67 lines
1.9 KiB
Rust
67 lines
1.9 KiB
Rust
use crate::{constants::TILE_SZ2, quality_settings::{self, QualitySettings}};
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const ZIGZAG: [u8; TILE_SZ2] = [
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0 , 1 , 5 , 6 , 14, 15, 27, 28,
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2 , 4 , 7 , 13, 16, 26, 29, 42,
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3 , 8 , 12, 17, 25, 30, 41, 43,
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9 , 11, 18, 24, 31, 40, 44, 53,
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10, 19, 23, 32, 39, 45, 52, 54,
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20, 22, 33, 38, 46, 51, 55, 60,
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21, 34, 37, 47, 50, 56, 59, 61,
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35, 36, 48, 49, 57, 58, 62, 63,
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];
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pub fn to_quantized(
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quality_settings: QualitySettings,
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coefs: [i16; TILE_SZ2]
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) -> [i16; TILE_SZ2] {
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let mut quant: [i16; TILE_SZ2] = [0; TILE_SZ2];
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for cf_ix in 0..TILE_SZ2 {
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let div = divisor(quality_settings, cf_ix);
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let qval = (coefs[cf_ix] + div / 2) / div;
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quant[ZIGZAG[cf_ix] as usize] = qval
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}
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let mut indices = [0; TILE_SZ2];
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for i in 0..indices.len() {
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indices[i] = i;
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}
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indices.sort_by_key(|i| -quant[*i].abs());
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for i in (quality_settings.values[quality_settings::QUANTIZATION_N_QUANTS_TO_KEEP] as usize)..indices.len() {
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quant[indices[i]] = 0;
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}
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quant
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}
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pub fn from_quantized(
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quality_settings: QualitySettings,
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quant: [i16; TILE_SZ2]
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) -> [i16; TILE_SZ2] {
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let mut coefs: [i16; TILE_SZ2] = [0; TILE_SZ2];
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for cf_ix in 0..TILE_SZ2 {
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let div = divisor(quality_settings, cf_ix);
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coefs[cf_ix] = quant[ZIGZAG[cf_ix] as usize].wrapping_mul(div);
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}
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coefs
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}
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pub fn divisor(
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quality_settings: QualitySettings,
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cf_ix: usize
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) -> i16 {
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if cf_ix == 0 { return quality_settings.values[quality_settings::QUANTIZATION_QUANT0_DIVISOR] as i16; }
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let x = cf_ix % 8;
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let y = cf_ix / 8;
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let div =
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(quality_settings.values[quality_settings::QUANTIZATION_CONSTANT] as i16).wrapping_add(
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(x as i16 + y as i16).wrapping_mul(
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quality_settings.values[quality_settings::QUANTIZATION_LINEAR] as i16
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)
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);
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if div==32 && cf_ix != 0 {
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dbg!(cf_ix, x, y, div);
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}
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return div;
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} |