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obs-filters: Add upward compressor filter
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An upward compressor increases levels below a threshold, instead of
decreasing levels above it. This is closely related to an expander; the
upward compressor can be seen as an expander with ratio in the [0,1]
range. This can be used for example when the game audio is lowered
against a voice track but that one still wants to be able to hear very
low game sounds.

For more use cases:
https://www.izotope.com/en/learn/4-tips-for-using-upwards-compression-in-neutron.html

Signed-off-by: pkv <pkv@obsproject.com>
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@pkviet @jp9000
pkviet authored and jp9000 committed Oct 27, 2022
1 parent 56cfaf7 commit 8d45771
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Showing 3 changed files with 104 additions and 48 deletions.
1 change: 1 addition & 0 deletions plugins/obs-filters/data/locale/en-US.ini
View file
Original file line number Diff line number Diff line change
Expand Up @@ -124,3 +124,4 @@ Greenscreen.Mode="Mode"
Greenscreen.Quality="Quality (higher GPU usage, better quality)"
Greenscreen.Performance="Performance (lower GPU usage, good quality)"
Greenscreen.Threshold="Threshold"
Upward.Compressor="Upward Compresor"
149 changes: 101 additions & 48 deletions plugins/obs-filters/expander-filter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,8 @@

/* -------------------------------------------------------- */

#define do_log(level, format, ...) \
blog(level, "[expander: '%s'] " format, \
#define do_log(level, format, ...) \
blog(level, "[expander/gate/upward compressor: '%s'] " format, \
obs_source_get_name(cd->context), ##__VA_ARGS__)

#define warn(format, ...) do_log(LOG_WARNING, format, ##__VA_ARGS__)
Expand Down Expand Up @@ -51,6 +51,8 @@

#define MIN_RATIO 1.0f
#define MAX_RATIO 20.0f
#define MIN_RATIO_UPW 0.0f
#define MAX_RATIO_UPW 1.0f
#define MIN_THRESHOLD_DB -60.0f
#define MAX_THRESHOLD_DB 0.0f
#define MIN_OUTPUT_GAIN_DB -32.0f
Expand Down Expand Up @@ -92,6 +94,7 @@ struct expander_data {
float gain_db_buf[MAX_AUDIO_CHANNELS];
float *env_in;
size_t env_in_len;
bool is_upwcomp;
};

enum {
Expand Down Expand Up @@ -144,6 +147,12 @@ static const char *expander_name(void *unused)
return obs_module_text("Expander");
}

static const char *upward_compressor_name(void *unused)
{
UNUSED_PARAMETER(unused);
return obs_module_text("Upward.Compressor");
}

static void expander_defaults(obs_data_t *s)
{
const char *presets = obs_data_get_string(s, S_PRESETS);
Expand All @@ -162,21 +171,33 @@ static void expander_defaults(obs_data_t *s)
obs_data_set_default_string(s, S_DETECTOR, "RMS");
}

static void upward_compressor_defaults(obs_data_t *s)
{
obs_data_set_default_double(s, S_RATIO, 0.5);
obs_data_set_default_double(s, S_THRESHOLD, -20.0f);
obs_data_set_default_int(s, S_ATTACK_TIME, 10);
obs_data_set_default_int(s, S_RELEASE_TIME, 50);
obs_data_set_default_double(s, S_OUTPUT_GAIN, 0.0);
obs_data_set_default_string(s, S_DETECTOR, "peak");
}

static void expander_update(void *data, obs_data_t *s)
{
struct expander_data *cd = data;
const char *presets = obs_data_get_string(s, S_PRESETS);
if (strcmp(presets, "expander") == 0 && cd->is_gate) {
obs_data_clear(s);
obs_data_set_string(s, S_PRESETS, "expander");
expander_defaults(s);
cd->is_gate = false;
}
if (strcmp(presets, "gate") == 0 && !cd->is_gate) {
obs_data_clear(s);
obs_data_set_string(s, S_PRESETS, "gate");
expander_defaults(s);
cd->is_gate = true;
if (!cd->is_upwcomp) {
const char *presets = obs_data_get_string(s, S_PRESETS);
if (strcmp(presets, "expander") == 0 && cd->is_gate) {
obs_data_clear(s);
obs_data_set_string(s, S_PRESETS, "expander");
expander_defaults(s);
cd->is_gate = false;
}
if (strcmp(presets, "gate") == 0 && !cd->is_gate) {
obs_data_clear(s);
obs_data_set_string(s, S_PRESETS, "gate");
expander_defaults(s);
cd->is_gate = true;
}
}

const uint32_t sample_rate =
Expand Down Expand Up @@ -217,7 +238,9 @@ static void expander_update(void *data, obs_data_t *s)
resize_gain_db_buffer(cd, sample_len);
}

static void *expander_create(obs_data_t *settings, obs_source_t *filter)
static void *compressor_expander_create(obs_data_t *settings,
obs_source_t *filter,
bool is_compressor)
{
struct expander_data *cd = bzalloc(sizeof(struct expander_data));
cd->context = filter;
Expand All @@ -230,11 +253,22 @@ static void *expander_create(obs_data_t *settings, obs_source_t *filter)
const char *presets = obs_data_get_string(settings, S_PRESETS);
if (strcmp(presets, "gate") == 0)
cd->is_gate = true;

cd->is_upwcomp = is_compressor;
expander_update(cd, settings);
return cd;
}

static void *expander_create(obs_data_t *settings, obs_source_t *filter)
{
return compressor_expander_create(settings, filter, false);
}

static void *upward_compressor_create(obs_data_t *settings,
obs_source_t *filter)
{
return compressor_expander_create(settings, filter, true);
}

static void expander_destroy(void *data)
{
struct expander_data *cd = data;
Expand Down Expand Up @@ -305,17 +339,21 @@ 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)
float *gain_db, bool is_upwcomp,
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;

if (is_upwcomp && env_db <= -60.0f)
diff = 0.0f;

float gain = diff > 0.0f ? fmaxf(slope * diff, -60.0f) : 0.0f;
float prev_gain = gain_db[idx - 1];

Expand All @@ -341,7 +379,11 @@ static inline void process_sample(size_t idx, float *samples, float *env_buf,
/* --------------------------------- */
/* output */

gain = db_to_mul(fminf(0.0f, gain_db[idx]));
float min_val =
is_upwcomp ? fminf(diff, threshold - mul_to_db(samples[idx]))
: 0.0f;

gain = db_to_mul(fminf(min_val, gain_db[idx]));
samples[idx] *= gain * output_gain;
}

Expand All @@ -356,6 +398,7 @@ static inline void process_expansion(struct expander_data *cd, float **samples,
const float threshold = cd->threshold;
const float slope = cd->slope;
const float output_gain = cd->output_gain;
const bool is_upwcomp = cd->is_upwcomp;

if (cd->gain_db_len < num_samples)
resize_gain_db_buffer(cd, num_samples);
Expand All @@ -372,8 +415,8 @@ static inline void process_expansion(struct expander_data *cd, float **samples,

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,
is_upwcomp, channel_gain, threshold,
slope, attack_gain, inv_attack_gain,
release_gain, inv_release_gain,
output_gain);
}
Expand All @@ -397,28 +440,25 @@ expander_filter_audio(void *data, struct obs_audio_data *audio)
return audio;
}

static bool presets_changed(obs_properties_t *props, obs_property_t *prop,
obs_data_t *settings)
{
UNUSED_PARAMETER(props);
UNUSED_PARAMETER(prop);
UNUSED_PARAMETER(settings);
return true;
}

static obs_properties_t *expander_properties(void *data)
{
struct expander_data *cd = data;
obs_properties_t *props = obs_properties_create();
obs_property_t *p;
if (!cd->is_upwcomp) {
obs_property_t *presets = obs_properties_add_list(
props, S_PRESETS, TEXT_PRESETS, OBS_COMBO_TYPE_LIST,
OBS_COMBO_FORMAT_STRING);
obs_property_list_add_string(presets, TEXT_PRESETS_EXP,
"expander");
obs_property_list_add_string(presets, TEXT_PRESETS_GATE,
"gate");
}

obs_property_t *presets = obs_properties_add_list(
props, S_PRESETS, TEXT_PRESETS, OBS_COMBO_TYPE_LIST,
OBS_COMBO_FORMAT_STRING);
obs_property_list_add_string(presets, TEXT_PRESETS_EXP, "expander");
obs_property_list_add_string(presets, TEXT_PRESETS_GATE, "gate");
obs_property_set_modified_callback(presets, presets_changed);
p = obs_properties_add_float_slider(props, S_RATIO, TEXT_RATIO,
MIN_RATIO, MAX_RATIO, 0.1);
p = obs_properties_add_float_slider(
props, S_RATIO, TEXT_RATIO,
!cd->is_upwcomp ? MIN_RATIO : MIN_RATIO_UPW,
!cd->is_upwcomp ? MAX_RATIO : MAX_RATIO_UPW, 0.1);
obs_property_float_set_suffix(p, ":1");
p = obs_properties_add_float_slider(props, S_THRESHOLD, TEXT_THRESHOLD,
MIN_THRESHOLD_DB, MAX_THRESHOLD_DB,
Expand All @@ -437,13 +477,13 @@ static obs_properties_t *expander_properties(void *data)
MIN_OUTPUT_GAIN_DB,
MAX_OUTPUT_GAIN_DB, 0.1);
obs_property_float_set_suffix(p, " dB");
obs_property_t *detect = obs_properties_add_list(
props, S_DETECTOR, TEXT_DETECTOR, OBS_COMBO_TYPE_LIST,
OBS_COMBO_FORMAT_STRING);
obs_property_list_add_string(detect, TEXT_RMS, "RMS");
obs_property_list_add_string(detect, TEXT_PEAK, "peak");

UNUSED_PARAMETER(data);
if (!cd->is_upwcomp) {
obs_property_t *detect = obs_properties_add_list(
props, S_DETECTOR, TEXT_DETECTOR, OBS_COMBO_TYPE_LIST,
OBS_COMBO_FORMAT_STRING);
obs_property_list_add_string(detect, TEXT_RMS, "RMS");
obs_property_list_add_string(detect, TEXT_PEAK, "peak");
}
return props;
}

Expand All @@ -459,3 +499,16 @@ struct obs_source_info expander_filter = {
.get_defaults = expander_defaults,
.get_properties = expander_properties,
};

struct obs_source_info upward_compressor_filter = {
.id = "upward_compressor_filter",
.type = OBS_SOURCE_TYPE_FILTER,
.output_flags = OBS_SOURCE_AUDIO,
.get_name = upward_compressor_name,
.create = upward_compressor_create,
.destroy = expander_destroy,
.update = expander_update,
.filter_audio = expander_filter_audio,
.get_defaults = upward_compressor_defaults,
.get_properties = expander_properties,
};
2 changes: 2 additions & 0 deletions plugins/obs-filters/obs-filters.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ extern struct obs_source_info noise_gate_filter;
extern struct obs_source_info compressor_filter;
extern struct obs_source_info limiter_filter;
extern struct obs_source_info expander_filter;
extern struct obs_source_info upward_compressor_filter;
extern struct obs_source_info luma_key_filter;
extern struct obs_source_info luma_key_filter_v2;
#ifdef LIBNVVFX_ENABLED
Expand Down Expand Up @@ -77,6 +78,7 @@ bool obs_module_load(void)
obs_register_source(&compressor_filter);
obs_register_source(&limiter_filter);
obs_register_source(&expander_filter);
obs_register_source(&upward_compressor_filter);
obs_register_source(&luma_key_filter);
obs_register_source(&luma_key_filter_v2);
#ifdef LIBNVVFX_ENABLED
Expand Down

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