2 * ReplayGainAnalysis - analyzes input samples and give the recommended dB change
3 * Copyright (C) 2001 David Robinson and Glen Sawyer
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 * concept and filter values by David Robinson (David@Robinson.org)
20 * -- blame him if you think the idea is flawed
21 * coding by Glen Sawyer (mp3gain@hotmail.com) 735 W 255 N, Orem, UT 84057-4505 USA
22 * -- blame him if you think this runs too slowly, or the coding is otherwise flawed
24 * For an explanation of the concepts and the basic algorithms involved, go to:
25 * http://www.replaygain.org/
28 #ifndef GAIN_ANALYSIS_H
29 #define GAIN_ANALYSIS_H
31 #ifdef HAVE_INTTYPES_H
32 # include <inttypes.h>
44 typedef sample_t Float_t; /* Type used for filtering */
47 #define PINK_REF 64.82 /* 298640883795 */ /* calibration value for 89dB */
51 #define BUTTER_ORDER 2
52 #define YULE_FILTER filterYule
53 #define BUTTER_FILTER filterButter
54 #define RMS_PERCENTILE 0.95 /* percentile which is louder than the proposed level */
55 #define MAX_SAMP_FREQ 48000L /* maximum allowed sample frequency [Hz] */
56 #define RMS_WINDOW_TIME_NUMERATOR 1L
57 #define RMS_WINDOW_TIME_DENOMINATOR 20L /* numerator / denominator = time slice size [s] */
58 #define STEPS_per_dB 100 /* Table entries per dB */
59 #define MAX_dB 120 /* Table entries for 0...MAX_dB (normal max. values are 70...80 dB) */
61 enum { GAIN_NOT_ENOUGH_SAMPLES = -24601, GAIN_ANALYSIS_ERROR = 0, GAIN_ANALYSIS_OK =
62 1, INIT_GAIN_ANALYSIS_ERROR = 0, INIT_GAIN_ANALYSIS_OK = 1
65 enum { MAX_ORDER = (BUTTER_ORDER > YULE_ORDER ? BUTTER_ORDER : YULE_ORDER)
66 , MAX_SAMPLES_PER_WINDOW = ((MAX_SAMP_FREQ * RMS_WINDOW_TIME_NUMERATOR) / RMS_WINDOW_TIME_DENOMINATOR + 1) /* max. Samples per Time slice */
69 struct replaygain_data {
70 Float_t linprebuf[MAX_ORDER * 2];
71 Float_t *linpre; /* left input samples, with pre-buffer */
72 Float_t lstepbuf[MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
73 Float_t *lstep; /* left "first step" (i.e. post first filter) samples */
74 Float_t loutbuf[MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
75 Float_t *lout; /* left "out" (i.e. post second filter) samples */
76 Float_t rinprebuf[MAX_ORDER * 2];
77 Float_t *rinpre; /* right input samples ... */
78 Float_t rstepbuf[MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
80 Float_t routbuf[MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
82 long sampleWindow; /* number of samples required to reach number of milliseconds required for RMS window */
88 uint32_t A[STEPS_per_dB * MAX_dB];
89 uint32_t B[STEPS_per_dB * MAX_dB];
92 #ifndef replaygain_data_defined
93 #define replaygain_data_defined
94 typedef struct replaygain_data replaygain_t;
100 int InitGainAnalysis(replaygain_t * rgData, long samplefreq);
101 int AnalyzeSamples(replaygain_t * rgData, const Float_t * left_samples,
102 const Float_t * right_samples, size_t num_samples, int num_channels);
103 Float_t GetTitleGain(replaygain_t * rgData);
109 #endif /* GAIN_ANALYSIS_H */