gain_analysis.c

音频编码

/*
 *  ReplayGainAnalysis - analyzes input samples and give the recommended dB change
 *  Copyright (C) 2001 David Robinson and Glen Sawyer
 *  Improvements and optimizations added by Frank Klemm, and by Marcel Muller 
 *
 *  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
 *  original coding by Glen Sawyer ([e-mail])
 *    -- blame him if you think this runs too slowly, or the coding is otherwise flawed
 *
 *  lots of code improvements by Frank Klemm ( http://www.uni-jena.de/~pfk/mpp/ )
 *    -- credit him for all the _good_ programming ;)
 *
 *
 *  For an explanation of the concepts and the basic algorithms involved, go to:
 *    http://www.replaygain.org/
 */

/*
 *  Here's the deal. Call
 *
 *    InitGainAnalysis ( long samplefreq );
 *
 *  to initialize everything. Call
 *
 *    AnalyzeSamples ( const Float_t*  left_samples,
 *                     const Float_t*  right_samples,
 *                     size_t          num_samples,
 *                     int             num_channels );
 *
 *  as many times as you want, with as many or as few samples as you want.
 *  If mono, pass the sample buffer in through left_samples, leave
 *  right_samples NULL, and make sure num_channels = 1.
 *
 *    GetTitleGain()
 *
 *  will return the recommended dB level change for all samples analyzed
 *  SINCE THE LAST TIME you called GetTitleGain() OR InitGainAnalysis().
 *
 *    GetAlbumGain()
 *
 *  will return the recommended dB level change for all samples analyzed
 *  since InitGainAnalysis() was called and finalized with GetTitleGain().
 *
 *  Pseudo-code to process an album:
 *
 *    Float_t       l_samples [4096];
 *    Float_t       r_samples [4096];
 *    size_t        num_samples;
 *    unsigned int  num_songs;
 *    unsigned int  i;
 *
 *    InitGainAnalysis ( 44100 );
 *    for ( i = 1; i <= num_songs; i++ ) {
 *        while ( ( num_samples = getSongSamples ( song[i], left_samples, right_samples ) ) > 0 )
 *            AnalyzeSamples ( left_samples, right_samples, num_samples, 2 );
 *        fprintf ("Recommended dB change for song %2d: %+6.2f dB\n", i, GetTitleGain() );
 *    }
 *    fprintf ("Recommended dB change for whole album: %+6.2f dB\n", GetAlbumGain() );
 */

/*
 *  So here's the main source of potential code confusion:
 *
 *  The filters applied to the incoming samples are IIR filters,
 *  meaning they rely on up to <filter order> number of previous samples
 *  AND up to <filter order> number of previous filtered samples.
 *
 *  I set up the AnalyzeSamples routine to minimize memory usage and interface
 *  complexity. The speed isn't compromised too much (I don't think), but the
 *  internal complexity is higher than it should be for such a relatively
 *  simple routine.
 *
 *  Optimization/clarity suggestions are welcome.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "machine.h"
#include "gain_analysis.h"

/* for each filter: */
/* [0] 48 kHz, [1] 44.1 kHz, [2] 32 kHz, [3] 24 kHz, [4] 22050 Hz, [5] 16 kHz, [6] 12 kHz, [7] is 11025 Hz, [8] 8 kHz */

#ifdef WIN32
#pragma warning ( disable : 4305 )
#endif

static const Float_t ABYule[9][2*YULE_ORDER + 1] = {
    {0.03857599435200, -3.84664617118067, -0.02160367184185,  7.81501653005538, -0.00123395316851,-11.34170355132042, -0.00009291677959, 13.05504219327545, -0.01655260341619,-12.28759895145294,  0.02161526843274,  9.48293806319790, -0.02074045215285, -5.87257861775999,  0.00594298065125,  2.75465861874613,  0.00306428023191, -0.86984376593551,  0.00012025322027,  0.13919314567432,  0.00288463683916 },
    {0.05418656406430, -3.47845948550071, -0.02911007808948,  6.36317777566148, -0.00848709379851, -8.54751527471874, -0.00851165645469,  9.47693607801280, -0.00834990904936, -8.81498681370155,  0.02245293253339,  6.85401540936998, -0.02596338512915, -4.39470996079559,  0.01624864962975,  2.19611684890774, -0.00240879051584, -0.75104302451432,  0.00674613682247,  0.13149317958808, -0.00187763777362 },
    {0.15457299681924, -2.37898834973084, -0.09331049056315,  2.84868151156327, -0.06247880153653, -2.64577170229825,  0.02163541888798,  2.23697657451713, -0.05588393329856, -1.67148153367602,  0.04781476674921,  1.00595954808547,  0.00222312597743, -0.45953458054983,  0.03174092540049,  0.16378164858596, -0.01390589421898, -0.05032077717131,  0.00651420667831,  0.02347897407020, -0.00881362733839 },
    {0.30296907319327, -1.61273165137247, -0.22613988682123,  1.07977492259970, -0.08587323730772, -0.25656257754070,  0.03282930172664, -0.16276719120440, -0.00915702933434, -0.22638893773906, -0.02364141202522,  0.39120800788284, -0.00584456039913, -0.22138138954925,  0.06276101321749,  0.04500235387352, -0.00000828086748,  0.02005851806501,  0.00205861885564,  0.00302439095741, -0.02950134983287 },
    {0.33642304856132, -1.49858979367799, -0.25572241425570,  0.87350271418188, -0.11828570177555,  0.12205022308084,  0.11921148675203, -0.80774944671438, -0.07834489609479,  0.47854794562326, -0.00469977914380, -0.12453458140019, -0.00589500224440, -0.04067510197014,  0.05724228140351,  0.08333755284107,  0.00832043980773, -0.04237348025746, -0.01635381384540,  0.02977207319925, -0.01760176568150 },
    {0.44915256608450, -0.62820619233671, -0.14351757464547,  0.29661783706366, -0.22784394429749, -0.37256372942400, -0.01419140100551,  0.00213767857124,  0.04078262797139, -0.42029820170918, -0.12398163381748,  0.22199650564824,  0.04097565135648,  0.00613424350682,  0.10478503600251,  0.06747620744683, -0.01863887810927,  0.05784820375801, -0.03193428438915,  0.03222754072173,  0.00541907748707 },
    {0.56619470757641, -1.04800335126349, -0.75464456939302,  0.29156311971249,  0.16242137742230, -0.26806001042947,  0.16744243493672,  0.00819999645858, -0.18901604199609,  0.45054734505008,  0.30931782841830, -0.33032403314006, -0.27562961986224,  0.06739368333110,  0.00647310677246, -0.04784254229033,  0.08647503780351,  0.01639907836189, -0.03788984554840,  0.01807364323573, -0.00588215443421 },
    {0.58100494960553, -0.51035327095184, -0.53174909058578, -0.31863563325245, -0.14289799034253, -0.20256413484477,  0.17520704835522,  0.14728154134330,  0.02377945217615,  0.38952639978999,  0.15558449135573, -0.23313271880868, -0.25344790059353, -0.05246019024463,  0.01628462406333, -0.02505961724053,  0.06920467763959,  0.02442357316099, -0.03721611395801,  0.01818801111503, -0.00749618797172 },
    {0.53648789255105, -0.25049871956020, -0.42163034350696, -0.43193942311114, -0.00275953611929, -0.03424681017675,  0.04267842219415, -0.04678328784242, -0.10214864179676,  0.26408300200955,  0.14590772289388,  0.15113130533216, -0.02459864859345, -0.17556493366449, -0.11202315195388, -0.18823009262115, -0.04060034127000,  0.05477720428674,  0.04788665548180,  0.04704409688120, -0.02217936801134 }
};

static const Float_t ABButter[9][2*BUTTER_ORDER + 1] = {
    {0.98621192462708, -1.97223372919527, -1.97242384925416,  0.97261396931306,  0.98621192462708 },
    {0.98500175787242, -1.96977855582618, -1.97000351574484,  0.97022847566350,  0.98500175787242 },
    {0.97938932735214, -1.95835380975398, -1.95877865470428,  0.95920349965459,  0.97938932735214 },
    {0.97531843204928, -1.95002759149878, -1.95063686409857,  0.95124613669835,  0.97531843204928 },
    {0.97316523498161, -1.94561023566527, -1.94633046996323,  0.94705070426118,  0.97316523498161 },
    {0.96454515552826, -1.92783286977036, -1.92909031105652,  0.93034775234268,  0.96454515552826 },
    {0.96009142950541, -1.91858953033784, -1.92018285901082,  0.92177618768381,  0.96009142950541 },
    {0.95856916599601, -1.91542108074780, -1.91713833199203,  0.91885558323625,  0.95856916599601 },
    {0.94597685600279, -1.88903307939452, -1.89195371200558,  0.89487434461664,  0.94597685600279 }
};


#ifdef WIN32
#pragma warning ( default : 4305 )
#endif

/* When calling this procedure, make sure that ip[-order] and op[-order] point to real data! */

static void
filterYule (const Float_t* input, Float_t* output, size_t nSamples, const Float_t* kernel)
{
    /*register double  y;*/

    while (nSamples--) {
        *output =  1e-10  /* 1e-10 is a hack to avoid slowdown because of denormals */
         +  input [0]  * kernel[0]
         - output[-1] * kernel[1]
         + input [-1] * kernel[2]
         - output[-2] * kernel[3]
         + input [-2] * kernel[4]
         - output[-3] * kernel[5]
         + input [-3] * kernel[6]
         - output[-4] * kernel[7]
         + input [-4] * kernel[8]
         - output[-5] * kernel[9]
         + input [-5] * kernel[10]
         - output[-6] * kernel[11]
         + input [-6] * kernel[12]
         - output[-7] * kernel[13]
         + input [-7] * kernel[14]
         - output[-8] * kernel[15]
         + input [-8] * kernel[16]
         - output[-9] * kernel[17]
         + input [-9] * kernel[18]
         - output[-10]* kernel[19]
         + input [-10]* kernel[20];
        ++output;
        ++input;
        /* *output++ = (Float_t)y; */
    }
}

static void
filterButter (const Float_t* input, Float_t* output, size_t nSamples, const Float_t* kernel)
{   /*register double  y;*/

    while (nSamples--) {
        *output =  input [0]  * kernel[0]
         - output[-1] * kernel[1]
         + input [-1] * kernel[2]
         - output[-2] * kernel[3]
         + input [-2] * kernel[4];
        ++output;
        ++input;
        /* *output++ = (Float_t)y; */
    }
}


/* returns a INIT_GAIN_ANALYSIS_OK if successful, INIT_GAIN_ANALYSIS_ERROR if not */

int
ResetSampleFrequency (replaygain_t* rgData, long samplefreq ) {
    int  i;

    /* zero out initial values */
    for ( i = 0; i < MAX_ORDER; i++ )
        rgData->linprebuf[i] = rgData->lstepbuf[i]
                            = rgData->loutbuf[i]
                            = rgData->rinprebuf[i]
                            = rgData->rstepbuf[i]
                            = rgData->routbuf[i] = 0.;

    switch ( (int)(samplefreq) ) {
        case 48000: rgData->freqindex = 0; break;
        case 44100: rgData->freqindex = 1; break;
        case 32000: rgData->freqindex = 2; break;
        case 24000: rgData->freqindex = 3; break;
        case 22050: rgData->freqindex = 4; break;
        case 16000: rgData->freqindex = 5; break;
        case 12000: rgData->freqindex = 6; break;
        case 11025: rgData->freqindex = 7; break;