output/recorder: new output plugin for recording radio streams

The recorder plugin writes audio played by MPD to a file.  This may be
useful for recording radio streams.

This implementation is incomplete, because support for tags is
missing, and MPD should be able to record each track to a different
file.

Makefile.am

@@ -597,6 +597,10 @@ if HAVE_SHOUT
 OUTPUT_SRC += src/output/shout_plugin.c
 endif
 
+if ENABLE_RECORDER_OUTPUT
+OUTPUT_SRC += src/output/recorder_output_plugin.c
+endif
+
 if ENABLE_HTTPD_OUTPUT
 OUTPUT_SRC += \
 	src/icy_server.c \

NEWS

@@ -15,6 +15,8 @@ ver 0.16 (20??/??/??)
   - flac: load external cue sheet when no internal one
 * encoders:
   - twolame: new encoder plugin based on libtwolame
+* output:
+  - recorder: new output plugin for recording radio streams
 * mixers:
   - removed support for legacy mixer configuration
   - reimplemented software volume as mixer+filter plugin

configure.ac

@@ -708,6 +708,11 @@ fi
 
 AM_CONDITIONAL(HAVE_PULSE, test x$enable_pulse = xyes)
 
+AC_ARG_ENABLE(recorder-output,
+	AS_HELP_STRING([--enable-recorder-output],
+		[enables the HTTP server output]),,
+	[enable_recorder_output=auto])
+
 AC_ARG_ENABLE(httpd-output,
 	AS_HELP_STRING([--enable-httpd-output],
 		[enables the HTTP server output]),,
@@ -992,10 +997,14 @@ dnl
 dnl Encoder API and shout/httpd output plugin
 dnl
 
-if test x$enable_shout = xyes || test x$enable_httpd_output = xyes; then
+if test x$enable_shout = xyes || \
+	test x$enable_recorder_output = xyes || \
+	test x$enable_httpd_output = xyes; then
 	# at least one output using encoders is explicitly enabled
 	need_encoder=yes
-elif test x$enable_shout = xauto || test x$enable_httpd_output = xauto; then
+elif test x$enable_shout = xauto || \
+	test x$enable_recorder_output = xauto || \
+	test x$enable_httpd_output = xauto; then
 	need_encoder=auto
 else
 	# all outputs using encoders are disabled
@@ -1048,6 +1057,17 @@ if test x$enable_shout = xauto; then
 	fi
 fi
 
+if test x$enable_recorder_output = xauto; then
+	# handle recorder auto-detection: disable if no encoder is
+	# available
+	if test x$enable_encoder = xyes; then
+		enable_recorder_output=yes
+	else
+		AC_MSG_WARN([No encoder plugin -- disabling the recorder output plugin])
+		enable_recorder_output=no
+	fi
+fi
+
 if test x$enable_httpd_output = xauto; then
 	# handle HTTPD auto-detection: disable if no encoder is
 	# available
@@ -1064,6 +1084,11 @@ if test x$enable_shout = xyes; then
 	AC_DEFINE(HAVE_SHOUT, 1, [Define to enable the shoutcast output])
 fi
 
+AM_CONDITIONAL(ENABLE_RECORDER_OUTPUT, test x$enable_recorder_output = xyes)
+if test x$enable_recorder_output = xyes; then
+	AC_DEFINE(ENABLE_RECORDER_OUTPUT, 1, [Define to enable the recorder output])
+fi
+
 AM_CONDITIONAL(ENABLE_HTTPD_OUTPUT, test x$enable_httpd_output = xyes)
 if test x$enable_httpd_output = xyes; then
 	AC_DEFINE(ENABLE_HTTPD_OUTPUT, 1, [Define to enable the HTTP server output])
@@ -1225,6 +1250,12 @@ else
 	echo " FIFO support ..................disabled"
 fi
 
+if test x$enable_recorder_output = xyes; then
+	echo " recorder support ..............enabled"
+else
+	echo " recorder support ..............disabled"
+fi
+
 if test x$enable_httpd_output = xyes; then
 	echo " HTTP daemon support ...........enabled"
 else
@@ -1291,6 +1322,7 @@ if
 	test x$enable_ao = xno &&
 	test x$enable_oss = xno &&
 	test x$enable_shout = xno &&
+	test x$enable_recorder_output = xno &&
 	test x$enable_httpd_output = xno &&
 	test x$enable_solaris_output = xno &&
 	test x$enable_alsa = xno &&
@@ -1305,6 +1337,7 @@ fi
 
 if
 	test x$enable_shout = xyes ||
+	test x$enable_recorder = xyes ||
 	test x$enable_httpd_output = xyes; then
 		echo " Streaming Encoder Support:"
 		if test x$enable_lame_encoder = xyes; then

doc/mpdconf.example

@@ -226,6 +226,18 @@ input {
 #	mixer_type      "software"		# optional
 #}
 #
+# An example of a recorder output:
+#
+#audio_output {
+#	type		"recorder"
+#	name		"My recorder"
+#	encoder		"vorbis"		# optional, vorbis or lame
+#	path		"/var/lib/mpd/recorder/mpd.ogg"
+#	quality		"5.0"			# do not define if bitrate is defined
+#	bitrate		"128"			# do not define if quality is defined
+#	format		"44100:16:1"
+#}
+#
 # An example of a httpd output (built-in HTTP streaming server):
 #
 #audio_output {

doc/user.xml

@@ -834,6 +834,73 @@ cd mpd-version</programlisting>
         </informaltable>
       </section>
 
+      <section>
+        <title><varname>recorder</varname></title>
+
+        <para>
+          The <varname>recorder</varname> plugin writes the audio
+          played by MPD to a file.  This may be useful for recording
+          radio streams.
+        </para>
+
+        <para>
+          You must configure either <varname>quality</varname> or
+          <varname>bitrate</varname>.
+        </para>
+
+        <informaltable>
+          <tgroup cols="2">
+            <thead>
+              <row>
+                <entry>Setting</entry>
+                <entry>Description</entry>
+              </row>
+            </thead>
+            <tbody>
+              <row>
+                <entry>
+                  <varname>path</varname>
+                  <parameter>P</parameter>
+                </entry>
+                <entry>
+                  Write to this file.
+                </entry>
+              </row>
+              <row>
+                <entry>
+                  <varname>encoder</varname>
+                  <parameter>NAME</parameter>
+                </entry>
+                <entry>
+                  Chooses an encoder plugin,
+                  e.g. <parameter>vorbis</parameter>.
+                </entry>
+              </row>
+              <row>
+                <entry>
+                  <varname>quality</varname>
+                  <parameter>Q</parameter>
+                </entry>
+                <entry>
+                  Configures the encoder quality (for VBR) in the
+                  range -1 .. 10.
+                </entry>
+              </row>
+              <row>
+                <entry>
+                  <varname>bitrate</varname>
+                  <parameter>BR</parameter>
+                </entry>
+                <entry>
+                  Sets a constant encoder bit rate, in kilobit per
+                  second.
+                </entry>
+              </row>
+            </tbody>
+          </tgroup>
+        </informaltable>
+      </section>
+
       <section>
         <title><varname>shout</varname></title>
 

src/output/recorder_output_plugin.c

@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "output_api.h"
+#include "encoder_plugin.h"
+#include "encoder_list.h"
+
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "recorder"
+
+struct recorder_output {
+	/**
+	 * The configured encoder plugin.
+	 */
+	struct encoder *encoder;
+
+	/**
+	 * The destination file name.
+	 */
+	const char *path;
+
+	/**
+	 * The destination file descriptor.
+	 */
+	int fd;
+
+	/**
+	 * The buffer for encoder_read().
+	 */
+	char buffer[32768];
+};
+
+/**
+ * The quark used for GError.domain.
+ */
+static inline GQuark
+recorder_output_quark(void)
+{
+	return g_quark_from_static_string("recorder_output");
+}
+
+static void *
+recorder_output_init(G_GNUC_UNUSED const struct audio_format *audio_format,
+		     const struct config_param *param, GError **error_r)
+{
+	struct recorder_output *recorder = g_new(struct recorder_output, 1);
+	const char *encoder_name;
+	const struct encoder_plugin *encoder_plugin;
+
+	/* read configuration */
+
+	encoder_name = config_get_block_string(param, "encoder", "vorbis");
+	encoder_plugin = encoder_plugin_get(encoder_name);
+	if (encoder_plugin == NULL) {
+		g_set_error(error_r, recorder_output_quark(), 0,
+			    "No such encoder: %s", encoder_name);
+		return NULL;
+	}
+
+	recorder->path = config_get_block_string(param, "path", NULL);
+	if (recorder->path == NULL) {
+		g_set_error(error_r, recorder_output_quark(), 0,
+			    "'path' not configured");
+		return NULL;
+	}
+
+	/* initialize encoder */
+
+	recorder->encoder = encoder_init(encoder_plugin, param, error_r);
+	if (recorder->encoder == NULL)
+		return NULL;
+
+	return recorder;
+}
+
+static void
+recorder_output_finish(void *data)
+{
+	struct recorder_output *recorder = data;
+
+	encoder_finish(recorder->encoder);
+	g_free(recorder);
+}
+
+/**
+ * Writes pending data from the encoder to the output file.
+ */
+static bool
+recorder_output_encoder_to_file(struct recorder_output *recorder,
+			      GError **error_r)
+{
+	size_t size = 0, position, nbytes;
+
+	assert(recorder->fd >= 0);
+
+	/* read from the encoder */
+
+	size = encoder_read(recorder->encoder, recorder->buffer,
+			    sizeof(recorder->buffer));
+	if (size == 0)
+		return true;
+
+	/* write everything into the file */
+
+	position = 0;
+	while (true) {
+		nbytes = write(recorder->fd, recorder->buffer + position,
+			       size - position);
+		if (nbytes > 0) {
+			position += (size_t)nbytes;
+			if (position >= size)
+				return true;
+		} else if (nbytes == 0) {
+			/* shouldn't happen for files */
+			g_set_error(error_r, recorder_output_quark(), 0,
+				    "write() returned 0");
+			return false;
+		} else if (errno != EINTR) {
+			g_set_error(error_r, recorder_output_quark(), 0,
+				    "Failed to write to '%s': %s",
+				    recorder->path, g_strerror(errno));
+			return false;
+		}
+	}
+}
+
+static bool
+recorder_output_open(void *data, struct audio_format *audio_format,
+		     GError **error_r)
+{
+	struct recorder_output *recorder = data;
+	bool success;
+
+	/* create the output file */
+
+	recorder->fd = creat(recorder->path, 0666);
+	if (recorder->fd < 0) {
+		g_set_error(error_r, recorder_output_quark(), 0,
+			    "Failed to create '%s': %s",
+			    recorder->path, g_strerror(errno));
+		return false;
+	}
+
+	/* open the encoder */
+
+	success = encoder_open(recorder->encoder, audio_format, error_r);
+	if (!success) {
+		close(recorder->fd);
+		unlink(recorder->path);
+		return false;
+	}
+
+	return true;
+}
+
+static void
+recorder_output_close(void *data)
+{
+	struct recorder_output *recorder = data;
+
+	/* flush the encoder and write the rest to the file */
+
+	if (encoder_flush(recorder->encoder, NULL))
+		recorder_output_encoder_to_file(recorder, NULL);
+
+	/* now really close everything */
+
+	encoder_close(recorder->encoder);
+
+	close(recorder->fd);
+}
+
+static size_t
+recorder_output_play(void *data, const void *chunk, size_t size,
+		     GError **error_r)
+{
+	struct recorder_output *recorder = data;
+
+	return encoder_write(recorder->encoder, chunk, size, error_r) &&
+		recorder_output_encoder_to_file(recorder, error_r)
+		? size : 0;
+}
+
+const struct audio_output_plugin recorder_output_plugin = {
+	.name = "recorder",
+	.init = recorder_output_init,
+	.finish = recorder_output_finish,
+	.open = recorder_output_open,
+	.close = recorder_output_close,
+	.play = recorder_output_play,
+};

src/output_list.c

@@ -34,6 +34,7 @@ extern const struct audio_output_plugin pulse_plugin;
 extern const struct audio_output_plugin mvp_output_plugin;
 extern const struct audio_output_plugin jackPlugin;
 extern const struct audio_output_plugin httpd_output_plugin;
+extern const struct audio_output_plugin recorder_output_plugin;
 
 const struct audio_output_plugin *audio_output_plugins[] = {
 #ifdef HAVE_SHOUT
@@ -72,6 +73,9 @@ const struct audio_output_plugin *audio_output_plugins[] = {
 #endif
 #ifdef ENABLE_HTTPD_OUTPUT
 	&httpd_output_plugin,
+#endif
+#ifdef ENABLE_RECORDER_OUTPUT
+	&recorder_output_plugin,
 #endif
 	NULL
 };