1 files changed, 96 insertions, 0 deletions
diff --git a/tutorials/sndkit/tests/synctest.c b/tutorials/sndkit/tests/synctest.c
new file mode 100644
index 0000000..d2ed77b
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+++ b/tutorials/sndkit/tests/synctest.c
@@ -0,0 +1,96 @@
+/*
+ * Purpose: A program that demonstrates use of syncronization groups.
+ * Copyright (C) 4Front Technologies, 2002-2004. Released under GPLv2/CDDL.
+ *
+ * Description:
+ * This program opens three audio devices (hard coded in the program)
+ * and creates a syncronization group using {!nlink SNDCTL_DSP_SYNCGROUP}.
+ * 
+ * Next it starts all the devices joined in the group simultaneously
+ * by calling {!nlink SNDCTL_DSP_SYNCSTART}. Finally it will keep copying
+ * audio input from the 3rd device to the other two ones.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <soundcard.h>
+
+#define MAX_DEV		10
+
+int
+main (int argc, char *argv[])
+{
+  int i, id, fd[MAX_DEV], ndevs = 0;
+  char buf[32768] = { 0 };
+
+  oss_syncgroup group;
+
+  group.id = 0;
+  group.mode = PCM_ENABLE_OUTPUT;
+
+/*
+ * Open the devices listed on command line
+ */
+  if (argc < 2)
+    exit (-1);
+
+  for (i = 1; i < argc; i++)
+    {
+      if ((fd[ndevs] = open (argv[i], O_WRONLY, 0)) == -1)
+	{
+	  perror (argv[i]);
+	  exit (-1);
+	}
+
+      if (ioctl (fd[ndevs], SNDCTL_DSP_SYNCGROUP, &group) == -1)
+	{
+	  perror ("SNDCTL_DSP_SYNCGROUP");
+	  exit (-1);
+	}
+/*
+ * Note! It is very important to write some data to all output devices
+ * between calling SNDCTL_DSP_SYNCGROUP and SNDCTL_DSP_SYNCSTART. Otherwise
+ * playback will not start properly. However do not write more data than
+ * there is room in device's DMA buffer. Recommended amount of prteload data
+ * is one full fragment.
+ *
+ * In applications that record audio, process it and then play back it's
+ * necessary to write two fragments of silence to the output device(s) before
+ * starting the group. Otherwise output device(s) will run out of data before
+ * the first read from the input device returns.
+ */
+
+      if (write (fd[ndevs], buf, sizeof (buf)) != sizeof (buf))
+	{
+	  perror ("write");
+	  exit (-1);
+	}
+
+      ndevs++;
+    }
+
+  printf ("Sync group %x created with %d devices\n", group.id, ndevs);
+
+
+  id = group.id;
+
+  if (ioctl (fd[0], SNDCTL_DSP_SYNCSTART, &id) == -1)
+    {
+      perror ("SNDCTL_DSP_SYNCSTART");
+      exit (-1);
+    }
+
+  while (1)
+    {
+      for (i = 0; i < ndevs; i++)
+	if (write (fd[i], buf, sizeof (buf)) != sizeof (buf))
+	  {
+	    perror ("write2");
+	    exit (-1);
+	  }
+    }
+
+  exit (0);
+}