459 lines
18 KiB
Rust
459 lines
18 KiB
Rust
// Spectral Compressor: an FFT based compressor
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// Copyright (C) 2021-2022 Robbert van der Helm
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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use nih_plug::prelude::*;
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use nih_plug_vizia::ViziaState;
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use realfft::num_complex::Complex32;
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use realfft::{ComplexToReal, RealFftPlanner, RealToComplex};
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use std::sync::Arc;
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mod dry_wet_mixer;
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mod editor;
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const MIN_WINDOW_ORDER: usize = 6;
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#[allow(dead_code)]
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const MIN_WINDOW_SIZE: usize = 1 << MIN_WINDOW_ORDER; // 64
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const DEFAULT_WINDOW_ORDER: usize = 12;
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#[allow(dead_code)]
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const DEFAULT_WINDOW_SIZE: usize = 1 << DEFAULT_WINDOW_ORDER; // 4096
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const MAX_WINDOW_ORDER: usize = 15;
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const MAX_WINDOW_SIZE: usize = 1 << MAX_WINDOW_ORDER; // 32768
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const MIN_OVERLAP_ORDER: usize = 2;
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#[allow(dead_code)]
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const MIN_OVERLAP_TIMES: usize = 2 << MIN_OVERLAP_ORDER; // 4
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const DEFAULT_OVERLAP_ORDER: usize = 3;
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#[allow(dead_code)]
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const DEFAULT_OVERLAP_TIMES: usize = 1 << DEFAULT_OVERLAP_ORDER; // 4
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const MAX_OVERLAP_ORDER: usize = 5;
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#[allow(dead_code)]
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const MAX_OVERLAP_TIMES: usize = 1 << MAX_OVERLAP_ORDER; // 32
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/// This is a port of <https://github.com/robbert-vdh/spectral-compressor/>.
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struct SpectralCompressor {
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params: Arc<SpectralCompressorParams>,
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editor_state: Arc<ViziaState>,
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/// An adapter that performs most of the overlap-add algorithm for us.
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stft: util::StftHelper,
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/// Contains a Hann window function of the current window length, passed to the overlap-add
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/// helper. Allocated with a `MAX_WINDOW_SIZE` initial capacity.
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window_function: Vec<f32>,
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/// A mixer to mix the dry signal back into the processed signal with latency compensation.
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dry_wet_mixer: dry_wet_mixer::DryWetMixer,
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/// The algorithms for the FFT and IFFT operations, for each supported order so we can switch
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/// between them without replanning or allocations. Initialized during `initialize()`.
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plan_for_order: Option<[Plan; MAX_WINDOW_ORDER - MIN_WINDOW_ORDER + 1]>,
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/// The output of our real->complex FFT.
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complex_fft_buffer: Vec<Complex32>,
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}
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/// An FFT plan for a specific window size, all of which will be precomputed during initilaization.
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struct Plan {
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/// The algorithm for the FFT operation.
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r2c_plan: Arc<dyn RealToComplex<f32>>,
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/// The algorithm for the IFFT operation.
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c2r_plan: Arc<dyn ComplexToReal<f32>>,
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}
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#[derive(Params)]
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struct SpectralCompressorParams {
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/// Gain applied just before the DFT as part of the STFT process.
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#[id = "input_db"]
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input_gain_db: FloatParam,
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/// Makeup gain applied after the IDFT in the STFT process. If automatic makeup gain is enabled,
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/// then this acts as an offset on top of that.
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#[id = "output_db"]
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output_gain_db: FloatParam,
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// TODO: Bring this back, and with values that make more sense
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// /// Try to automatically compensate for gain differences with different input gain, threshold, and ratio values.
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// #[id = "auto_makeup"]
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// auto_makeup_gain: BoolParam,
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/// How much of the dry signal to mix in with the processed signal. The mixing is done after
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/// applying the output gain. In other words, the dry signal is not gained in any way.
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#[id = "dry_wet"]
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dry_wet_ratio: FloatParam,
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/// Sets the 0-20 Hz bin to 0 since this won't have a lot of semantic meaning anymore after this
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/// plugin and it will thus just eat up headroom.
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#[id = "dc_filter"]
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dc_filter: BoolParam,
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// TODO: Custom target curves for the non-sidechained version
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//
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// TODO: Sidechaining
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//
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/// The downwards compression threshold relative to the target curve.
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#[id = "thresh_down_off"]
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downwards_threshold_offset_db: FloatParam,
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#[id = "thresh_up_off"]
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/// The upwards compression threshold relative to the target curve.
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upwards_threshold_offset_db: FloatParam,
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/// The downwards compression ratio. At 1.0 the downwards compressor is disengaged.
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#[id = "ratio_down"]
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downwards_ratio: FloatParam,
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/// The upwards compression ratio. At 1.0 the upwards compressor is disengaged.
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#[id = "ratio_up"]
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upwards_ratio: FloatParam,
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// TODO: High frequency ratio falloff, make the compression milder for higher frequencies to make it less piercing
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/// The compressor's attack time in milliseconds. Controls both upwards and downwards
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/// compression.
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#[id = "attack"]
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compressor_attack_ms: FloatParam,
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/// The compressor's release time in milliseconds. Controls both upwards and downwards
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/// compression.
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#[id = "release"]
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compressor_release_ms: FloatParam,
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}
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impl Default for SpectralCompressor {
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fn default() -> Self {
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Self {
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params: Arc::new(SpectralCompressorParams::default()),
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editor_state: editor::default_state(),
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// These three will be set to the correct values in the initialize function
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stft: util::StftHelper::new(Self::DEFAULT_NUM_OUTPUTS as usize, MAX_WINDOW_SIZE, 0),
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window_function: Vec::with_capacity(MAX_WINDOW_SIZE),
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dry_wet_mixer: dry_wet_mixer::DryWetMixer::new(0, 0, 0),
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// This is initialized later since we don't want to do non-trivial computations before
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// the plugin is initialized
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plan_for_order: None,
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complex_fft_buffer: Vec::with_capacity(MAX_WINDOW_SIZE / 2 + 1),
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}
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}
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}
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impl Default for SpectralCompressorParams {
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fn default() -> Self {
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Self {
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// We don't need any smoothing for these parameters as the overlap-add process will
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// already act as a form of smoothing
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input_gain_db: FloatParam::new(
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"Input Gain",
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0.0,
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FloatRange::Linear {
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min: -50.0,
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max: 50.0,
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},
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)
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.with_unit(" dB")
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.with_step_size(0.1),
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output_gain_db: FloatParam::new(
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"Output Gain",
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0.0,
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FloatRange::Linear {
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min: -50.0,
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max: 50.0,
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},
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)
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.with_unit(" dB")
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.with_step_size(0.1),
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// auto_makeup_gain: BoolParam::new("Auto Makeup Gain", true),
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dry_wet_ratio: FloatParam::new("Mix", 1.0, FloatRange::Linear { min: 0.0, max: 1.0 })
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.with_unit("%")
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.with_smoother(SmoothingStyle::Linear(15.0))
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.with_value_to_string(formatters::v2s_f32_percentage(0))
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.with_string_to_value(formatters::s2v_f32_percentage()),
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dc_filter: BoolParam::new("DC Filter", true),
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// TODO: Set nicer default values for these things
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// As explained above, these offsets are relative to the target curve
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downwards_threshold_offset_db: FloatParam::new(
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"Downwards Offset",
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0.0,
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FloatRange::Linear {
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min: -50.0,
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max: 50.0,
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},
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)
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.with_unit(" dB")
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.with_step_size(0.1),
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upwards_threshold_offset_db: FloatParam::new(
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"Upwards Offset",
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0.0,
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FloatRange::Linear {
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min: -50.0,
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max: 50.0,
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},
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)
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.with_unit(" dB")
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.with_step_size(0.1),
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downwards_ratio: FloatParam::new(
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"Downwards Ratio",
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1.0,
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FloatRange::Skewed {
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min: 1.0,
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max: 300.0,
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factor: FloatRange::skew_factor(-2.0),
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},
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)
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.with_step_size(0.1)
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.with_value_to_string(formatters::v2s_compression_ratio(1))
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.with_string_to_value(formatters::s2v_compression_ratio()),
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upwards_ratio: FloatParam::new(
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"Upwards Ratio",
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1.0,
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FloatRange::Skewed {
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min: 1.0,
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max: 300.0,
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factor: FloatRange::skew_factor(-2.0),
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},
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)
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.with_step_size(0.1)
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.with_value_to_string(formatters::v2s_compression_ratio(1))
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.with_string_to_value(formatters::s2v_compression_ratio()),
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compressor_attack_ms: FloatParam::new(
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"Attack",
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150.0,
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FloatRange::Skewed {
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// TODO: Make sure to handle 0 attack and release times in the compressor
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min: 0.0,
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max: 10_000.0,
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factor: FloatRange::skew_factor(-2.0),
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},
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)
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.with_unit(" ms")
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.with_step_size(0.1),
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compressor_release_ms: FloatParam::new(
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"Release",
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300.0,
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FloatRange::Skewed {
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min: 0.0,
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max: 10_000.0,
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factor: FloatRange::skew_factor(-2.0),
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},
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)
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.with_unit(" ms")
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.with_step_size(0.1),
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}
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}
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}
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impl Plugin for SpectralCompressor {
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const NAME: &'static str = "Spectral Compressor";
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const VENDOR: &'static str = "Robbert van der Helm";
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const URL: &'static str = "https://github.com/robbert-vdh/nih-plug";
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const EMAIL: &'static str = "mail@robbertvanderhelm.nl";
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const VERSION: &'static str = "0.2.0";
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const DEFAULT_NUM_INPUTS: u32 = 2;
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const DEFAULT_NUM_OUTPUTS: u32 = 2;
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const SAMPLE_ACCURATE_AUTOMATION: bool = true;
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fn params(&self) -> Arc<dyn Params> {
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self.params.clone()
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}
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fn editor(&self) -> Option<Box<dyn Editor>> {
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editor::create(self.params.clone(), self.editor_state.clone())
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}
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fn accepts_bus_config(&self, config: &BusConfig) -> bool {
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// We can support any channel layout
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config.num_input_channels == config.num_output_channels && config.num_input_channels > 0
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}
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fn initialize(
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&mut self,
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bus_config: &BusConfig,
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buffer_config: &BufferConfig,
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context: &mut impl InitContext,
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) -> bool {
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// This plugin can accept any number of channels, so we need to resize channel-dependent
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// data structures accordinly
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if self.stft.num_channels() != bus_config.num_output_channels as usize {
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self.stft = util::StftHelper::new(self.stft.num_channels(), MAX_WINDOW_SIZE, 0);
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}
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self.dry_wet_mixer.resize(
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bus_config.num_output_channels as usize,
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buffer_config.max_buffer_size as usize,
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MAX_WINDOW_SIZE,
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);
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// Planning with RustFFT is very fast, but it will still allocate we we'll plan all of the
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// FFTs we might need in advance
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if self.plan_for_order.is_none() {
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let mut planner = RealFftPlanner::new();
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let plan_for_order: Vec<Plan> = (MIN_WINDOW_ORDER..=MAX_WINDOW_ORDER)
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.map(|order| Plan {
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r2c_plan: planner.plan_fft_forward(1 << order),
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c2r_plan: planner.plan_fft_inverse(1 << order),
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})
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.collect();
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self.plan_for_order = Some(
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plan_for_order
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.try_into()
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.unwrap_or_else(|_| panic!("Mismatched plan orders")),
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);
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}
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// TODO: Fetch from a parameter
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let window_size = DEFAULT_WINDOW_SIZE;
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self.resize_for_window(window_size);
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context.set_latency_samples(self.stft.latency_samples());
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true
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}
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fn reset(&mut self) {
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self.dry_wet_mixer.reset();
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}
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fn process(
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&mut self,
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buffer: &mut Buffer,
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_aux: &mut AuxiliaryBuffers,
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context: &mut impl ProcessContext,
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) -> ProcessStatus {
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// If the window size has changed since the last process call, reset the buffers and chance
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// our latency. All of these buffers already have enough capacity so this won't allocate.
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// TODO: Fetch from a parameter
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let overlap_times = DEFAULT_OVERLAP_TIMES;
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// TODO: Fetch from a parameter
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let window_size = DEFAULT_WINDOW_SIZE;
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if self.window_function.len() != window_size {
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self.resize_for_window(window_size);
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context.set_latency_samples(self.stft.latency_samples());
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}
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// These plans have already been made during initialization we can switch between versions
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// without reallocating
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let fft_plan = &mut self.plan_for_order.as_mut().unwrap()
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// FIXME: Use the parameter
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// [self.params.window_size_order.value as usize - MIN_WINDOW_ORDER];
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[DEFAULT_WINDOW_ORDER - MIN_WINDOW_ORDER];
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let num_bins = self.complex_fft_buffer.len();
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let sample_rate = context.transport().sample_rate;
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// The overlap gain compensation is based on a squared Hann window, which will sum perfectly
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// at four times overlap or higher. We'll apply a regular Hann window before the analysis
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// and after the synthesis.
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let gain_compensation: f32 =
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((overlap_times as f32 / 4.0) * 1.5).recip() / window_size as f32;
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// We'll apply the square root of the total gain compensation at the DFT and the IDFT
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// stages. That way the compressor threshold values make much more sense.
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let input_gain =
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util::db_to_gain(self.params.input_gain_db.value) * gain_compensation.sqrt();
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let output_gain =
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util::db_to_gain(self.params.output_gain_db.value) * gain_compensation.sqrt();
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// TODO: Auto makeup gain
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// This is mixed in later with latency compensation applied
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self.dry_wet_mixer.write_dry(buffer);
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self.stft
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.process_overlap_add(buffer, overlap_times, |_channel_idx, real_fft_buffer| {
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// We'll window the input with a Hann function to avoid spectral leakage. The input
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// gain here also contains a compensation factor for the forward FFT to make the
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// compressor thresholds make more sense.
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for (sample, window_sample) in real_fft_buffer.iter_mut().zip(&self.window_function)
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{
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*sample *= window_sample * input_gain;
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}
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// RustFFT doesn't actually need a scratch buffer here, so we'll pass an empty
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// buffer instead
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fft_plan
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.r2c_plan
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.process_with_scratch(real_fft_buffer, &mut self.complex_fft_buffer, &mut [])
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.unwrap();
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// TODO: Do the thing
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// The DC and other low frequency bins doesn't contain much semantic meaning anymore
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// after all of this, so it only ends up consuming headroom.
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if self.params.dc_filter.value {
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// The Hann window function spreads the DC signal out slightly, so we'll clear
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// all 0-20 Hz bins for this.
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let highest_dcish_bin_idx =
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(20.0 / ((sample_rate / 2.0) / num_bins as f32)).floor() as usize;
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self.complex_fft_buffer[..highest_dcish_bin_idx + 1].fill(Complex32::default());
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}
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// Inverse FFT back into the scratch buffer. This will be added to a ring buffer
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// which gets written back to the host at a one block delay.
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fft_plan
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.c2r_plan
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.process_with_scratch(&mut self.complex_fft_buffer, real_fft_buffer, &mut [])
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.unwrap();
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// Apply the window function once more to reduce time domain aliasing. The gain
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// compensation compensates for the squared Hann window that would be applied if we
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// didn't do any processing at all as well as the FFT+IFFT itself.
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for (sample, window_sample) in real_fft_buffer.iter_mut().zip(&self.window_function)
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{
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*sample *= window_sample * output_gain;
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}
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});
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self.dry_wet_mixer.mix_in_dry(
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buffer,
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self.params
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.dry_wet_ratio
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.smoothed
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.next_step(buffer.len() as u32),
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// The dry and wet signals are in phase, so we can do a linear mix
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dry_wet_mixer::MixingStyle::Linear,
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self.stft.latency_samples() as usize,
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);
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ProcessStatus::Normal
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}
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}
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impl SpectralCompressor {
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/// `window_size` should not exceed `MAX_WINDOW_SIZE` or this will allocate.
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fn resize_for_window(&mut self, window_size: usize) {
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// The FFT algorithms for this window size have already been planned in
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// `self.plan_for_order`, and all of these data structures already have enough capacity, so
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// we just need to change some sizes.
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self.stft.set_block_size(window_size);
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self.window_function.resize(window_size, 0.0);
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util::window::hann_in_place(&mut self.window_function);
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self.complex_fft_buffer
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.resize(window_size / 2 + 1, Complex32::default());
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}
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}
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impl ClapPlugin for SpectralCompressor {
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const CLAP_ID: &'static str = "nl.robbertvanderhelm.spectral-compressor";
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const CLAP_DESCRIPTION: Option<&'static str> = Some("Turn things into pink noise on demand");
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const CLAP_MANUAL_URL: Option<&'static str> = Some(Self::URL);
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const CLAP_SUPPORT_URL: Option<&'static str> = None;
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const CLAP_FEATURES: &'static [ClapFeature] = &[
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ClapFeature::AudioEffect,
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ClapFeature::Stereo,
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ClapFeature::PhaseVocoder,
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ClapFeature::Compressor,
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ClapFeature::Custom("spectral"),
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ClapFeature::Custom("sosig"),
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];
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}
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impl Vst3Plugin for SpectralCompressor {
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const VST3_CLASS_ID: [u8; 16] = *b"SpectrlComprRvdH";
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const VST3_CATEGORIES: &'static str = "Fx|Dynamics|Spectral";
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}
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nih_export_clap!(SpectralCompressor);
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nih_export_vst3!(SpectralCompressor);
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