decoder/mad: move RVA2 code to tag_rva2.c

1 files changed, 110 insertions, 0 deletions

diff --git a/src/tag_rva2.c b/src/tag_rva2.c
new file mode 100644
index 00000000..28002025
--- /dev/null
+++ b/src/tag_rva2.c
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2003-2010 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 "tag_rva2.h"
+#include "replay_gain_info.h"
+
+#include <glib.h>
+#include <id3tag.h>
+
+bool
+tag_rva2_parse(struct id3_tag *tag, struct replay_gain_info *replay_gain_info)
+{
+	struct id3_frame const * frame;
+
+	id3_latin1_t const *id;
+	id3_byte_t const *data;
+	id3_length_t length;
+
+	enum {
+		CHANNEL_OTHER         = 0x00,
+		CHANNEL_MASTER_VOLUME = 0x01,
+		CHANNEL_FRONT_RIGHT   = 0x02,
+		CHANNEL_FRONT_LEFT    = 0x03,
+		CHANNEL_BACK_RIGHT    = 0x04,
+		CHANNEL_BACK_LEFT     = 0x05,
+		CHANNEL_FRONT_CENTRE  = 0x06,
+		CHANNEL_BACK_CENTRE   = 0x07,
+		CHANNEL_SUBWOOFER     = 0x08
+	};
+
+	/* relative volume adjustment information */
+
+	frame = id3_tag_findframe(tag, "RVA2", 0);
+	if (frame == NULL)
+		return false;
+
+	id   = id3_field_getlatin1(id3_frame_field(frame, 0));
+	data = id3_field_getbinarydata(id3_frame_field(frame, 1),
+					&length);
+
+	if (id == NULL || data == NULL)
+		return false;
+
+	/*
+	 * "The 'identification' string is used to identify the
+	 * situation and/or device where this adjustment should apply.
+	 * The following is then repeated for every channel
+	 *
+	 *   Type of channel         $xx
+	 *   Volume adjustment       $xx xx
+	 *   Bits representing peak  $xx
+	 *   Peak volume             $xx (xx ...)"
+	 */
+
+	while (length >= 4) {
+		unsigned int peak_bytes;
+
+		peak_bytes = (data[3] + 7) / 8;
+		if (4 + peak_bytes > length)
+			break;
+
+		if (data[0] == CHANNEL_MASTER_VOLUME) {
+			signed int voladj_fixed;
+			double voladj_float;
+
+			/*
+			 * "The volume adjustment is encoded as a fixed
+			 * point decibel value, 16 bit signed integer
+			 * representing (adjustment*512), giving +/- 64
+			 * dB with a precision of 0.001953125 dB."
+			 */
+
+			voladj_fixed  = (data[1] << 8) | (data[2] << 0);
+			voladj_fixed |= -(voladj_fixed & 0x8000);
+
+			voladj_float  = (double) voladj_fixed / 512;
+
+			replay_gain_info->tuples[REPLAY_GAIN_TRACK].gain = voladj_float;
+			replay_gain_info->tuples[REPLAY_GAIN_ALBUM].gain = voladj_float;
+
+			g_debug("parseRVA2: Relative Volume "
+				"%+.1f dB adjustment (%s)\n",
+				voladj_float, id);
+
+			return true;
+		}
+
+		data   += 4 + peak_bytes;
+		length -= 4 + peak_bytes;
+	}
+
+	return false;
+}