Add new auidio back end -- to stdout.

audio_stdout.c

@@ -0,0 +1,101 @@
+/*
+ * pipe output driver. This file is part of Shairport.
+ * Copyright (c) James Laird 2013
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <memory.h>
+#include <stdlib.h>
+#include <errno.h>
+#include "common.h"
+#include "audio.h"
+
+static int fd = -1;
+
+static void start(int sample_rate) {
+  fd = STDOUT_FILENO;
+}
+
+static void play(short buf[], int samples) {
+  int ignore = write(fd, buf, samples * 4);
+}
+
+static void stop(void) {
+  // don't close stdout
+}
+
+static int init(int argc, char **argv) {
+  const char *str;
+  int value;
+
+  config.audio_backend_buffer_desired_length = 44100; // one second.
+  config.audio_backend_latency_offset = 0;
+
+  if (config.cfg != NULL) {
+    /* Get the desired buffer size setting. */
+    debug(1,"Get buffer length");
+    if (config_lookup_int(config.cfg, "stdout.audio_backend_buffer_desired_length", &value)) {
+      if ((value < 0) || (value > 132300))
+        die("Invalid stdout audio backend buffer desired length \"%d\". It should be between 0 and 132300, default is 44100",
+            value);
+      else
+        config.audio_backend_buffer_desired_length = value;
+    }
+
+    /* Get the latency offset. */
+    debug(1,"Get latency");
+    if (config_lookup_int(config.cfg, "stdout.audio_backend_latency_offset", &value)) {
+      debug(1,"Got a latency value of %d.",value);
+      if ((value < -66150) || (value > 66150))
+        die("Invalid stdout audio backend buffer latency offset \"%d\". It should be between -66150 and +66150, default is 0",
+            value);
+      else
+        config.audio_backend_latency_offset = value;
+    }
+  }
+  debug(1,"buffer: %d, latency: %d.",config.audio_backend_buffer_desired_length,config.audio_backend_latency_offset);
+  return 0;
+}
+
+static void deinit(void) {
+  // don't close stdout
+}
+
+static void help(void) {
+  printf("    stdout takes no arguments\n");
+}
+
+audio_output audio_stdout = {.name = "stdout",
+                           .help = &help,
+                           .init = &init,
+                           .deinit = &deinit,
+                           .start = &start,
+                           .stop = &stop,
+                           .flush = NULL,
+                           .delay = NULL,
+                           .play = &play,
+                           .volume = NULL,
+                           .parameters = NULL};