SE4
A stereo expander with variable envelope follower for RMS / peak behaviour. Based on the code for SC1.
rms);
free(plugin_data->as);
]]>
env_rms) {
env_rms = env_rms * ga + amp * (1.0f - ga);
} else {
env_rms = env_rms * gr + amp * (1.0f - gr);
}
if (lev_in > env_peak) {
env_peak = env_peak * ga + lev_in * (1.0f - ga);
} else {
env_peak = env_peak * gr + lev_in * (1.0f - gr);
}
if ((count++ & 3) == 3) {
amp = rms_env_process(rms, sum * 0.25f);
sum = 0.0f;
if (isnan(env_rms)) {
// This can happen sometimes, but I don't know why
env_rms = 0.0f;
}
env = LIN_INTERP(rms_peak, env_rms, env_peak);
if (env <= knee_min) {
gain_t = 1.0f;
} else if (env < knee_max) {
const float x = -(threshold - knee - lin2db(env)) / knee;
gain_t = db2lin(-knee * rs * x * x * 0.25f);
} else {
gain_t = db2lin((threshold - lin2db(env)) * rs);
}
}
gain = gain * ef_a + gain_t * ef_ai;
buffer_write(left_out[pos], left_in[pos] * gain * mug);
buffer_write(right_out[pos], right_in[pos] * gain * mug);
}
plugin_data->sum = sum;
plugin_data->amp = amp;
plugin_data->gain = gain;
plugin_data->gain_t = gain_t;
plugin_data->env = env;
plugin_data->env_rms = env_rms;
plugin_data->env_peak = env_peak;
plugin_data->count = count;
*(plugin_data->amplitude) = lin2db(env);
*(plugin_data->gain_exp) = lin2db(gain);
]]>
RMS/peak
The blanace between the RMS and peak envelope followers.
Attack time (ms)
The attack time in milliseconds.
Release time (ms)
The release time in milliseconds.
Threshold level (dB)
The point at which the expander will start to kick in.
Ratio (1:n)
The gain expansion ratio used when the signal level exceeds the threshold.
Knee radius (dB)
The distance from the threshold where the knee curve starts.
Attenuation (dB)
Controls the gain of the output signal in dB's. Used to correct for excessive amplitude caused by the extra dynamic range.
Amplitude (dB)
The level of the input signal, in decibels.
Gain expansion (dB)
The degree of gain expansion applied to the input signal, in decibels.
Left input
Right input
Left output
Right output