Add option to decode raw audio data from STDIN

CMakeLists.txt

@@ -3,7 +3,7 @@ project (acarsdec C)
 
 add_compile_options(-Ofast -march=native)
 
-add_executable(acarsdec acars.c  acarsdec.c  cJSON.c  label.c  msk.c  output.c netout.c fileout.c )
+add_executable(acarsdec acars.c  acarsdec.c  cJSON.c  label.c  msk.c  output.c netout.c fileout.c stdin.c )
 
 find_package(PkgConfig)
 if(PKG_CONFIG_FOUND)

acarsdec.c

@@ -97,6 +97,8 @@ static void usage(void)
 #ifdef HAVE_LIBACARS
 	fprintf(stderr, " [--skip-reassembly] ");
 #endif
+	fprintf(stderr,
+		"-s |");
 #ifdef WITH_MQTT
 	fprintf(stderr, " [ -M mqtt_url");
 	fprintf(stderr, " [-T mqtt_topic] |");
@@ -159,6 +161,8 @@ static void usage(void)
 	fprintf(stderr, " -P mqtt_passwd\t\t: Optional MQTT password\n");
 #endif
 	fprintf(stderr, "\n");
+	fprintf(stderr,
+		" -s\t\t\t: decode from a raw audio stream on STDIN (sample rate: %d; sample format: F32)\n",INTRATE);
 
 #ifdef WITH_ALSA
 	fprintf(stderr,
@@ -262,6 +266,10 @@ int main(int argc, char **argv)
 			skip_reassembly = 1;
 			break;
 #endif
+        case 's':
+            res = initStdIn(argv, optind);
+            inmode = 7;
+            break;
 #ifdef WITH_ALSA
 		case 'a':
 			res = initAlsa(argv, optind);
@@ -391,7 +399,7 @@ int main(int argc, char **argv)
 	}
 
 	if (inmode == 0) {
-		fprintf(stderr, "Need at least one of -a|-f|-r|-R|-d options\n");
+		fprintf(stderr, "Need at least one of -s|-a|-f|-r|-R|-d options\n");
 		usage();
 	}
 
@@ -501,6 +509,9 @@ int main(int argc, char **argv)
 		res = runSoapyClose();
 		break;
 #endif
+    case 7:
+        runStdInSample();
+        break;
 	default:
 		res = -1;
 	}

acarsdec.h

@@ -149,6 +149,8 @@ extern int initOutput(char*,char *);
 #ifdef HAVE_LIBACARS
 extern int skip_reassembly;
 #endif
+extern int initStdIn(char **argv,int optind);
+extern int runStdInSample(void);
 #ifdef WITH_ALSA
 extern int initAlsa(char **argv,int optind);
 extern int runAlsaSample(void);

stdin.c

@@ -0,0 +1,47 @@
+/*
+ *  Copyright (c) 2023 Jakob Ketterl
+ *
+ *
+ *   This code is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Library General Public License version 2
+ *   published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Library General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Library General Public
+ *   License along with this library; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include "acarsdec.h"
+#include <unistd.h>
+#include <malloc.h>
+
+#define MAX_SAMPLES 1024
+
+int initStdIn(char **argv,int optind) {
+    nbch = 1;
+    channel[0].dm_buffer=malloc(sizeof(sample_t)*MAX_SAMPLES);
+    return 0;
+}
+
+int runStdInSample(void) {
+    ssize_t nbi;
+
+    do {
+        nbi = read(STDIN_FILENO, channel[0].dm_buffer, sizeof(sample_t) * MAX_SAMPLES);
+
+        if (nbi <= 0) {
+            return -1;
+        }
+
+        demodMSK(&(channel[0]), nbi / sizeof(sample_t));
+
+    } while (1);
+
+    return 0;
+}