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obs-filters: Refactor expander filter expansion code

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Things were a bit unoptimal and were squished together, making the code
much more difficult to work with. Instead, separate the code for
processing individual samples into its own function.
This commit is contained in:
Jim 2022-10-26 21:14:10 -07:00
parent 89006716b4
commit 56cfaf792d
1 changed files with 59 additions and 38 deletions
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97
plugins/obs-filters/expander-filter.c
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@ -304,59 +304,80 @@ static void analyze_envelope(struct expander_data *cd, float **samples,
}
}
static inline void process_sample(size_t idx, float *samples, float *env_buf,
float *gain_db, float channel_gain,
float threshold, float slope,
float attack_gain, float inv_attack_gain,
float release_gain, float inv_release_gain,
float output_gain)
{
/* --------------------------------- */
/* gain stage of expansion */
float env_db = mul_to_db(env_buf[idx]);
float diff = threshold - env_db;
float gain = diff > 0.0f ? fmaxf(slope * diff, -60.0f) : 0.0f;
float prev_gain = gain_db[idx - 1];
/* --------------------------------- */
/* ballastics (attack/release) */
if (idx > 0) {
if (gain > prev_gain)
gain_db[idx] = attack_gain * prev_gain +
inv_attack_gain * gain;
else
gain_db[idx] = release_gain * prev_gain +
inv_release_gain * gain;
} else {
if (gain > channel_gain)
gain_db[idx] = attack_gain * channel_gain +
inv_attack_gain * gain;
else
gain_db[idx] = release_gain * channel_gain +
inv_release_gain * gain;
}
/* --------------------------------- */
/* output */
gain = db_to_mul(fminf(0.0f, gain_db[idx]));
samples[idx] *= gain * output_gain;
}
// gain stage and ballistics in dB domain
static inline void process_expansion(struct expander_data *cd, float **samples,
uint32_t num_samples)
{
const float attack_gain = cd->attack_gain;
const float release_gain = cd->release_gain;
const float inv_attack_gain = 1.0f - attack_gain;
const float inv_release_gain = 1.0f - release_gain;
const float threshold = cd->threshold;
const float slope = cd->slope;
const float output_gain = cd->output_gain;
if (cd->gain_db_len < num_samples)
resize_gain_db_buffer(cd, num_samples);
for (int i = 0; i < MAX_AUDIO_CHANNELS; i++)
for (size_t i = 0; i < cd->num_channels; i++)
memset(cd->gain_db[i], 0,
num_samples * sizeof(cd->gain_db[i][0]));
for (size_t chan = 0; chan < cd->num_channels; chan++) {
for (size_t i = 0; i < num_samples; ++i) {
// gain stage of expansion
float env_db = mul_to_db(cd->envelope_buf[chan][i]);
float gain =
cd->threshold - env_db > 0.0f
? fmaxf(cd->slope * (cd->threshold -
env_db),
-60.0f)
: 0.0f;
// ballistics (attack/release)
if (i > 0) {
if (gain > cd->gain_db[chan][i - 1])
cd->gain_db[chan][i] =
attack_gain *
cd->gain_db[chan][i - 1] +
(1.0f - attack_gain) * gain;
else
cd->gain_db[chan][i] =
release_gain *
cd->gain_db[chan][i - 1] +
(1.0f - release_gain) * gain;
} else {
if (gain > cd->gain_db_buf[chan])
cd->gain_db[chan][i] =
attack_gain *
cd->gain_db_buf[chan] +
(1.0f - attack_gain) * gain;
else
cd->gain_db[chan][i] =
release_gain *
cd->gain_db_buf[chan] +
(1.0f - release_gain) * gain;
}
float *channel_samples = samples[chan];
float *env_buf = cd->envelope_buf[chan];
float *gain_db = cd->gain_db[chan];
float channel_gain = cd->gain_db_buf[chan];
gain = db_to_mul(fminf(0, cd->gain_db[chan][i]));
if (samples[chan])
samples[chan][i] *= gain * cd->output_gain;
for (size_t i = 0; i < num_samples; ++i) {
process_sample(i, channel_samples, env_buf, gain_db,
channel_gain, threshold, slope,
attack_gain, inv_attack_gain,
release_gain, inv_release_gain,
output_gain);
}
cd->gain_db_buf[chan] = cd->gain_db[chan][num_samples - 1];
cd->gain_db_buf[chan] = gain_db[num_samples - 1];
}
}