rockbox/firmware/replaygain.c
Daniel Stenberg 2acc0ac542 Updated our source code header to explicitly mention that we are GPL v2 or
later. We still need to hunt down snippets used that are not. 1324 modified
files...
http://www.rockbox.org/mail/archive/rockbox-dev-archive-2008-06/0060.shtml


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17847 a1c6a512-1295-4272-9138-f99709370657
2008-06-28 18:10:04 +00:00

457 lines
9.7 KiB
C

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2005 Magnus Holmgren
*
* 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <ctype.h>
#include <inttypes.h>
#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <system.h>
#include "id3.h"
#include "debug.h"
#include "replaygain.h"
/* The fixed point math routines (with the exception of fp_atof) are based
* on oMathFP by Dan Carter (http://orbisstudios.com).
*/
/* 12 bits of precision gives fairly accurate result, but still allows a
* compact implementation. The math code supports up to 13...
*/
#define FP_BITS (12)
#define FP_MASK ((1 << FP_BITS) - 1)
#define FP_ONE (1 << FP_BITS)
#define FP_TWO (2 << FP_BITS)
#define FP_HALF (1 << (FP_BITS - 1))
#define FP_LN2 ( 45426 >> (16 - FP_BITS))
#define FP_LN2_INV ( 94548 >> (16 - FP_BITS))
#define FP_EXP_ZERO ( 10922 >> (16 - FP_BITS))
#define FP_EXP_ONE ( -182 >> (16 - FP_BITS))
#define FP_EXP_TWO ( 4 >> (16 - FP_BITS))
#define FP_INF (0x7fffffff)
#define FP_LN10 (150902 >> (16 - FP_BITS))
#define FP_MAX_DIGITS (4)
#define FP_MAX_DIGITS_INT (10000)
#define FP_FAST_MUL_DIV
#ifdef FP_FAST_MUL_DIV
/* These macros can easily overflow, but they are good enough for our uses,
* and saves some code.
*/
#define fp_mul(x, y) (((x) * (y)) >> FP_BITS)
#define fp_div(x, y) (((x) << FP_BITS) / (y))
#else
static long fp_mul(long x, long y)
{
long x_neg = 0;
long y_neg = 0;
long rc;
if ((x == 0) || (y == 0))
{
return 0;
}
if (x < 0)
{
x_neg = 1;
x = -x;
}
if (y < 0)
{
y_neg = 1;
y = -y;
}
rc = (((x >> FP_BITS) * (y >> FP_BITS)) << FP_BITS)
+ (((x & FP_MASK) * (y & FP_MASK)) >> FP_BITS)
+ ((x & FP_MASK) * (y >> FP_BITS))
+ ((x >> FP_BITS) * (y & FP_MASK));
if ((x_neg ^ y_neg) == 1)
{
rc = -rc;
}
return rc;
}
static long fp_div(long x, long y)
{
long x_neg = 0;
long y_neg = 0;
long shifty;
long rc;
int msb = 0;
int lsb = 0;
if (x == 0)
{
return 0;
}
if (y == 0)
{
return (x < 0) ? -FP_INF : FP_INF;
}
if (x < 0)
{
x_neg = 1;
x = -x;
}
if (y < 0)
{
y_neg = 1;
y = -y;
}
while ((x & (1 << (30 - msb))) == 0)
{
msb++;
}
while ((y & (1 << lsb)) == 0)
{
lsb++;
}
shifty = FP_BITS - (msb + lsb);
rc = ((x << msb) / (y >> lsb));
if (shifty > 0)
{
rc <<= shifty;
}
else
{
rc >>= -shifty;
}
if ((x_neg ^ y_neg) == 1)
{
rc = -rc;
}
return rc;
}
#endif /* FP_FAST_MUL_DIV */
static long fp_exp(long x)
{
long k;
long z;
long R;
long xp;
if (x == 0)
{
return FP_ONE;
}
k = (fp_mul(abs(x), FP_LN2_INV) + FP_HALF) & ~FP_MASK;
if (x < 0)
{
k = -k;
}
x -= fp_mul(k, FP_LN2);
z = fp_mul(x, x);
R = FP_TWO + fp_mul(z, FP_EXP_ZERO + fp_mul(z, FP_EXP_ONE
+ fp_mul(z, FP_EXP_TWO)));
xp = FP_ONE + fp_div(fp_mul(FP_TWO, x), R - x);
if (k < 0)
{
k = FP_ONE >> (-k >> FP_BITS);
}
else
{
k = FP_ONE << (k >> FP_BITS);
}
return fp_mul(k, xp);
}
static long fp_exp10(long x)
{
if (x == 0)
{
return FP_ONE;
}
return fp_exp(fp_mul(FP_LN10, x));
}
static long fp_atof(const char* s, int precision)
{
long int_part = 0;
long int_one = 1 << precision;
long frac_part = 0;
long frac_count = 0;
long frac_max = ((precision * 4) + 12) / 13;
long frac_max_int = 1;
long sign = 1;
bool point = false;
while ((*s != '\0') && isspace(*s))
{
s++;
}
if (*s == '-')
{
sign = -1;
s++;
}
else if (*s == '+')
{
s++;
}
while (*s != '\0')
{
if (*s == '.')
{
if (point)
{
break;
}
point = true;
}
else if (isdigit(*s))
{
if (point)
{
if (frac_count < frac_max)
{
frac_part = frac_part * 10 + (*s - '0');
frac_count++;
frac_max_int *= 10;
}
}
else
{
int_part = int_part * 10 + (*s - '0');
}
}
else
{
break;
}
s++;
}
while (frac_count < frac_max)
{
frac_part *= 10;
frac_count++;
frac_max_int *= 10;
}
return sign * ((int_part * int_one)
+ (((int64_t) frac_part * int_one) / frac_max_int));
}
static long convert_gain(long gain)
{
/* Don't allow unreasonably low or high gain changes.
* Our math code can't handle it properly anyway. :)
*/
if (gain < (-48 * FP_ONE))
{
gain = -48 * FP_ONE;
}
if (gain > (17 * FP_ONE))
{
gain = 17 * FP_ONE;
}
gain = fp_exp10(gain / 20) << (24 - FP_BITS);
return gain;
}
/* Get the sample scale factor in Q7.24 format from a gain value. Returns 0
* for no gain.
*
* str Gain in dB as a string. E.g., "-3.45 dB"; the "dB" part is ignored.
*/
static long get_replaygain(const char* str)
{
long gain = 0;
if (str)
{
gain = fp_atof(str, FP_BITS);
gain = convert_gain(gain);
}
return gain;
}
/* Get the peak volume in Q7.24 format.
*
* str Peak volume. Full scale is specified as "1.0". Returns 0 for no peak.
*/
static long get_replaypeak(const char* str)
{
long peak = 0;
if (str)
{
peak = fp_atof(str, 24);
}
return peak;
}
/* Get a sample scale factor in Q7.24 format from a gain value.
*
* int_gain Gain in dB, multiplied by 100.
*/
long get_replaygain_int(long int_gain)
{
return convert_gain(int_gain * FP_ONE / 100);
}
/* Parse a ReplayGain tag conforming to the "VorbisGain standard". If a
* valid tag is found, update mp3entry struct accordingly. Existing values
* are not overwritten. Returns number of bytes written to buffer.
*
* key Name of the tag.
* value Value of the tag.
* entry mp3entry struct to update.
* buffer Where to store the text for gain values (for later display).
* length Bytes left in buffer.
*/
long parse_replaygain(const char* key, const char* value,
struct mp3entry* entry, char* buffer, int length)
{
char **p = NULL;
if (((strcasecmp(key, "replaygain_track_gain") == 0)
|| (strcasecmp(key, "rg_radio") == 0)) && !entry->track_gain)
{
entry->track_gain = get_replaygain(value);
p = &(entry->track_gain_string);
}
else if (((strcasecmp(key, "replaygain_album_gain") == 0)
|| (strcasecmp(key, "rg_audiophile") == 0)) && !entry->album_gain)
{
entry->album_gain = get_replaygain(value);
p = &(entry->album_gain_string);
}
else if (((strcasecmp(key, "replaygain_track_peak") == 0)
|| (strcasecmp(key, "rg_peak") == 0)) && !entry->track_peak)
{
entry->track_peak = get_replaypeak(value);
}
else if ((strcasecmp(key, "replaygain_album_peak") == 0)
&& !entry->album_peak)
{
entry->album_peak = get_replaypeak(value);
}
if (p)
{
int len = strlen(value);
len = MIN(len, length - 1);
/* A few characters just isn't interesting... */
if (len > 1)
{
strncpy(buffer, value, len);
buffer[len] = 0;
*p = buffer;
return len + 1;
}
}
return 0;
}
/* Set ReplayGain values from integers. Existing values are not overwritten.
* Returns number of bytes written to buffer.
*
* album If true, set album values, otherwise set track values.
* gain Gain value in dB, multiplied by 512. 0 for no gain.
* peak Peak volume in Q7.24 format, where 1.0 is full scale. 0 for no
* peak volume.
* buffer Where to store the text for gain values (for later display).
* length Bytes left in buffer.
*/
long parse_replaygain_int(bool album, long gain, long peak,
struct mp3entry* entry, char* buffer, int length)
{
long len = 0;
if (buffer != NULL)
{
len = snprintf(buffer, length, "%d.%02d dB", gain / 512,
((abs(gain) & 0x01ff) * 100 + 256) / 512);
len++;
}
if (gain != 0)
{
gain = convert_gain(gain * FP_ONE / 512);
}
if (album)
{
entry->album_gain = gain;
entry->album_gain_string = buffer;
if (peak)
{
entry->album_peak = peak;
}
}
else
{
entry->track_gain = gain;
entry->track_gain_string = buffer;
if (peak)
{
entry->track_peak = peak;
}
}
return len;
}