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/*
* 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;
}
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