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/*
* Copyright (C) 2003-2015 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 "TagRva2.hxx"
#include "ReplayGainInfo.hxx"
#include <id3tag.h>
#include <stdint.h>
#include <string.h>
enum class Rva2Channel : uint8_t {
OTHER = 0x00,
MASTER_VOLUME = 0x01,
FRONT_RIGHT = 0x02,
FRONT_LEFT = 0x03,
BACK_RIGHT = 0x04,
BACK_LEFT = 0x05,
FRONT_CENTRE = 0x06,
BACK_CENTRE = 0x07,
SUBWOOFER = 0x08
};
struct Rva2Data {
Rva2Channel type;
uint8_t volume_adjustment[2];
uint8_t peak_bits;
};
static inline id3_length_t
rva2_peak_bytes(const Rva2Data &data)
{
return (data.peak_bits + 7) / 8;
}
static inline int
rva2_fixed_volume_adjustment(const Rva2Data &data)
{
signed int voladj_fixed;
voladj_fixed = (data.volume_adjustment[0] << 8) |
data.volume_adjustment[1];
voladj_fixed |= -(voladj_fixed & 0x8000);
return voladj_fixed;
}
static inline float
rva2_float_volume_adjustment(const Rva2Data &data)
{
/*
* "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."
*/
return (float)rva2_fixed_volume_adjustment(data) / (float)512;
}
static inline bool
rva2_apply_data(ReplayGainInfo &rgi,
const Rva2Data &data, const id3_latin1_t *id)
{
if (data.type != Rva2Channel::MASTER_VOLUME)
return false;
float volume_adjustment = rva2_float_volume_adjustment(data);
if (strcmp((const char *)id, "album") == 0) {
rgi.tuples[REPLAY_GAIN_ALBUM].gain = volume_adjustment;
} else if (strcmp((const char *)id, "track") == 0) {
rgi.tuples[REPLAY_GAIN_TRACK].gain = volume_adjustment;
} else {
rgi.tuples[REPLAY_GAIN_ALBUM].gain = volume_adjustment;
rgi.tuples[REPLAY_GAIN_TRACK].gain = volume_adjustment;
}
return true;
}
static bool
rva2_apply_frame(ReplayGainInfo &replay_gain_info,
const struct id3_frame *frame)
{
const id3_latin1_t *id = id3_field_getlatin1(id3_frame_field(frame, 0));
id3_length_t length;
const id3_byte_t *data =
id3_field_getbinarydata(id3_frame_field(frame, 1), &length);
if (id == nullptr || data == nullptr)
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) {
const Rva2Data &d = *(const Rva2Data *)data;
unsigned int peak_bytes = rva2_peak_bytes(d);
if (4 + peak_bytes > length)
break;
if (rva2_apply_data(replay_gain_info, d, id))
return true;
data += 4 + peak_bytes;
length -= 4 + peak_bytes;
}
return false;
}
bool
tag_rva2_parse(struct id3_tag *tag, ReplayGainInfo &replay_gain_info)
{
bool found = false;
/* Loop through all RVA2 frames as some programs (e.g. mp3gain) store
track and album gain in separate tags */
const struct id3_frame *frame;
for (unsigned i = 0;
(frame = id3_tag_findframe(tag, "RVA2", i)) != nullptr;
++i)
if (rva2_apply_frame(replay_gain_info, frame))
found = true;
return found;
}
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