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obs-filters: Ensure gain is positive for upward compressor
The gain should be positive for an upward compressor. Initially, the
gain would be zeroe'd below -60 dB to ensure noise is not amplified by
the upward compressor. This created a discontinuity at -60 dB since
just above -60 dB, the audio is boosted by +20 dB (at default
settings). This was fixed in commit 50db097
which decreased smoothly
the gain so that it's 0 dB at -60 dB. However that commit forgot to
limit the gain decrease which was negative below -60 dB.
This is fixed by the current commit.
Additionally initialization allowed -inf gain. We hard limit to positive
gains only as they should be for an upward compressor.
The bugfix was found by R1ch and put in form by pkv.
Co-authored-by: pkv <pkv@obsproject.com>
Signed-off-by: pkv <pkv@obsproject.com>
This commit is contained in:
parent
96aef4f048
commit
eef0faf741
@ -360,12 +360,15 @@ static inline void process_sample(size_t idx, float *samples, float *env_buf,
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float diff = threshold - env_db;
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float diff = threshold - env_db;
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if (is_upwcomp && env_db <= (threshold - 60.0f) / 2)
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if (is_upwcomp && env_db <= (threshold - 60.0f) / 2)
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diff = env_db + 60.0f;
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diff = env_db + 60.0f > 0 ? env_db + 60.0f : 0.0f;
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float gain = 0.0f;
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float gain = 0.0f;
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float prev_gain = 0.0f;
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// Note that the gain is always >= 0 for the upward compressor
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// Note that the gain is always >= 0 for the upward compressor
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// but is always <=0 for the expander.
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// but is always <=0 for the expander.
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if (is_upwcomp) {
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if (is_upwcomp) {
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prev_gain = idx > 0 ? fmaxf(gain_db[idx - 1], 0)
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: fmaxf(channel_gain, 0);
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// gain above knee (included for clarity):
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// gain above knee (included for clarity):
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if (env_db >= threshold + knee / 2)
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if (env_db >= threshold + knee / 2)
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gain = 0.0f;
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gain = 0.0f;
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@ -377,9 +380,9 @@ static inline void process_sample(size_t idx, float *samples, float *env_buf,
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threshold + knee / 2 > env_db)
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threshold + knee / 2 > env_db)
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gain = slope * powf(diff + knee / 2, 2) / (2.0f * knee);
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gain = slope * powf(diff + knee / 2, 2) / (2.0f * knee);
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} else {
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} else {
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prev_gain = idx > 0 ? gain_db[idx - 1] : channel_gain;
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gain = diff > 0.0f ? fmaxf(slope * diff, -60.0f) : 0.0f;
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gain = diff > 0.0f ? fmaxf(slope * diff, -60.0f) : 0.0f;
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}
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}
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float prev_gain = idx > 0 ? gain_db[idx - 1] : channel_gain;
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/* --------------------------------- */
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/* --------------------------------- */
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/* ballistics (attack/release) */
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/* ballistics (attack/release) */
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