diff options
Diffstat (limited to 'src/tag_rva2.c')
-rw-r--r-- | src/tag_rva2.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/tag_rva2.c b/src/tag_rva2.c new file mode 100644 index 000000000..35f12118f --- /dev/null +++ b/src/tag_rva2.c @@ -0,0 +1,136 @@ +/* + * 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 <stdint.h> +#include <glib.h> +#include <id3tag.h> + +enum rva2_channel { + 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 +}; + +struct rva2_data { + uint8_t type; + uint8_t volume_adjustment[2]; + uint8_t peak_bits; +}; + +static inline id3_length_t +rva2_peak_bytes(const struct rva2_data *data) +{ + return (data->peak_bits + 7) / 8; +} + +static inline int +rva2_fixed_volume_adjustment(const struct rva2_data *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 struct rva2_data *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(struct replay_gain_info *replay_gain_info, + const struct rva2_data *data) +{ + if (data->type != CHANNEL_MASTER_VOLUME) + return false; + + float volume_adjustment = rva2_float_volume_adjustment(data); + + replay_gain_info->tuples[REPLAY_GAIN_TRACK].gain = volume_adjustment; + replay_gain_info->tuples[REPLAY_GAIN_ALBUM].gain = volume_adjustment; + + return true; +} + +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; + + /* 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) { + const struct rva2_data *d = (const struct rva2_data *)data; + unsigned int peak_bytes = rva2_peak_bytes(d); + if (4 + peak_bytes > length) + break; + + if (rva2_apply_data(replay_gain_info, d)) + return true; + + data += 4 + peak_bytes; + length -= 4 + peak_bytes; + } + + return false; +} |