diff --git a/plugins/obs-filters/CMakeLists.txt b/plugins/obs-filters/CMakeLists.txt index 23a985425..32854833a 100644 --- a/plugins/obs-filters/CMakeLists.txt +++ b/plugins/obs-filters/CMakeLists.txt @@ -49,7 +49,8 @@ set(obs-filters_SOURCES noise-gate-filter.c mask-filter.c invert-audio-polarity.c - compressor-filter.c) + compressor-filter.c + limiter-filter.c) add_library(obs-filters MODULE ${obs-filters_SOURCES} diff --git a/plugins/obs-filters/data/locale/en-US.ini b/plugins/obs-filters/data/locale/en-US.ini index 7ebaf97b7..a055d54a2 100644 --- a/plugins/obs-filters/data/locale/en-US.ini +++ b/plugins/obs-filters/data/locale/en-US.ini @@ -76,3 +76,6 @@ Compressor.AttackTime="Attack (ms)" Compressor.ReleaseTime="Release (ms)" Compressor.OutputGain="Output Gain (dB)" Compressor.SidechainSource="Sidechain/Ducking Source" +Limiter="Limiter" +Limiter.Threshold="Threshold (dB)" +Limiter.ReleaseTime="Release (ms)" diff --git a/plugins/obs-filters/limiter-filter.c b/plugins/obs-filters/limiter-filter.c new file mode 100644 index 000000000..158111673 --- /dev/null +++ b/plugins/obs-filters/limiter-filter.c @@ -0,0 +1,216 @@ +#include +#include +#include + +#include +#include +#include + +/* -------------------------------------------------------- */ + +#define do_log(level, format, ...) \ + blog(level, "[limiter: '%s'] " format, \ + obs_source_get_name(cd->context), ##__VA_ARGS__) + +#define warn(format, ...) do_log(LOG_WARNING, format, ##__VA_ARGS__) +#define info(format, ...) do_log(LOG_INFO, format, ##__VA_ARGS__) + +#ifdef _DEBUG +#define debug(format, ...) do_log(LOG_DEBUG, format, ##__VA_ARGS__) +#else +#define debug(format, ...) +#endif + +/* -------------------------------------------------------- */ + +#define S_THRESHOLD "threshold" +#define S_RELEASE_TIME "release_time" + +#define MT_ obs_module_text +#define TEXT_THRESHOLD MT_("Limiter.Threshold") +#define TEXT_RELEASE_TIME MT_("Limiter.ReleaseTime") + +#define MIN_THRESHOLD_DB -60.0 +#define MAX_THRESHOLD_DB 0.0f +#define MIN_ATK_RLS_MS 1 +#define MAX_RLS_MS 1000 +#define DEFAULT_AUDIO_BUF_MS 10 +#define ATK_TIME 0.001f +#define MS_IN_S 1000 +#define MS_IN_S_F ((float)MS_IN_S) + +/* -------------------------------------------------------- */ + +struct limiter_data { + obs_source_t *context; + float *envelope_buf; + size_t envelope_buf_len; + + float threshold; + float attack_gain; + float release_gain; + float output_gain; + + size_t num_channels; + size_t sample_rate; + float envelope; + float slope; +}; + +/* -------------------------------------------------------- */ + +static void resize_env_buffer(struct limiter_data *cd, size_t len) +{ + cd->envelope_buf_len = len; + cd->envelope_buf = brealloc(cd->envelope_buf, len * sizeof(float)); +} + +static inline float gain_coefficient(uint32_t sample_rate, float time) +{ + return (float)exp(-1.0f / (sample_rate * time)); +} + +static const char *limiter_name(void *unused) +{ + UNUSED_PARAMETER(unused); + return obs_module_text("Limiter"); +} + +static void limiter_update(void *data, obs_data_t *s) +{ + struct limiter_data *cd = data; + + const uint32_t sample_rate = + audio_output_get_sample_rate(obs_get_audio()); + const size_t num_channels = + audio_output_get_channels(obs_get_audio()); + float attack_time_ms = ATK_TIME; + + const float release_time_ms = + (float)obs_data_get_int(s, S_RELEASE_TIME); + const float output_gain_db = 0; + + cd->threshold = (float)obs_data_get_double(s, S_THRESHOLD); + + cd->attack_gain = gain_coefficient(sample_rate, + attack_time_ms / MS_IN_S_F); + cd->release_gain = gain_coefficient(sample_rate, + release_time_ms / MS_IN_S_F); + cd->output_gain = db_to_mul(output_gain_db); + cd->num_channels = num_channels; + cd->sample_rate = sample_rate; + cd->slope = 1.0f; + + size_t sample_len = sample_rate * DEFAULT_AUDIO_BUF_MS / MS_IN_S; + if (cd->envelope_buf_len == 0) + resize_env_buffer(cd, sample_len); +} + +static void *limiter_create(obs_data_t *settings, obs_source_t *filter) +{ + struct limiter_data *cd = bzalloc(sizeof(struct limiter_data)); + cd->context = filter; + + limiter_update(cd, settings); + return cd; +} + +static void limiter_destroy(void *data) +{ + struct limiter_data *cd = data; + + bfree(cd->envelope_buf); + bfree(cd); +} + +static void analyze_envelope(struct limiter_data *cd, + float **samples, const uint32_t num_samples) +{ + if (cd->envelope_buf_len < num_samples) { + resize_env_buffer(cd, num_samples); + } + + const float attack_gain = cd->attack_gain; + const float release_gain = cd->release_gain; + + memset(cd->envelope_buf, 0, num_samples * sizeof(cd->envelope_buf[0])); + for (size_t chan = 0; chan < cd->num_channels; ++chan) { + if (!samples[chan]) + continue; + + float *envelope_buf = cd->envelope_buf; + float env = cd->envelope; + for (uint32_t i = 0; i < num_samples; ++i) { + const float env_in = fabsf(samples[chan][i]); + if (env < env_in) { + env = env_in + attack_gain * (env - env_in); + } else { + env = env_in + release_gain * (env - env_in); + } + envelope_buf[i] = fmaxf(envelope_buf[i], env); + } + } + cd->envelope = cd->envelope_buf[num_samples - 1]; +} + +static inline void process_compression(const struct limiter_data *cd, + float **samples, uint32_t num_samples) +{ + for (size_t i = 0; i < num_samples; ++i) { + const float env_db = mul_to_db(cd->envelope_buf[i]); + float gain = cd->slope * (cd->threshold - env_db); + gain = db_to_mul(fminf(0, gain)); + + for (size_t c = 0; c < cd->num_channels; ++c) { + if (samples[c]) { + samples[c][i] *= gain * cd->output_gain; + } + } + } +} + +static struct obs_audio_data *limiter_filter_audio(void *data, + struct obs_audio_data *audio) +{ + struct limiter_data *cd = data; + + const uint32_t num_samples = audio->frames; + if (num_samples == 0) + return audio; + + float **samples = (float**)audio->data; + analyze_envelope(cd, samples, num_samples); + process_compression(cd, samples, num_samples); + return audio; +} + +static void limiter_defaults(obs_data_t *s) +{ + obs_data_set_default_double(s, S_THRESHOLD, -6.0f); + obs_data_set_default_int(s, S_RELEASE_TIME, 60); +} + +static obs_properties_t *limiter_properties(void *data) +{ + struct limiter_data *cd = data; + obs_properties_t *props = obs_properties_create(); + + obs_properties_add_float_slider(props, S_THRESHOLD, TEXT_THRESHOLD, MIN_THRESHOLD_DB, MAX_THRESHOLD_DB, 0.1); + obs_properties_add_int_slider(props, S_RELEASE_TIME, TEXT_RELEASE_TIME, MIN_ATK_RLS_MS, MAX_RLS_MS, 1); + + UNUSED_PARAMETER(data); + return props; +} + +struct obs_source_info limiter_filter = { + .id = "limiter_filter", + .type = OBS_SOURCE_TYPE_FILTER, + .output_flags = OBS_SOURCE_AUDIO, + .get_name = limiter_name, + .create = limiter_create, + .destroy = limiter_destroy, + .update = limiter_update, + .filter_audio = limiter_filter_audio, + .get_defaults = limiter_defaults, + .get_properties = limiter_properties, +}; diff --git a/plugins/obs-filters/obs-filters.c b/plugins/obs-filters/obs-filters.c index 53cf16ad6..9751720e2 100644 --- a/plugins/obs-filters/obs-filters.c +++ b/plugins/obs-filters/obs-filters.c @@ -26,6 +26,7 @@ extern struct obs_source_info noise_suppress_filter; extern struct obs_source_info invert_polarity_filter; extern struct obs_source_info noise_gate_filter; extern struct obs_source_info compressor_filter; +extern struct obs_source_info limiter_filter; bool obs_module_load(void) { @@ -47,5 +48,6 @@ bool obs_module_load(void) obs_register_source(&invert_polarity_filter); obs_register_source(&noise_gate_filter); obs_register_source(&compressor_filter); + obs_register_source(&limiter_filter); return true; }