projects / nihav.git / blame
| Commit | Line | Data |
|---|---|---|
| f1f6f4aa KS |
1 | use std::f32::consts; |
| 2 | use super::fft::*; | |
| 3 | ||
| 4 | pub struct IMDCT { | |
| 5 | twiddle: Vec<FFTComplex>, | |
| 6 | fft: FFT, | |
| 7 | size: usize, | |
| 8 | z: Vec<FFTComplex>, | |
| 9 | } | |
| 10 | ||
| 11 | /* | |
| 12 | fn imdct(src: &[f32], dst: &mut [f32], length: usize) { | |
| 13 | for n in 0..length*2 { | |
| 14 | dst[n] = 0.0; | |
| 15 | for k in 0..length { | |
| 16 | dst[n] += src[k] * (consts::PI / (length as f32) * ((n as f32) + 0.5 + ((length/2) as f32)) * ((k as f32) + 0.5)).cos(); | |
| 17 | } | |
| 18 | } | |
| 19 | }*/ | |
| 20 | ||
| 21 | impl IMDCT { | |
| 9e78289c | 22 | pub fn new(size: usize, scaledown: bool) -> Self { |
| f1f6f4aa KS |
23 | let mut twiddle: Vec<FFTComplex> = Vec::with_capacity(size / 4); |
| 24 | let factor = 2.0 * consts::PI / ((8 * size) as f32); | |
| 8cb5b63b | 25 | let scale = if scaledown { (1.0 / (size as f32)).sqrt() } else { 1.0 }; |
| f1f6f4aa | 26 | for k in 0..size/4 { |
| 8cb5b63b | 27 | twiddle.push(FFTComplex::exp(factor * ((8 * k + 1) as f32)).scale(scale)); |
| f1f6f4aa | 28 | } |
| 9e78289c | 29 | let fft = FFTBuilder::new_fft(size/4, false); |
| f1f6f4aa KS |
30 | let mut z: Vec<FFTComplex> = Vec::with_capacity(size / 2); |
| 31 | z.resize(size / 2, FFTC_ZERO); | |
| 32 | IMDCT { twiddle, fft, size, z } | |
| 33 | } | |
| 34 | pub fn imdct(&mut self, src: &[f32], dst: &mut [f32]) { | |
| 35 | let size2 = self.size / 2; | |
| 36 | let size4 = self.size / 4; | |
| 37 | let size8 = self.size / 8; | |
| 38 | for k in 0..size4 { | |
| 39 | let c = FFTComplex { re: src[size2 - 2 * k - 1], im: src[ 2 * k] }; | |
| 40 | self.z[k] = c * self.twiddle[k]; | |
| 41 | } | |
| 9e78289c | 42 | self.fft.do_ifft_inplace(&mut self.z); |
| f1f6f4aa KS |
43 | for k in 0..size4 { |
| 44 | self.z[k] *= self.twiddle[k]; | |
| 45 | } | |
| 46 | for n in 0..size8 { | |
| 47 | dst[ 2 * n] = -self.z[size8 + n] .im; | |
| 48 | dst[ 2 * n + 1] = self.z[size8 - n - 1].re; | |
| 49 | dst[ size4 + 2 * n] = -self.z[ n] .re; | |
| 50 | dst[ size4 + 2 * n + 1] = self.z[size4 - n - 1].im; | |
| 51 | dst[ size2 + 2 * n] = -self.z[size8 + n] .re; | |
| 52 | dst[ size2 + 2 * n + 1] = self.z[size8 - n - 1].im; | |
| 53 | dst[3 * size4 + 2 * n] = self.z[ n] .im; | |
| 54 | dst[3 * size4 + 2 * n + 1] = -self.z[size4 - n - 1].re; | |
| 55 | } | |
| 56 | } | |
| 9e424d2f KS |
57 | pub fn imdct_half(&mut self, src: &[f32], dst: &mut [f32]) { |
| 58 | let size2 = self.size / 2; | |
| 59 | let size4 = self.size / 4; | |
| 60 | let size8 = self.size / 8; | |
| 61 | for k in 0..size4 { | |
| 62 | let c = FFTComplex { re: src[size2 - 2 * k - 1], im: src[ 2 * k] }; | |
| 63 | self.z[k] = c * self.twiddle[k]; | |
| 64 | } | |
| 65 | self.fft.do_ifft_inplace(&mut self.z); | |
| 66 | for k in 0..size4 { | |
| 67 | self.z[k] *= self.twiddle[k]; | |
| 68 | } | |
| 69 | for n in 0..size8 { | |
| 70 | dst[ 2 * n] = -self.z[ n] .re; | |
| 71 | dst[ 2 * n + 1] = self.z[size4 - n - 1].im; | |
| 72 | dst[size4 + 2 * n] = -self.z[size8 + n] .re; | |
| 73 | dst[size4 + 2 * n + 1] = self.z[size8 - n - 1].im; | |
| 74 | } | |
| 75 | } | |
| f1f6f4aa | 76 | } |