diff options
Diffstat (limited to 'apps')
| -rw-r--r-- | apps/metadata/mpc.c | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/apps/metadata/mpc.c b/apps/metadata/mpc.c index a8cd128828..c6f3c3df72 100644 --- a/apps/metadata/mpc.c +++ b/apps/metadata/mpc.c @@ -8,6 +8,7 @@ * $Id$ * * Copyright (C) 2005 Thom Johansen + * Copyright (C) 2010 Andree Buschmann * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -27,9 +28,11 @@ #include "metadata_parsers.h" #include "logf.h" #include "replaygain.h" +#include "fixedpoint.h" -/* Needed for replay gain in sv8, please search MPC_OLD_GAIN_REF in libmusepack */ -#define SV8_TO_SV7_CONVERT_GAIN (6482) /* 64.82 * 100 */ +/* Needed for replay gain and clipping prevention of SV8 files. */ +#define SV8_TO_SV7_CONVERT_GAIN (6482) /* 64.82 * 100, MPC_OLD_GAIN_REF */ +#define SV8_TO_SV7_CONVERT_PEAK (23119) /* 256 * 20 * log10(32768) */ static int set_replaygain_sv7(struct mp3entry* id3, bool album, @@ -39,15 +42,9 @@ static int set_replaygain_sv7(struct mp3entry* id3, long gain = (int16_t) ((value >> 16) & 0xffff); long peak = (uint16_t) (value & 0xffff); - /* Remark: mpc sv7 outputs peak as amplitude, not as dB. The following - * useage of peak is not correct and needs to be fixed. */ - /* We use a peak value of 0 to indicate a given gain type isn't used. */ if (peak != 0) { - /* Use the Xing TOC field to store ReplayGain strings for use in the - * ID3 screen, since Musepack files shouldn't need to use it in any - * other way. - */ + /* Save the ReplayGain data to id3-structure for further processing. */ used += parse_replaygain_int(album, gain * 512 / 100, peak << 9, id3, id3->toc + used, sizeof(id3->toc) - used); } @@ -63,13 +60,19 @@ static int set_replaygain_sv8(struct mp3entry* id3, { gain = (long)(SV8_TO_SV7_CONVERT_GAIN - ((gain*100)/256)); + /* Transform SV8's logarithmic peak representation to the desired linear + * representation: linear = pow(10, peak/256/20). + * + * FP_BITS = 24 bits = desired fp representation for dsp routines + * FRAC_BITS = 12 bits = resolution used for fp_bits + * fp_factor(peak*(1<<FRAC_BITS)/256, FRAC_BITS) << (FP_BITS-FRAC_BITS) + **/ + peak = (fp_factor((peak-SV8_TO_SV7_CONVERT_PEAK)*16, 12) << 12); + /* We use a peak value of 0 to indicate a given gain type isn't used. */ if (peak != 0) { - /* Use the Xing TOC field to store ReplayGain strings for use in the - * ID3 screen, since Musepack files shouldn't need to use it in any - * other way. - */ - used += parse_replaygain_int(album, gain * 512 / 100, peak << 9, + /* Save the ReplayGain data to id3-structure for further processing. */ + used += parse_replaygain_int(album, gain * 512 / 100, peak, id3, id3->toc + used, sizeof(id3->toc) - used); } |