added silence audio filter

Makefile.in

@@ -123,6 +123,7 @@ COMMON_OBJS     = \
 		src/audio/filter/delay.o \
 		src/audio/filter/discard.o \
 		src/audio/filter/controlport_stats.o \
+		src/audio/filter/silence.o \
 		src/capture_filter.o \
 		src/capture_filter/change_pixfmt.o \
 		src/capture_filter/color.o \

src/audio/audio_filter.h

@@ -64,7 +64,7 @@ struct audio_filter_info{
         /// @retval     0      if initialized successfully
         /// @retval     <0     if error
         /// @retval     >0     no error but state was not returned, eg. showing help
-        af_result_code (*init)(struct module *mod, const char *cfg, void **state);
+        enum af_result_code (*init)(struct module *mod, const char *cfg, void **state);
 
         /// @brief Frees filter
         void (*done)(void *state);
@@ -76,7 +76,7 @@ struct audio_filter_info{
         /// @param sample_rate   sample rate
         /// @retval  0                      if initialized successfully
         /// @retval  <0                     if error
-        af_result_code (*configure)(void *state,
+        enum af_result_code (*configure)(void *state,
                         int bps, int ch_count, int sample_rate);
 
         /// @brief Get configured input audio format
@@ -91,20 +91,20 @@ struct audio_filter_info{
         /// @param state         filter state
         /// @param f             frame to filter, can take ownership of passed
 		//                       frame and return a different one
-        af_result_code (*filter)(void *state, struct audio_frame **f);
+        enum af_result_code (*filter)(void *state, struct audio_frame **f);
 };
 
 struct audio_filter{
         const struct audio_filter_info *info;
         void *state;
 };
 
-af_result_code audio_filter_init(struct module *parent, const char *name, const char *cfg,
+enum af_result_code audio_filter_init(struct module *parent, const char *name, const char *cfg,
                 struct audio_filter *filter);
 
 void audio_filter_destroy(struct audio_filter *state);
 
-af_result_code audio_filter_configure(struct audio_filter *state,
+enum af_result_code audio_filter_configure(struct audio_filter *state,
                 int bps, int ch_count, int sample_rate);
 
 void audio_filter_get_configured_out(struct audio_filter *state,
@@ -113,7 +113,7 @@ void audio_filter_get_configured_out(struct audio_filter *state,
 void audio_filter_get_configured_in(struct audio_filter *state,
                 int *bps, int *ch_count, int *sample_rate);
 
-af_result_code audio_filter(struct audio_filter *state, struct audio_frame **frame);
+enum af_result_code audio_filter(struct audio_filter *state, struct audio_frame **frame);
 
 //void register_audio_filter(struct audio_filter_info *filter);
 

src/audio/filter/silence.c

@@ -0,0 +1,159 @@
+/**
+ * @file   audio/filter/silence.c
+ * @author Martin Pulec <[email protected]>
+ */
+/*
+ * Copyright (c) 2023 CESNET, z. s. p. o.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, is permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of CESNET nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "audio/audio_filter.h"
+#include "audio/types.h"
+#include "lib_common.h"
+#include "utils/color_out.h"
+
+enum {
+        MAX_CHANNELS = 16,
+};
+
+struct state_silence {
+        struct audio_desc desc;
+        size_t silence_channels[MAX_CHANNELS];
+        int silence_channels_count;
+};
+
+static void
+usage()
+{
+        color_printf("Audio capture " TBOLD(
+            "silence") " allows muting individual channels.\n\n");
+        color_printf("Usage:\n");
+        color_printf("\t" TBOLD("--audio-filter silence[:<idx1>,<idx2>]\n\n"));
+        color_printf("(indexed from zero)\n");
+        color_printf("If no index is given, all channels will be muted.\n");
+}
+
+static enum af_result_code
+init(struct module *parent, const char *cfg, void **state)
+{
+        (void) parent;
+        if (strlen(cfg) > 0) {
+                cfg++;
+        }
+        if (strcmp(cfg, "help") == 0) {
+                usage();
+                return AF_HELP_SHOWN;
+        }
+        struct state_silence *s = calloc(1, sizeof *s);
+
+        char *fmt     = strdupa(cfg);
+        char *item    = NULL;
+        char *end_ptr = NULL;
+        while ((item = strtok_r(fmt, ",", &end_ptr)) != NULL) {
+                assert(s->silence_channels_count < MAX_CHANNELS - 1);
+                s->silence_channels[s->silence_channels_count++] =
+                    strtol(item, NULL, 10);
+                fmt = NULL;
+        }
+        *state = s;
+        return AF_OK;
+}
+
+static enum af_result_code
+configure(void *state, int in_bps, int in_ch_count, int in_sample_rate)
+{
+        struct state_silence *s = state;
+
+        s->desc.bps         = in_bps;
+        s->desc.ch_count    = in_ch_count;
+        s->desc.sample_rate = in_sample_rate;
+        return AF_OK;
+}
+
+static void
+done(void *state)
+{
+        free(state);
+}
+
+static void
+get_configured_desc(void *state, int *bps, int *ch_count, int *sample_rate)
+{
+        struct state_silence *s = state;
+
+        *bps         = s->desc.bps;
+        *ch_count    = s->desc.ch_count;
+        *sample_rate = s->desc.sample_rate;
+}
+
+static enum af_result_code
+filter(void *state, struct audio_frame **frame)
+{
+        struct state_silence *s = state;
+
+        if (s->silence_channels_count == 0) {
+                memset((*frame)->data, 0, (*frame)->data_len);
+                return AF_OK;
+        }
+
+        const int frame_size = s->desc.bps * s->desc.ch_count;
+        for (int i = 0; i < s->silence_channels_count; ++i) {
+                if (s->silence_channels[i] >= (size_t) (*frame)->ch_count) {
+                        continue;
+                }
+                char *ptr =
+                    (*frame)->data + s->silence_channels[i] * (*frame)->bps;
+                for (int j = 0; j < (*frame)->data_len; j += frame_size) {
+                        memset(ptr, 0, (*frame)->bps);
+                        ptr += frame_size;
+                }
+        }
+
+        return AF_OK;
+}
+
+static const struct audio_filter_info audio_filter_silence = {
+        .name               = "silence",
+        .init               = init,
+        .done               = done,
+        .configure          = configure,
+        .get_configured_in  = get_configured_desc,
+        .get_configured_out = get_configured_desc,
+        .filter             = filter,
+};
+
+REGISTER_MODULE(silence, &audio_filter_silence, LIBRARY_CLASS_AUDIO_FILTER,
+                AUDIO_FILTER_ABI_VERSION);