111 lines
2.9 KiB
C
111 lines
2.9 KiB
C
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/*
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* Copyright (C) 2003-2010 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include "tag_rva2.h"
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#include "replay_gain_info.h"
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#include <glib.h>
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#include <id3tag.h>
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bool
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tag_rva2_parse(struct id3_tag *tag, struct replay_gain_info *replay_gain_info)
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{
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struct id3_frame const * frame;
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id3_latin1_t const *id;
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id3_byte_t const *data;
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id3_length_t length;
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enum {
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CHANNEL_OTHER = 0x00,
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CHANNEL_MASTER_VOLUME = 0x01,
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CHANNEL_FRONT_RIGHT = 0x02,
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CHANNEL_FRONT_LEFT = 0x03,
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CHANNEL_BACK_RIGHT = 0x04,
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CHANNEL_BACK_LEFT = 0x05,
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CHANNEL_FRONT_CENTRE = 0x06,
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CHANNEL_BACK_CENTRE = 0x07,
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CHANNEL_SUBWOOFER = 0x08
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};
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/* relative volume adjustment information */
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frame = id3_tag_findframe(tag, "RVA2", 0);
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if (frame == NULL)
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return false;
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id = id3_field_getlatin1(id3_frame_field(frame, 0));
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data = id3_field_getbinarydata(id3_frame_field(frame, 1),
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&length);
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if (id == NULL || data == NULL)
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return false;
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/*
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* "The 'identification' string is used to identify the
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* situation and/or device where this adjustment should apply.
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* The following is then repeated for every channel
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*
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* Type of channel $xx
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* Volume adjustment $xx xx
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* Bits representing peak $xx
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* Peak volume $xx (xx ...)"
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*/
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while (length >= 4) {
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unsigned int peak_bytes;
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peak_bytes = (data[3] + 7) / 8;
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if (4 + peak_bytes > length)
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break;
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if (data[0] == CHANNEL_MASTER_VOLUME) {
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signed int voladj_fixed;
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double voladj_float;
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/*
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* "The volume adjustment is encoded as a fixed
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* point decibel value, 16 bit signed integer
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* representing (adjustment*512), giving +/- 64
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* dB with a precision of 0.001953125 dB."
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*/
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voladj_fixed = (data[1] << 8) | (data[2] << 0);
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voladj_fixed |= -(voladj_fixed & 0x8000);
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voladj_float = (double) voladj_fixed / 512;
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replay_gain_info->tuples[REPLAY_GAIN_TRACK].gain = voladj_float;
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replay_gain_info->tuples[REPLAY_GAIN_ALBUM].gain = voladj_float;
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g_debug("parseRVA2: Relative Volume "
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"%+.1f dB adjustment (%s)\n",
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voladj_float, id);
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return true;
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}
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data += 4 + peak_bytes;
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length -= 4 + peak_bytes;
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}
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return false;
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}
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