obs-filters: Add speexdsp-based noise suppression filter

plugins/obs-filters/CMakeLists.txt

 project(obs-filters)
 
+find_package(Libspeexdsp QUIET)
+if(LIBSPEEXDSP_FOUND)
+	set(obs-filters_LIBSPEEXDSP_SOURCES
+		noise-suppress-filter.c)
+	set(obs-filters_LIBSPEEXDSP_LIBRARIES
+		${LIBSPEEXDSP_LIBRARIES})
+else()
+	message(STATUS "Speexdsp library not found, speexdsp filters disabled")
+endif()
+
+configure_file("${CMAKE_CURRENT_SOURCE_DIR}/obs-filters-config.h.in"
+	"${CMAKE_BINARY_DIR}/plugins/obs-filters/config/obs-filters-config.h")
+
+set(obs-filters_config_HEADERS
+	"${CMAKE_BINARY_DIR}/plugins/obs-filters/config/obs-filters-config.h")
+include_directories(${LIBSPEEXDSP_INCLUDE_DIRS}
+	"${CMAKE_BINARY_DIR}/plugins/obs-filters/config")
+
 set(obs-filters_SOURCES
 	obs-filters.c
 	color-filter.c
@@ -15,8 +33,11 @@ set(obs-filters_SOURCES
 	mask-filter.c)
 
 add_library(obs-filters MODULE
-	${obs-filters_SOURCES})
+	${obs-filters_SOURCES}
+	${obs-filters_config_HEADERS}
+	${obs-filters_LIBSPEEXDSP_SOURCES})
 target_link_libraries(obs-filters
-	libobs)
+	libobs
+	${obs-filters_LIBSPEEXDSP_LIBRARIES})
 
 install_obs_plugin_with_data(obs-filters data)

plugins/obs-filters/data/locale/en-US.ini

@@ -8,6 +8,7 @@ ColorKeyFilter="Color Key"
 SharpnessFilter="Sharpen"
 ScaleFilter="Scaling/Aspect Ratio"
 NoiseGate="Noise Gate"
+NoiseSuppress="Noise Suppression"
 Gain="Gain"
 DelayMs="Delay (milliseconds)"
 Type="Type"
@@ -59,3 +60,4 @@ ScaleFiltering.Point="Point"
 ScaleFiltering.Bilinear="Bilinear"
 ScaleFiltering.Bicubic="Bicubic"
 ScaleFiltering.Lanczos="Lanczos"
+NoiseSuppress.SuppressLevel="Suppression Level (dB)"

plugins/obs-filters/noise-suppress-filter.c

+#include <stdint.h>
+#include <inttypes.h>
+
+#include <obs-module.h>
+#include <speex/speex_preprocess.h>
+
+/* -------------------------------------------------------- */
+
+#define do_log(level, format, ...) \
+	blog(level, "[noise suppress: '%s'] " format, \
+			obs_source_get_name(ng->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_SUPPRESS_LEVEL                "suppress_level"
+
+#define MT_ obs_module_text
+#define TEXT_SUPPRESS_LEVEL             MT_("NoiseSuppress.SuppressLevel")
+
+#define MAX_PREPROC_CHANNELS            2
+
+/* -------------------------------------------------------- */
+
+struct noise_suppress_data {
+	obs_source_t *context;
+
+	/* Speex preprocessor state */
+	SpeexPreprocessState *states[MAX_PREPROC_CHANNELS];
+
+	/* 16 bit PCM buffers */
+	spx_int16_t *segment_buffers[MAX_PREPROC_CHANNELS];
+
+	int suppress_level;
+};
+
+/* -------------------------------------------------------- */
+
+#define SUP_MIN -60
+#define SUP_MAX 0
+
+static const float c_32_to_16 = (float)INT16_MAX;
+static const float c_16_to_32 = ((float)INT16_MAX + 1.0f);
+
+/* -------------------------------------------------------- */
+
+static const char *noise_suppress_name(void *unused)
+{
+	UNUSED_PARAMETER(unused);
+	return obs_module_text("NoiseSuppress");
+}
+
+static void noise_suppress_destroy(void *data)
+{
+	struct noise_suppress_data *ng = data;
+
+	for (size_t i = 0; i < MAX_PREPROC_CHANNELS; i++) {
+		speex_preprocess_state_destroy(ng->states[i]);
+		bfree(ng->segment_buffers[i]);
+	}
+
+	bfree(ng);
+}
+
+static inline void alloc_channel(struct noise_suppress_data *ng,
+		uint32_t sample_rate, size_t channel, uint32_t size)
+{
+	if (ng->states[channel])
+		return;
+
+	debug("Create channel %d speex state", (int)channel);
+	ng->states[channel] = speex_preprocess_state_init(size, sample_rate);
+
+	if (!ng->segment_buffers[channel]) {
+		ng->segment_buffers[channel] =
+			bzalloc(size * sizeof(spx_int16_t));
+		debug("Create channel %d speex buffer: size = %"PRIu32,
+				(int)channel, size);
+	}
+}
+
+static void noise_suppress_update(void *data, obs_data_t *s)
+{
+	struct noise_suppress_data *ng = data;
+
+	int suppress_level = (int)obs_data_get_int(s, S_SUPPRESS_LEVEL);
+	uint32_t sample_rate = audio_output_get_sample_rate(obs_get_audio());
+	uint32_t segment_size = sample_rate / 100;
+	size_t channels = audio_output_get_channels(obs_get_audio());
+
+	ng->suppress_level = suppress_level;
+
+	debug("channels = %d", (int)channels);
+	debug("sample_rate = %"PRIu32, sample_rate);
+	debug("segment_size = %u"PRIu32, segment_size);
+	debug("block size = %d",
+			(int)audio_output_get_block_size(obs_get_audio()));
+
+	/* One speex state for each channel (limit 2) */
+	for (size_t i = 0; i < channels; i++)
+		alloc_channel(ng, sample_rate, i, segment_size);
+}
+
+static void *noise_suppress_create(obs_data_t *settings, obs_source_t *filter)
+{
+	struct noise_suppress_data *ng =
+		bzalloc(sizeof(struct noise_suppress_data));
+
+	ng->context = filter;
+	noise_suppress_update(ng, settings);
+	return ng;
+}
+
+static inline void process_channel(struct noise_suppress_data *ng,
+		size_t channel, size_t frames, float *adata[2])
+{
+	/* Set args */
+	speex_preprocess_ctl(ng->states[channel],
+			SPEEX_PREPROCESS_SET_NOISE_SUPPRESS,
+			&ng->suppress_level);
+
+	/* Convert to 16bit */
+	for (size_t i = 0; i < frames; i++)
+		ng->segment_buffers[channel][i] =
+			(spx_int16_t)(adata[channel][i] * c_32_to_16);
+
+	/* Execute */
+	speex_preprocess_run(ng->states[channel], ng->segment_buffers[channel]);
+
+	/* Convert back to 32bit */
+	for (size_t i = 0; i < frames; i++)
+		adata[channel][i] =
+			(float)ng->segment_buffers[channel][i] / c_16_to_32;
+}
+
+static struct obs_audio_data *noise_suppress_filter_audio(void *data,
+	struct obs_audio_data *audio)
+{
+	struct noise_suppress_data *ng = data;
+	float *adata[2] = {(float*)audio->data[0], (float*)audio->data[1]};
+
+	/* Execute for each available channel */
+	for (size_t i = 0; i < MAX_PREPROC_CHANNELS; i++) {
+		if (ng->states[i])
+			process_channel(ng, i, audio->frames, adata);
+	}
+
+	return audio;
+}
+
+static void noise_suppress_defaults(obs_data_t *s)
+{
+	obs_data_set_default_int(s, S_SUPPRESS_LEVEL, -30);
+}
+
+static obs_properties_t *noise_suppress_properties(void *data)
+{
+	obs_properties_t *ppts = obs_properties_create();
+
+	obs_properties_add_int_slider(ppts, S_SUPPRESS_LEVEL,
+			TEXT_SUPPRESS_LEVEL, SUP_MIN, SUP_MAX, 0);
+
+	UNUSED_PARAMETER(data);
+	return ppts;
+}
+
+struct obs_source_info noise_suppress_filter = {
+	.id = "noise_suppress_filter",
+	.type = OBS_SOURCE_TYPE_FILTER,
+	.output_flags = OBS_SOURCE_AUDIO,
+	.get_name = noise_suppress_name,
+	.create = noise_suppress_create,
+	.destroy = noise_suppress_destroy,
+	.update = noise_suppress_update,
+	.filter_audio = noise_suppress_filter_audio,
+	.get_defaults = noise_suppress_defaults,
+	.get_properties = noise_suppress_properties,
+};

plugins/obs-filters/obs-filters-config.h.in

+#pragma once
+
+#define SPEEXDSP_ENABLED @LIBSPEEXDSP_FOUND@

plugins/obs-filters/obs-filters.c

 #include <obs-module.h>
+#include "obs-filters-config.h"
 
 OBS_DECLARE_MODULE()
 
@@ -14,6 +15,9 @@ extern struct obs_source_info color_key_filter;
 extern struct obs_source_info sharpness_filter;
 extern struct obs_source_info chroma_key_filter;
 extern struct obs_source_info async_delay_filter;
+#ifdef SPEEXDSP_ENABLED
+extern struct obs_source_info noise_suppress_filter;
+#endif
 extern struct obs_source_info noise_gate_filter;
 
 bool obs_module_load(void)
@@ -28,6 +32,9 @@ bool obs_module_load(void)
 	obs_register_source(&sharpness_filter);
 	obs_register_source(&chroma_key_filter);
 	obs_register_source(&async_delay_filter);
+#ifdef SPEEXDSP_ENABLED
+	obs_register_source(&noise_suppress_filter);
+#endif
 	obs_register_source(&noise_gate_filter);
 	return true;
 }