqrt() });
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_II_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = 0.0;
- let kmod = (k + 1) as f32;
- for n in 0..size {
- sum += src[n] * (base * ((n as f32) + 0.5) * kmod).sin();
- }
- dst[k] = sum * (2.0 / (size as f32)).sqrt();
- }
- dst[size - 1] /= consts::SQRT_2;
-}
-
-#[allow(non_snake_case)]
-fn dct_III_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = src[0] / consts::SQRT_2;
- let kmod = (k as f32) + 0.5;
- for n in 1..size {
- sum += src[n] * (base * (n as f32) * kmod).cos();
- }
- dst[k] = sum * (2.0 / (size as f32)).sqrt();
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_III_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = 0.0;
- let kmod = (k as f32) + 0.5;
- for n in 0..size-1 {
- sum += src[n] * (base * ((n + 1) as f32) * kmod).sin();
- }
- sum += src[size - 1] / consts::SQRT_2 * (base * (size as f32) * kmod).sin();
- dst[k] = sum * (2.0 / (size as f32)).sqrt();
- }
-}
-
-#[allow(non_snake_case)]
-fn dct_IV_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = 0.0;
- let kmod = (k as f32) + 0.5;
- for n in 0..size {
- sum += src[n] * (base * ((n as f32) + 0.5) * kmod).cos();
- }
- dst[k] = sum;
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_IV_ref(src: &[f32], dst: &mut [f32], size: usize) {
- let base = consts::PI / (size as f32);
- for k in 0..size {
- let mut sum = 0.0;
- let kmod = (k as f32) + 0.5;
- for n in 0..size {
- sum += src[n] * (base * ((n as f32) + 0.5) * kmod).sin();
- }
- dst[k] = sum;
- }
-}
-
-const DCT_II_C0: f32 = 0.65328148243818826393; // cos(1*PI/8) / sqrt(2)
-const DCT_II_C1: f32 = 0.27059805007309849220; // cos(3*PI/8) / sqrt(2)
-
-#[allow(non_snake_case)]
-fn dct_II_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- match size {
- 0 | 1 => {},
- 2 => {
- let i0 = buf[0];
- let i1 = buf[step];
- buf[0] = (i0 + i1) / consts::SQRT_2;
- buf[step] = (i0 - i1) / consts::SQRT_2;
- },
- 4 => {
- let i0 = buf[0 * step];
- let i1 = buf[2 * step];
- let i2 = buf[1 * step];
- let i3 = buf[3 * step];
- let t0 = (i0 + i3) * 0.5;
- let t1 = (i1 + i2) * 0.5;
- buf[0 * step] = t0 + t1;
- buf[2 * step] = t0 - t1;
- let t0 = i0 - i3;
- let t1 = i1 - i2;
- buf[1 * step] = DCT_II_C0 * t0 + DCT_II_C1 * t1;
- buf[3 * step] = DCT_II_C1 * t0 - DCT_II_C0 * t1;
- },
- _ => {
- let hsize = size >> 1;
- for i in 0..hsize {
- let i0 = buf[i * step];
- let i1 = buf[(size - 1 - i) * step];
- if (i & 1) == 0 {
- buf[i * step] = (i0 + i1) / consts::SQRT_2;
- buf[(size - 1 - i) * step] = (i0 - i1) / consts::SQRT_2;
- } else {
- buf[i * step] = (i1 - i0) / consts::SQRT_2;
- buf[(size - 1 - i) * step] = (i1 + i0) / consts::SQRT_2;
- }
- }
- dct_II_inplace(buf, hsize, step * 2, tab, perm_tab);
- dct_II_part2_inplace(&mut buf[step..], hsize, step * 2, tab, perm_tab);
- },
- };
-}
-
-#[allow(non_snake_case)]
-fn dct_II_part2_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- let hsize = size >> 1;
-// todo optimise for size = 4
- for i in 0..hsize {
- let i0 = buf[perm_tab[size + i] * step];
- let i1 = buf[perm_tab[size + size - i - 1] * step];
- let c0 = tab[size + i * 2 + 0];
- let c1 = tab[size + i * 2 + 1];
- buf[perm_tab[size + i] * step] = c0 * i0 + c1 * i1;
- buf[perm_tab[size + size - i - 1] * step] = c0 * i1 - c1 * i0;
- }
-
- dct_II_inplace(buf, hsize, step * 2, tab, perm_tab);
- dst_II_inplace(&mut buf[step..], hsize, step * 2, tab, perm_tab);
-
- buf[(size - 1) * step] = -buf[(size - 1) * step];
- for i in 1..hsize {
- let (i0, i1) = if (i & 1) == 0 {
- (buf[i * step * 2], -buf[i * step * 2 - step])
- } else {
- (buf[i * step * 2], buf[i * step * 2 - step])
- };
- buf[i * step * 2 - step] = (i0 + i1) / consts::SQRT_2;
- buf[i * step * 2] = (i0 - i1) / consts::SQRT_2;
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_II_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- if size <= 1 { return; }
- let hsize = size >> 1;
- for i in hsize..size { buf[i * step] = -buf[i * step]; }
- dct_II_inplace(buf, size, step, tab, perm_tab);
- for i in 0..hsize {
- let idx0 = i * step;
- let idx1 = (size - 1 - i) * step;
- buf.swap(idx0, idx1);
- }
-}
-
-#[allow(non_snake_case)]
-fn dct_III_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- if size <= 1 { return; }
- let hsize = size >> 1;
- dct_III_inplace(buf, hsize, step, tab, perm_tab);
- dct_IV_inplace(&mut buf[step*hsize..], hsize, step, tab, perm_tab);
- for i in 0..(size >> 2) {
- buf.swap((size - 1 - i) * step, (hsize + i) * step);
- }
- for i in 0..hsize {
- let i0 = buf[i * step] / consts::SQRT_2;
- let i1 = buf[(size-i-1) * step] / consts::SQRT_2;
- buf[i * step] = i0 + i1;
- buf[(size-i-1) * step] = i0 - i1;
- }
-}
-
-#[allow(non_snake_case)]
-fn dst_III_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- if size <= 1 { return; }
- let hsize = size >> 1;
- for i in 0..hsize {
- let idx0 = i * step;
- let idx1 = (size - 1 - i) * step;
- buf.swap(idx0, idx1);
- }
- dct_III_inplace(buf, size, step, tab, perm_tab);
- for i in 0..hsize { buf[i * 2 * step + step] = -buf[i * 2 * step + step]; }
-}
-
-#[allow(non_snake_case)]
-fn dct_IV_inplace(buf: &mut [f32], size: usize, step: usize, tab: &[f32], perm_tab: &[usize]) {
- if size <= 1 { return; }
- let hsize = size >> 1;
-
- for i in 0..hsize {
- let idx0 = perm_tab[size + i];
- let idx1 = size - 1 - idx0;
- let i0 = buf[idx0 * step];
- let i1 = buf[idx1 * step];
- let c0 = tab[size + i * 2 + 1];
- let c1 = tab[size + i * 2 + 0];
- buf[idx0 * step] = c0 * i0 + c1 * i1;
- buf[idx1 * step] = c0 * i1 - c1 * i0;
- }
- for i in (hsize+1..size).step_by(2) {
- buf[i] = -buf[i];
- }
- dct_II_inplace(buf, hsize, step * 2, tab, perm_tab);
- dct_II_inplace(&mut buf[step..], hsize, step * 2, tab, perm_tab);
- for i in 0..(size >> 2) {
- buf.swap((size - 1 - i * 2) * step, (i * 2 + 1) * step);
- }
- for i in (3..size).step_by(4) {
- buf[i] = -buf[i];
- }
- buf[0] *= consts::SQRT_2;
- buf[(size - 1) * step] *= -consts::SQRT_2;
- for i in 0..hsize-1 {
- let i0 = buf[(i * 2 + 2) * step];
- let i1 = buf[(i * 2 + 1) * step];
- buf[(i * 2 + 2) * step] = i0 + i1;
- buf[(i * 2 + 1) * step] = i0 - i1;
- }
- for i in 0..size {
- buf[i * step] /= consts::SQRT_2;
- }
-}
-
-#[cfg(test)]
-mod test {
- use super::*;
-
- fn test_pair(mode: DCTMode, invmode: DCTMode, size: usize) {
- println!("testing {:?} -> {:?}", mode, invmode);
- let mut fin: Vec<f32> = Vec::with_capacity(size);
- let mut out: Vec<f32> = Vec::with_capacity(size);
- out.resize(size, 0.0);
- let mut seed: u32 = 42;
- for _ in 0..size {
- seed = seed.wrapping_mul(1664525).wrapping_add(1013904223);
- let val = (seed >> 16) as i16;
- fin.push((val as f32) / 256.0);
- }
- let mut dct = DCT::new(mode, size);
- dct.do_dct(&fin, &mut out);
- let mut dct = DCT::new(invmode, size);
- dct.do_dct_inplace(&mut out);
-
- let scale = dct.get_scale();
- for i in 0..fin.len() {
- assert!((fin[i] - out[i]*scale).abs() < 1.0e-2);
- }
- }
- #[test]
- fn test_dct() {
- test_pair(DCTMode::DCT_I, DCTMode::DCT_I, 32);
- test_pair(DCTMode::DST_I, DCTMode::DST_I, 32);
- test_pair(DCTMode::DCT_II, DCTMode::DCT_III, 32);
- test_pair(DCTMode::DST_II, DCTMode::DST_III, 32);
- test_pair(DCTMode::DCT_III, DCTMode::DCT_II, 32);
- test_pair(DCTMode::DST_III, DCTMode::DST_II, 32);
- test_pair(DCTMode::DCT_IV, DCTMode::DCT_IV, 32);
- test_pair(DCTMode::DST_IV, DCTMode::DST_IV, 32);
- }
-}
projects / nihav.git / blobdiff