Source file: /~heha/hs/puh.zip/gain_analysis.h

/*  ReplayGainAnalysis - analyzes input samples and give the recommended dB change
 *  Copyright (C) 2001 David Robinson and Glen Sawyer
 *
 *  concept and filter values by David Robinson (David@Robinson.org)
 *    -- blame him if you think the idea is flawed
 *  coding by Glen Sawyer (mp3gain@hotmail.com) 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/
 */

#pragma once

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

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


#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) */

    enum { GAIN_NOT_ENOUGH_SAMPLES = -24601, GAIN_ANALYSIS_ERROR = 0, GAIN_ANALYSIS_OK =
            1, INIT_GAIN_ANALYSIS_ERROR = 0, INIT_GAIN_ANALYSIS_OK = 1
    };

    enum { MAX_ORDER = (BUTTER_ORDER > YULE_ORDER ? BUTTER_ORDER : YULE_ORDER)
            , MAX_SAMPLES_PER_WINDOW = ((MAX_SAMP_FREQ * RMS_WINDOW_TIME_NUMERATOR) / RMS_WINDOW_TIME_DENOMINATOR + 1) /* max. Samples per Time slice */
    };

struct replaygain_data {
  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[STEPS_per_dB * MAX_dB];
  uint32_t B[STEPS_per_dB * MAX_dB];
  int     InitGainAnalysis(long samplefreq);
  int     AnalyzeSamples(const Float_t * left_samples,
	const Float_t * right_samples, size_t num_samples, int num_channels);
  Float_t GetTitleGain();
};
#ifndef replaygain_data_defined
#define replaygain_data_defined
    typedef struct replaygain_data replaygain_t;
#endif
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