filter: added the "autoconvert" filter plugin

Makefile.am

@@ -50,6 +50,7 @@ mpd_headers = \
 	src/filter_config.h \
 	src/filter_plugin.h \
 	src/filter_registry.h \
+	src/filter/autoconvert_filter_plugin.h \
 	src/filter/chain_filter_plugin.h \
 	src/filter/convert_filter_plugin.h \
 	src/filter/volume_filter_plugin.h \
@@ -720,6 +721,7 @@ endif
 FILTER_SRC = \
 	src/filter/null_filter_plugin.c \
 	src/filter/chain_filter_plugin.c \
+	src/filter/autoconvert_filter_plugin.c \
 	src/filter/convert_filter_plugin.c \
 	src/filter/route_filter_plugin.c \
 	src/filter/normalize_filter_plugin.c \

src/filter/autoconvert_filter_plugin.c

@@ -0,0 +1,169 @@
+/*
+ * 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 "config.h"
+#include "filter/autoconvert_filter_plugin.h"
+#include "filter/convert_filter_plugin.h"
+#include "filter_plugin.h"
+#include "filter_internal.h"
+#include "filter_registry.h"
+#include "conf.h"
+#include "pcm_convert.h"
+#include "audio_format.h"
+#include "poison.h"
+
+#include <assert.h>
+#include <string.h>
+
+struct autoconvert_filter {
+	struct filter base;
+
+	/**
+	 * The audio format being fed to the underlying filter.  This
+	 * plugin actually doesn't need this variable, we have it here
+	 * just so our open() method doesn't return a stack pointer.
+	 */
+	struct audio_format in_audio_format;
+
+	/**
+	 * The underlying filter.
+	 */
+	struct filter *filter;
+
+	/**
+	 * A convert_filter, just in case conversion is needed.  NULL
+	 * if unused.
+	 */
+	struct filter *convert;
+};
+
+static void
+autoconvert_filter_finish(struct filter *_filter)
+{
+	struct autoconvert_filter *filter =
+		(struct autoconvert_filter *)_filter;
+
+	filter_free(filter->filter);
+	g_free(filter);
+}
+
+static const struct audio_format *
+autoconvert_filter_open(struct filter *_filter,
+			struct audio_format *in_audio_format,
+			GError **error_r)
+{
+	struct autoconvert_filter *filter =
+		(struct autoconvert_filter *)_filter;
+	const struct audio_format *out_audio_format;
+
+	assert(audio_format_valid(in_audio_format));
+
+	/* open the "real" filter */
+
+	filter->in_audio_format = *in_audio_format;
+
+	out_audio_format = filter_open(filter->filter,
+				       &filter->in_audio_format, error_r);
+	if (out_audio_format == NULL)
+		return NULL;
+
+	/* need to convert? */
+
+	if (!audio_format_equals(&filter->in_audio_format, in_audio_format)) {
+		/* yes - create a convert_filter */
+		struct audio_format audio_format2 = *in_audio_format;
+		const struct audio_format *audio_format3;
+
+		filter->convert = filter_new(&convert_filter_plugin, NULL,
+					     error_r);
+		if (filter->convert == NULL) {
+			filter_close(filter->filter);
+			return NULL;
+		}
+
+		audio_format3 = filter_open(filter->convert, &audio_format2,
+					    error_r);
+		if (audio_format3 == NULL) {
+			filter_free(filter->convert);
+			filter_close(filter->filter);
+			return NULL;
+		}
+
+		assert(audio_format_equals(&audio_format2, in_audio_format));
+
+		convert_filter_set(filter->convert, &filter->in_audio_format);
+	} else
+		/* no */
+		filter->convert = NULL;
+
+	return out_audio_format;
+}
+
+static void
+autoconvert_filter_close(struct filter *_filter)
+{
+	struct autoconvert_filter *filter =
+		(struct autoconvert_filter *)_filter;
+
+	if (filter->convert != NULL) {
+		filter_close(filter->convert);
+		filter_free(filter->convert);
+	}
+
+	filter_close(filter->filter);
+}
+
+static const void *
+autoconvert_filter_filter(struct filter *_filter, const void *src,
+			  size_t src_size, size_t *dest_size_r,
+			  GError **error_r)
+{
+	struct autoconvert_filter *filter =
+		(struct autoconvert_filter *)_filter;
+
+	if (filter->convert != NULL) {
+		src = filter_filter(filter->convert, src, src_size, &src_size,
+				    error_r);
+		if (src == NULL)
+			return NULL;
+	}
+
+	return filter_filter(filter->filter, src, src_size, dest_size_r,
+			     error_r);
+}
+
+static const struct filter_plugin autoconvert_filter_plugin = {
+	.name = "convert",
+	.finish = autoconvert_filter_finish,
+	.open = autoconvert_filter_open,
+	.close = autoconvert_filter_close,
+	.filter = autoconvert_filter_filter,
+};
+
+struct filter *
+autoconvert_filter_new(struct filter *_filter)
+{
+	struct autoconvert_filter *filter =
+		g_new(struct autoconvert_filter, 1);
+
+	filter_init(&filter->base, &autoconvert_filter_plugin);
+	filter->filter = _filter;
+
+	return &filter->base;
+}

src/filter/autoconvert_filter_plugin.h

@@ -0,0 +1,34 @@
+/*
+ * 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.
+ */
+
+#ifndef AUTOCONVERT_FILTER_PLUGIN_H
+#define AUTOCONVERT_FILTER_PLUGIN_H
+
+struct filter;
+
+/**
+ * Creates a new "autoconvert" filter.  When opened, it ensures that
+ * the input audio format isn't changed.  If the underlying filter
+ * requests a different format, it automatically creates a
+ * convert_filter.
+ */
+struct filter *
+autoconvert_filter_new(struct filter *filter);
+
+#endif