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Compute the analyzer data for Spectral Compressor

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This commit is contained in:
Robbert van der Helm 2023-03-19 15:09:08 +01:00
parent 9647f8f3dd
commit a18d70401b
1 changed files with 83 additions and 8 deletions
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91
plugins/spectral_compressor/src/compressor_bank.rs
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@ -560,6 +560,22 @@ impl CompressorBank {
) {
nih_debug_assert_eq!(buffer.len(), self.log2_freqs.len());
// The gain reduction amounts are accumulated in `self.analyzer_input_data`. When processing
// the last channel, this data is divided by the channel count, the envelope follower data
// is added, and the data is then sent to the editor so it can be displayed.
// `analyzer_input_data` contains excess capacity so it can handle any supported window
// size, so all operations on it are limited to the actual number of used bins.
let num_bins = buffer.len();
let num_channels = self.sidechain_spectrum_magnitudes.len();
let should_update_analyzer_data = params.editor_state.is_open();
if should_update_analyzer_data && channel_idx == 0 {
// NOTE: This may briefly show a huge amount of accumulated data when the editor has
// just been opened. If this doesn't look too obvious or too jarring this is
// probably worth letting it be like this.
let analyzer_input_data = self.analyzer_input_data.input_buffer();
analyzer_input_data.gain_reduction_db[..num_bins].fill(0.0);
}
self.update_if_needed(params);
match params.threshold.mode.value() {
ThresholdMode::Internal => {
@ -578,6 +594,44 @@ impl CompressorBank {
self.compress(buffer, channel_idx, params, first_non_dc_bin)
}
};
// When processing the last channel we can finalize the spectrum analyzer data and send it
// to the editor for display
if should_update_analyzer_data && channel_idx == num_channels - 1 {
let analyzer_input_data = self.analyzer_input_data.input_buffer();
// The gain reduction data needs to be averaged, see above
let channel_multiplier = (num_channels as f32).recip();
for gain_reduction_db in &mut analyzer_input_data.gain_reduction_db[..num_bins] {
*gain_reduction_db *= channel_multiplier;
}
// The spectrum analyzer data has not yet been added
assert!(self.envelopes.len() == num_channels);
assert!(self.envelopes[0].len() >= num_bins);
for (bin_idx, spectrum_data) in analyzer_input_data.spectrum[..num_bins]
.iter_mut()
.enumerate()
{
*spectrum_data = 0.0;
for channel_idx in 0..num_channels {
// SAFETY: These bounds are already checked
*spectrum_data += unsafe {
self.envelopes
.get_unchecked(channel_idx)
.get_unchecked(bin_idx)
};
}
*spectrum_data *= channel_multiplier;
}
// After filling the object with data it can be sent to the editor. This happens
// automatically when using the `.write()` interface, but since `AnalyzerData` contains
// a lot of padding and we only use the first `num_bins` of the arrays that would be a
// bit wasteful.
self.analyzer_input_data.publish();
}
}
/// Set the sidechain frequency spectrum magnitudes just before a [`process()`][Self::process()]
@ -714,15 +768,20 @@ impl CompressorBank {
/// Panics if the buffer does not have the same length as the one that was passed to the last
/// `resize()` call.
fn compress(
&self,
&mut self,
buffer: &mut [Complex32],
channel_idx: usize,
params: &SpectralCompressorParams,
first_non_dc_bin: usize,
) {
// The gain reduction values are always added to the arrays stored in this object. This
// makes it possible to visualize the gain reduction without a lot of conditionals.
let analyzer_input_data = self.analyzer_input_data.input_buffer();
let downwards_knee_width_db = params.compressors.downwards.knee_width_db.value();
let upwards_knee_width_db = params.compressors.upwards.knee_width_db.value();
assert!(analyzer_input_data.gain_reduction_db.len() >= buffer.len());
assert!(self.downwards_thresholds_db.len() == buffer.len());
assert!(self.downwards_ratios.len() == buffer.len());
assert!(self.downwards_knee_parabola_scale.len() == buffer.len());
@ -787,9 +846,14 @@ impl CompressorBank {
// If the comprssed output is -10 dBFS and the envelope follower was at -6 dBFS, then we
// want to apply -4 dB of gain to the bin
*bin *= util::db_to_gain_fast(
downwards_compressed + upwards_compressed - (envelope_db * 2.0),
);
let gain_reduction_db = downwards_compressed + upwards_compressed - (envelope_db * 2.0);
unsafe {
*analyzer_input_data
.gain_reduction_db
.get_unchecked_mut(bin_idx) += gain_reduction_db;
}
*bin *= util::db_to_gain_fast(gain_reduction_db);
}
}
@ -801,12 +865,15 @@ impl CompressorBank {
/// Panics if the buffer does not have the same length as the one that was passed to the last
/// `resize()` call.
fn compress_sidechain_match(
&self,
&mut self,
buffer: &mut [Complex32],
channel_idx: usize,
params: &SpectralCompressorParams,
first_non_dc_bin: usize,
) {
// See `compress()`
let analyzer_input_data = self.analyzer_input_data.input_buffer();
let downwards_knee_width_db = params.compressors.downwards.knee_width_db.value();
let upwards_knee_width_db = params.compressors.upwards.knee_width_db.value();
@ -815,6 +882,7 @@ impl CompressorBank {
let other_channels_t = params.threshold.sc_channel_link.value() / num_channels;
let this_channel_t = 1.0 - (other_channels_t * (num_channels - 1.0));
assert!(analyzer_input_data.gain_reduction_db.len() >= buffer.len());
assert!(self.sidechain_spectrum_magnitudes[channel_idx].len() == buffer.len());
assert!(self.downwards_thresholds_db.len() == buffer.len());
assert!(self.downwards_ratios.len() == buffer.len());
@ -893,9 +961,16 @@ impl CompressorBank {
envelope_db
};
*bin *= util::db_to_gain_fast(
downwards_compressed + upwards_compressed - (envelope_db * 2.0),
);
// If the comprssed output is -10 dBFS and the envelope follower was at -6 dBFS, then we
// want to apply -4 dB of gain to the bin
let gain_reduction_db = downwards_compressed + upwards_compressed - (envelope_db * 2.0);
unsafe {
*analyzer_input_data
.gain_reduction_db
.get_unchecked_mut(bin_idx) += gain_reduction_db;
}
*bin *= util::db_to_gain_fast(gain_reduction_db);
}
}