Add new 'watch' effect.

Author: bmc0

GNUmakefile

@@ -22,6 +22,7 @@ DSP_OBJ := dsp.o \
 	noise.o \
 	dither.o \
 	stats.o \
+	watch.o \
 	null.o \
 	sgen.o \
 	pcm.o
@@ -42,20 +43,21 @@ LADSPA_DSP_OBJ := ladspa_dsp.o \
 	decorrelate.o \
 	noise.o \
 	dither.o \
-	stats.o
+	stats.o \
+	watch.o
 LADSPA_DSP_CPP_OBJ :=
 
-BASE_CFLAGS        := -Os -Wall -std=gnu99
-BASE_CXXFLAGS      := -Os -Wall -std=gnu++11
-BASE_LDFLAGS       :=
+BASE_CFLAGS        := -Os -Wall -std=gnu99 -pthread
+BASE_CXXFLAGS      := -Os -Wall -std=gnu++11 -pthread
+BASE_LDFLAGS       := -pthread
 BASE_LIBS          := -lm
 
 include config.mk
 
 DEPFLAGS            := -MMD -MP
-DSP_CFLAGS          := ${DEPFLAGS} ${BASE_CFLAGS} -pthread ${DSP_EXTRA_CFLAGS} ${CFLAGS} ${CPPFLAGS}
-DSP_CXXFLAGS        := ${DEPFLAGS} ${BASE_CXXFLAGS} -pthread ${DSP_EXTRA_CFLAGS} ${CXXFLAGS} ${CPPFLAGS}
-DSP_LDFLAGS         := ${BASE_LDFLAGS} -pthread ${LDFLAGS}
+DSP_CFLAGS          := ${DEPFLAGS} ${BASE_CFLAGS} ${DSP_EXTRA_CFLAGS} ${CFLAGS} ${CPPFLAGS}
+DSP_CXXFLAGS        := ${DEPFLAGS} ${BASE_CXXFLAGS} ${DSP_EXTRA_CFLAGS} ${CXXFLAGS} ${CPPFLAGS}
+DSP_LDFLAGS         := ${BASE_LDFLAGS} ${LDFLAGS}
 DSP_LIBS            := ${DSP_EXTRA_LIBS} ${BASE_LIBS}
 LADSPA_DSP_CFLAGS   := ${DEPFLAGS} ${BASE_CFLAGS} -fPIC -DPIC -DLADSPA_FRONTEND -DSYMMETRIC_IO ${LADSPA_DSP_EXTRA_CFLAGS} ${CFLAGS} ${CPPFLAGS}
 LADSPA_DSP_CXXFLAGS := ${DEPFLAGS} ${BASE_CXXFLAGS} -fPIC -DPIC -DLADSPA_FRONTEND -DSYMMETRIC_IO ${LADSPA_DSP_EXTRA_CFLAGS} ${CXXFLAGS} ${CPPFLAGS}

README.md

@@ -347,6 +347,27 @@ Example:
 	(dBFS), crest factor (dB), peak count, peak sample, number of samples, and
 	length (s) for each channel. If `ref_level` is given, peak and RMS levels
 	relative to `ref_level` will be shown as well (dBr).
+* `watch [-e] [~/]path`  
+	Load effects from a file into a sub-chain and reload if the file is
+	modified. Other than the automatic reload, the behavior is similar to
+	sourcing a file using the `@` directive (see "Effects Files"). Some
+	restrictions apply to automatic reload:
+
+	* The new sub-chain must have the same output sample rate and number of
+	  channels as the previous sub-chain.
+	* The new sub-chain must not require larger buffers than the previous
+	  sub-chain.
+
+	If these conditions are not met, the new sub-chain will not be applied and
+	an error message will be printed.
+
+	Currently, this effect polls for file modifications once per second.
+	Support `inotify` events my be added in the future. Ideally, file
+	modifications should be atomic (i.e. by writing to a temporary file, then
+	`rename(3)`-ing it over top of the original file). If this is not possible,
+	the `-e` flag may be given, which enforces an end-of-file marker in order
+	to detect partially-written files. This marker, `#EOF#`, must be placed at
+	the beginning of a line and may only be followed by whitespace characters.
 
 #### Selector syntax
 

dsp.1

@@ -373,6 +373,32 @@ Display the DC offset, minimum, maximum, peak level (dBFS), RMS level
 (dBFS), crest factor (dB), peak count, peak sample, number of samples, and
 length (s) for each channel. If \fIref_level\fR is given, peak and RMS levels
 relative to \fIref_level\fR will be shown as well (dBr).
+.TP
+\fBwatch\fR [\fI\-e\fR] [~/]\fIpath\fR
+Load effects from a file into a sub-chain and reload if the file is
+modified. Other than the automatic reload, the behavior is similar to
+sourcing a file using the `@' directive (see ``Effects Files''). Some
+restrictions apply to automatic reload:
+.RS
+.IP \(bu 3
+The new sub-chain must have the same output sample rate and number of
+channels as the previous sub-chain.
+.IP \(bu 3
+The new sub-chain must not require larger buffers than the previous
+sub-chain.
+.RE
+.TP
+\ 
+If these conditions are not met, the new sub-chain will not be applied and
+an error message will be printed.
+.sp 0.5
+Currently, this effect polls for file modifications once per second.
+Support `inotify` events my be added in the future. Ideally, file
+modifications should be atomic (i.e. by writing to a temporary file, then
+\fIrename\fR(3)-ing it over top of the original file). If this is not possible,
+the \fI\-e\fR flag may be given, which enforces an end-of-file marker in order
+to detect partially-written files. This marker, `#EOF#', must be placed at
+the beginning of a line and may only be followed by whitespace characters.
 .SS Selector syntax
 .TS
 tab (|);

effect.c

@@ -42,6 +42,7 @@
 #include "dither.h"
 #include "ladspa_host.h"
 #include "stats.h"
+#include "watch.h"
 
 #define DO_EFFECTS_CHAIN_OPTIMIZE 1
 
@@ -96,6 +97,7 @@ static const struct effect_info effects[] = {
 	{ "ladspa_host",        "ladspa_host module_path plugin_label [control ...]", ladspa_host_effect_init, 0 },
 #endif
 	{ "stats",              "stats [ref_level]",                       stats_effect_init,     0 },
+	{ "watch",              "watch [-e] [~/]path",                     watch_effect_init,     0 },
 };
 
 const struct effect_info * get_effect_info(const char *name)
@@ -127,7 +129,7 @@ void append_effect(struct effects_chain *chain, struct effect *e)
 }
 
 static int build_effects_chain_block(int, const char *const *, struct effects_chain *, struct stream_info *, const char *, const char *);
-static int build_effects_chain_from_file(struct effects_chain *, struct stream_info *, const char *, const char *, const char *);
+static int build_effects_chain_block_from_file(const char *, struct effects_chain *, struct stream_info *, const char *, const char *, int);
 
 static int build_effects_chain_block(int argc, const char *const *argv, struct effects_chain *chain, struct stream_info *stream, const char *initial_channel_mask, const char *dir)
 {
@@ -201,7 +203,7 @@ static int build_effects_chain_block(int argc, const char *const *argv, struct e
 			last_stream_channels = stream->channels;
 		}
 		if (argv[k][0] == '@') {
-			if (build_effects_chain_from_file(chain, stream, channel_selector, dir, &argv[k][1]))
+			if (build_effects_chain_block_from_file(&argv[k][1], chain, stream, channel_selector, dir, 0))
 				goto fail;
 			++k;
 			continue;
@@ -282,7 +284,7 @@ static int build_effects_chain_block(int argc, const char *const *argv, struct e
 	return 1;
 }
 
-static int build_effects_chain_from_file(struct effects_chain *chain, struct stream_info *stream, const char *channel_mask, const char *dir, const char *path)
+static int build_effects_chain_block_from_file(const char *path, struct effects_chain *chain, struct stream_info *stream, const char *channel_mask, const char *dir, int enforce_eof_marker)
 {
 	char **argv = NULL, *tmp, *d = NULL, *p, *c;
 	int i, ret = 0, argc = 0;
@@ -292,6 +294,15 @@ static int build_effects_chain_from_file(struct effects_chain *chain, struct str
 		LOG_FMT(LL_ERROR, "error: failed to load effects file: %s: %s", p, strerror(errno));
 		goto fail;
 	}
+	if (enforce_eof_marker) {
+		const ssize_t l = LENGTH(EFFECTS_FILE_EOF_MARKER)-1;
+		ssize_t k = strlen(c);
+		while (k > l && IS_WHITESPACE(c[k-1])) --k;
+		if (k < l || strncmp(&c[k-l], EFFECTS_FILE_EOF_MARKER, l) != 0 || (k > l && c[k-l-1] != '\n')) {
+			LOG_FMT(LL_ERROR, "error: no valid end-of-file marker: %s", p);
+			goto fail;
+		}
+	}
 	if (gen_argv_from_string(c, &argc, &argv))
 		goto fail;
 	d = strdup(p);
@@ -364,11 +375,19 @@ static void effects_chain_optimize(struct effects_chain *chain)
 #endif
 }
 
+
 int build_effects_chain(int argc, const char *const *argv, struct effects_chain *chain, struct stream_info *stream, const char *dir)
 {
-	int r;
-	if ((r = build_effects_chain_block(argc, argv, chain, stream, NULL, dir)))
-		return r;
+	int r = build_effects_chain_block(argc, argv, chain, stream, NULL, dir);
+	if (r) return r;
+	effects_chain_optimize(chain);
+	return 0;
+}
+
+int build_effects_chain_from_file(const char *path, struct effects_chain *chain, struct stream_info *stream, const char *channel_mask, const char *dir, int enforce_eof_marker)
+{
+	int r = build_effects_chain_block_from_file(path, chain, stream, channel_mask, dir, enforce_eof_marker);
+	if (r) return r;
 	effects_chain_optimize(chain);
 	return 0;
 }

effect.h

@@ -68,11 +68,13 @@ struct effects_chain {
 	|| strcmp(x, "!") == 0 \
 	|| strcmp(x, "{") == 0 \
 )
+#define EFFECTS_FILE_EOF_MARKER "#EOF#"
 
 const struct effect_info * get_effect_info(const char *);
 void destroy_effect(struct effect *);
 void append_effect(struct effects_chain *, struct effect *);
 int build_effects_chain(int, const char *const *, struct effects_chain *, struct stream_info *, const char *);
+int build_effects_chain_from_file(const char *, struct effects_chain *, struct stream_info *, const char *, const char *, int);
 ssize_t get_effects_chain_buffer_len(struct effects_chain *, ssize_t, int);
 ssize_t get_effects_chain_max_out_frames(struct effects_chain *, ssize_t);
 int effects_chain_needs_dither(struct effects_chain *);

ladspa_dsp.c

@@ -1,7 +1,7 @@
 /*
  * This file is part of dsp.
  *
- * Copyright (c) 2014-2024 Michael Barbour <[email protected]>
+ * Copyright (c) 2014-2025 Michael Barbour <[email protected]>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <signal.h>
+#include <pthread.h>
 #include <sys/types.h>
 #include <dirent.h>
 #include <errno.h>
@@ -57,9 +58,17 @@ struct dsp_globals dsp_globals = {
 static int n_configs = 0;
 static struct ladspa_dsp_config *configs = NULL;
 static LADSPA_Descriptor *descriptors = NULL;
+static pthread_mutex_t log_lock = PTHREAD_MUTEX_INITIALIZER;
 
-void dsp_log_acquire(void) { /* do nothing */ }
-void dsp_log_release(void) { /* do nothing */ }
+void dsp_log_acquire(void)
+{
+	pthread_mutex_lock(&log_lock);
+}
+
+void dsp_log_release(void)
+{
+	pthread_mutex_unlock(&log_lock);
+}
 
 static void init_config(struct ladspa_dsp_config *config, const char *file_name, const char *dir_path)
 {

util.c

@@ -1,7 +1,7 @@
 /*
  * This file is part of dsp.
  *
- * Copyright (c) 2013-2024 Michael Barbour <[email protected]>
+ * Copyright (c) 2013-2025 Michael Barbour <[email protected]>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -224,8 +224,6 @@ int num_bits_set(const char *b, int n)
 	return c;
 }
 
-#define IS_WHITESPACE(x) (x == ' ' || x == '\t' || x == '\n')
-
 static void strip_char(char *str, char c, int is_esc)
 {
 	int i = 0, k = 0, esc = 0;

util.h

@@ -1,7 +1,7 @@
 /*
  * This file is part of dsp.
  *
- * Copyright (c) 2013-2024 Michael Barbour <[email protected]>
+ * Copyright (c) 2013-2025 Michael Barbour <[email protected]>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -52,6 +52,7 @@
 #endif
 #define TEST_BIT(x, o, s) (!!GET_BIT(x, o) == !!(s))
 #define IS_POWER_OF_2(x) ((x) && !((x)&((x)-1)))
+#define IS_WHITESPACE(x) ((x) == ' ' || (x) == '\t' || (x) == '\n' || (x) == '\r')
 #define PM_RAND_MAX 0x7fffffff
 
 int check_endptr(const char *, const char *, const char *, const char *);