gain_analysis.h

音频编码

/*
 *  ReplayGainAnalysis - analyzes input samples and give the recommended dB change
 *  Copyright (C) 2001 David Robinson and Glen Sawyer
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  concept and filter values by David Robinson ([e-mail])
 *    -- blame him if you think the idea is flawed
 *  coding by Glen Sawyer ([e-mail]) 735 W 255 N, Orem, UT 84057-4505 USA
 *    -- blame him if you think this runs too slowly, or the coding is otherwise flawed
 *
 *  For an explanation of the concepts and the basic algorithms involved, go to:
 *    http://www.replaygain.org/
 */

#ifndef GAIN_ANALYSIS_H
#define GAIN_ANALYSIS_H

#if HAVE_INTTYPES_H
# include <inttypes.h>
#else
# if HAVE_STDINT_H
#  include <stdint.h>
# endif
#endif

#ifdef __cplusplus
extern "C" {
#endif


typedef sample_t Float_t;         /* Type used for filtering */

#define GAIN_NOT_ENOUGH_SAMPLES  -24601
#define GAIN_ANALYSIS_ERROR           0
#define GAIN_ANALYSIS_OK              1

#define INIT_GAIN_ANALYSIS_ERROR      0
#define INIT_GAIN_ANALYSIS_OK         1

#define PINK_REF                64.82       /* 298640883795 */         /* calibration value for 89dB*/


#define YULE_ORDER         10
#define BUTTER_ORDER        2
#define YULE_FILTER     filterYule
#define BUTTER_FILTER   filterButter
#define RMS_PERCENTILE      0.95        /* percentile which is louder than the proposed level */
#define MAX_SAMP_FREQ   48000L          /* maximum allowed sample frequency [Hz] */
#define RMS_WINDOW_TIME_NUMERATOR    1L  
#define RMS_WINDOW_TIME_DENOMINATOR 20L /* numerator / denominator = time slice size [s] */
#define STEPS_per_dB      100.          /* Table entries per dB */
#define MAX_dB            120.          /* Table entries for 0...MAX_dB (normal max. values are 70...80 dB) */

#define MAX_ORDER               (BUTTER_ORDER > YULE_ORDER ? BUTTER_ORDER : YULE_ORDER)
#define MAX_SAMPLES_PER_WINDOW  (size_t) ((MAX_SAMP_FREQ * RMS_WINDOW_TIME_NUMERATOR) / RMS_WINDOW_TIME_DENOMINATOR + 1)      /* max. Samples per Time slice */




typedef struct
{
    Float_t          linprebuf [MAX_ORDER * 2];
    Float_t*         linpre;                                          /* left input samples, with pre-buffer */
    Float_t          lstepbuf  [MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
    Float_t*         lstep;                                           /* left "first step" (i.e. post first filter) samples */
    Float_t          loutbuf   [MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
    Float_t*         lout;                                            /* left "out" (i.e. post second filter) samples */
    Float_t          rinprebuf [MAX_ORDER * 2];
    Float_t*         rinpre;                                          /* right input samples ... */
    Float_t          rstepbuf  [MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
    Float_t*         rstep;
    Float_t          routbuf   [MAX_SAMPLES_PER_WINDOW + MAX_ORDER];
    Float_t*         rout;
    long             sampleWindow;                                    /* number of samples required to reach number of milliseconds required for RMS window */
    long             totsamp;
    double           lsum;
    double           rsum;
    int              freqindex;
    int              first;
    uint32_t  A [(size_t)(STEPS_per_dB * MAX_dB)];
    uint32_t  B [(size_t)(STEPS_per_dB * MAX_dB)];

} replaygain_t;






int     InitGainAnalysis (replaygain_t* rgData, long samplefreq );
int     AnalyzeSamples   (replaygain_t* rgData, const Float_t* left_samples, const Float_t* right_samples, size_t num_samples, int num_channels );
int		ResetSampleFrequency (replaygain_t* rgData, long samplefreq );
Float_t   GetTitleGain     (replaygain_t* rgData);
Float_t   GetAlbumGain     (replaygain_t* rgData);


#ifdef __cplusplus
}
#endif

#endif /* GAIN_ANALYSIS_H */