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  1. /*
  2.  * Copyright (c) 1998 - 2009 Conifer Software
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. /**
  22.  * @file
  23.  * ReplayGain scanner
  24.  */
  25.  
  26. #include "libavutil/avassert.h"
  27. #include "libavutil/channel_layout.h"
  28. #include "audio.h"
  29. #include "avfilter.h"
  30. #include "internal.h"
  31.  
  32. #define HISTOGRAM_SLOTS 12000
  33. #define BUTTER_ORDER        2
  34. #define YULE_ORDER         10
  35.  
  36. typedef struct ReplayGainFreqInfo {
  37.     int    sample_rate;
  38.     double BYule[YULE_ORDER + 1];
  39.     double AYule[YULE_ORDER + 1];
  40.     double BButter[BUTTER_ORDER + 1];
  41.     double AButter[BUTTER_ORDER + 1];
  42. } ReplayGainFreqInfo;
  43.  
  44. static const ReplayGainFreqInfo freqinfos[] =
  45. {
  46.     {
  47.         192000,
  48.         {  0.01184742123123, -0.04631092400086,  0.06584226961238,
  49.           -0.02165588522478, -0.05656260778952,  0.08607493592760,
  50.           -0.03375544339786, -0.04216579932754,  0.06416711490648,
  51.           -0.03444708260844,  0.00697275872241 },
  52.         {  1.00000000000000, -5.24727318348167, 10.60821585192244,
  53.           -8.74127665810413, -1.33906071371683,  8.07972882096606,
  54.           -5.46179918950847,  0.54318070652536,  0.87450969224280,
  55.           -0.34656083539754,  0.03034796843589 },
  56.         {  0.99653501465135, -1.99307002930271,  0.99653501465135 },
  57.         {  1.00000000000000, -1.99305802314321,  0.99308203546221 },
  58.     },
  59.     {
  60.         176400,
  61.         {  0.00268568524529, -0.00852379426080,  0.00852704191347,
  62.            0.00146116310295, -0.00950855828762,  0.00625449515499,
  63.            0.00116183868722, -0.00362461417136,  0.00203961000134,
  64.           -0.00050664587933,  0.00004327455427 },
  65.         {  1.00000000000000, -5.57512782763045, 12.44291056065794,
  66.          -12.87462799681221,  3.08554846961576,  6.62493459880692,
  67.           -7.07662766313248,  2.51175542736441,  0.06731510802735,
  68.           -0.24567753819213,  0.03961404162376 },
  69.         {  0.99622916581118, -1.99245833162236,  0.99622916581118 },
  70.         {  1.00000000000000, -1.99244411238133,  0.99247255086339 },
  71.     },
  72.     {
  73.         144000,
  74.         {  0.00639682359450, -0.02556437970955,  0.04230854400938,
  75.           -0.03722462201267,  0.01718514827295,  0.00610592243009,
  76.           -0.03065965747365,  0.04345745003539, -0.03298592681309,
  77.            0.01320937236809, -0.00220304127757 },
  78.         {  1.00000000000000, -6.14814623523425, 15.80002457141566,
  79.          -20.78487587686937, 11.98848552310315,  3.36462015062606,
  80.          -10.22419868359470,  6.65599702146473, -1.67141861110485,
  81.           -0.05417956536718,  0.07374767867406 },
  82.         {  0.99538268958706, -1.99076537917413,  0.99538268958706 },
  83.         {  1.00000000000000, -1.99074405950505,  0.99078669884321 },
  84.     },
  85.     {
  86.         128000,
  87.         {  0.00553120584305, -0.02112620545016,  0.03549076243117,
  88.           -0.03362498312306,  0.01425867248183,  0.01344686928787,
  89.           -0.03392770787836,  0.03464136459530, -0.02039116051549,
  90.            0.00667420794705, -0.00093763762995 },
  91.         {  1.00000000000000, -6.14581710839925, 16.04785903675838,
  92.          -22.19089131407749, 15.24756471580286, -0.52001440400238,
  93.           -8.00488641699940,  6.60916094768855, -2.37856022810923,
  94.            0.33106947986101,  0.00459820832036 },
  95.         {  0.99480702681278, -1.98961405362557,  0.99480702681278 },
  96.         {  1.00000000000000, -1.98958708647324,  0.98964102077790 },
  97.     },
  98.     {
  99.         112000,
  100.         {  0.00528778718259, -0.01893240907245,  0.03185982561867,
  101.           -0.02926260297838,  0.00715743034072,  0.01985743355827,
  102.           -0.03222614850941,  0.02565681978192, -0.01210662313473,
  103.            0.00325436284541, -0.00044173593001 },
  104.         {  1.00000000000000, -6.24932108456288, 17.42344320538476,
  105.          -27.86819709054896, 26.79087344681326,-13.43711081485123,
  106.           -0.66023612948173,  6.03658091814935, -4.24926577030310,
  107.            1.40829268709186, -0.19480852628112 },
  108.         {  0.99406737810867, -1.98813475621734,  0.99406737810867 },
  109.         {  1.00000000000000, -1.98809955990514,  0.98816995252954 },
  110.     },
  111.     {
  112.         96000,
  113.         {  0.00588138296683, -0.01613559730421,  0.02184798954216,
  114.           -0.01742490405317,  0.00464635643780,  0.01117772513205,
  115.           -0.02123865824368,  0.01959354413350, -0.01079720643523,
  116.            0.00352183686289, -0.00063124341421 },
  117.         {  1.00000000000000, -5.97808823642008, 16.21362507964068,
  118.          -25.72923730652599, 25.40470663139513,-14.66166287771134,
  119.            2.81597484359752,  2.51447125969733, -2.23575306985286,
  120.            0.75788151036791, -0.10078025199029 },
  121.         {  0.99308203517541, -1.98616407035082,  0.99308203517541 },
  122.         {  1.00000000000000, -1.98611621154089,  0.98621192916075 },
  123.     },
  124.     {
  125.         88200,
  126.         {  0.02667482047416, -0.11377479336097,  0.23063167910965,
  127.           -0.30726477945593,  0.33188520686529, -0.33862680249063,
  128.            0.31807161531340, -0.23730796929880,  0.12273894790371,
  129.           -0.03840017967282,  0.00549673387936 },
  130.         {  1.00000000000000, -6.31836451657302, 18.31351310801799,
  131.          -31.88210014815921, 36.53792146976740,-28.23393036467559,
  132.           14.24725258227189, -4.04670980012854,  0.18865757280515,
  133.            0.25420333563908, -0.06012333531065 },
  134.         {  0.99247255046129, -1.98494510092259,  0.99247255046129 },
  135.         {  1.00000000000000, -1.98488843762335,  0.98500176422183 },
  136.     },
  137.     {
  138.         64000,
  139.         {  0.02613056568174, -0.08128786488109,  0.14937282347325,
  140.           -0.21695711675126,  0.25010286673402, -0.23162283619278,
  141.            0.17424041833052, -0.10299599216680,  0.04258696481981,
  142.           -0.00977952936493,  0.00105325558889 },
  143.         {  1.00000000000000, -5.73625477092119, 16.15249794355035,
  144.          -29.68654912464508, 39.55706155674083,-39.82524556246253,
  145.           30.50605345013009,-17.43051772821245,  7.05154573908017,
  146.           -1.80783839720514,  0.22127840210813 },
  147.         {  0.98964101933472, -1.97928203866944,  0.98964101933472 },
  148.         {  1.00000000000000, -1.97917472731009,  0.97938935002880 },
  149.     },
  150.     {
  151.         56000,
  152.         {  0.03144914734085, -0.06151729206963,  0.08066788708145,
  153.           -0.09737939921516,  0.08943210803999, -0.06989984672010,
  154.            0.04926972841044, -0.03161257848451,  0.01456837493506,
  155.           -0.00316015108496,  0.00132807215875 },
  156.         {  1.00000000000000, -4.87377313090032, 12.03922160140209,
  157.          -20.10151118381395, 25.10388534415171,-24.29065560815903,
  158.           18.27158469090663,-10.45249552560593,  4.30319491872003,
  159.           -1.13716992070185,  0.14510733527035 },
  160.         {  0.98816995007392, -1.97633990014784,  0.98816995007392 },
  161.         {  1.00000000000000, -1.97619994516973,  0.97647985512594 },
  162.     },
  163.     {
  164.         48000,
  165.         {  0.03857599435200, -0.02160367184185, -0.00123395316851,
  166.           -0.00009291677959, -0.01655260341619,  0.02161526843274,
  167.           -0.02074045215285,  0.00594298065125,  0.00306428023191,
  168.            0.00012025322027,  0.00288463683916 },
  169.         {  1.00000000000000, -3.84664617118067,  7.81501653005538,
  170.          -11.34170355132042, 13.05504219327545,-12.28759895145294,
  171.            9.48293806319790, -5.87257861775999,  2.75465861874613,
  172.           -0.86984376593551,  0.13919314567432 },
  173.         {  0.98621192462708, -1.97242384925416,  0.98621192462708 },
  174.         {  1.00000000000000, -1.97223372919527,  0.97261396931306 },
  175.     },
  176.     {
  177.         44100,
  178.         {  0.05418656406430, -0.02911007808948, -0.00848709379851,
  179.           -0.00851165645469, -0.00834990904936,  0.02245293253339,
  180.           -0.02596338512915,  0.01624864962975, -0.00240879051584,
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  183.           -8.54751527471874,  9.47693607801280, -8.81498681370155,
  184.            6.85401540936998, -4.39470996079559,  2.19611684890774,
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  186.         {  0.98500175787242, -1.97000351574484,  0.98500175787242 },
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  189.     {
  190.         37800,
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  193.           -0.01603261863207,  0.01936763028546,  0.00760044736442,
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  200.         {  1.00000000000000, -1.96474258269041,  0.96535344991740 },
  201.     },
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  203.         32000,
  204.         {  0.15457299681924, -0.09331049056315, -0.06247880153653,
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  207.            0.00651420667831, -0.00881362733839 },
  208.         {  1.00000000000000, -2.37898834973084,  2.84868151156327,
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  210.            1.00595954808547, -0.45953458054983,  0.16378164858596,
  211.           -0.05032077717131,  0.02347897407020 },
  212.         {  0.97938932735214, -1.95877865470428,  0.97938932735214 },
  213.         {  1.00000000000000, -1.95835380975398,  0.95920349965459 },
  214.     },
  215.     {
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  217.         {  0.30296907319327, -0.22613988682123, -0.08587323730772,
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  219.           -0.00584456039913,  0.06276101321749, -0.00000828086748,
  220.            0.00205861885564, -0.02950134983287 },
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  223.            0.39120800788284, -0.22138138954925,  0.04500235387352,
  224.            0.02005851806501,  0.00302439095741 },
  225.         {  0.97531843204928, -1.95063686409857,  0.97531843204928 },
  226.         {  1.00000000000000, -1.95002759149878,  0.95124613669835 },
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  233.           -0.01635381384540, -0.01760176568150 },
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  281.         11025,
  282.         {  0.58100494960553, -0.53174909058578, -0.14289799034253,
  283.            0.17520704835522,  0.02377945217615,  0.15558449135573,
  284.           -0.25344790059353,  0.01628462406333,  0.06920467763959,
  285.           -0.03721611395801, -0.00749618797172 },
  286.         {  1.00000000000000, -0.51035327095184, -0.31863563325245,
  287.           -0.20256413484477,  0.14728154134330,  0.38952639978999,
  288.           -0.23313271880868, -0.05246019024463, -0.02505961724053,
  289.            0.02442357316099,  0.01818801111503 },
  290.         {  0.95856916599601, -1.91713833199203,  0.95856916599601 },
  291.         {  1.00000000000000, -1.91542108074780,  0.91885558323625 },
  292.     },
  293.     {
  294.         8000,
  295.         {  0.53648789255105, -0.42163034350696, -0.00275953611929,
  296.            0.04267842219415, -0.10214864179676,  0.14590772289388,
  297.           -0.02459864859345, -0.11202315195388, -0.04060034127000,
  298.            0.04788665548180, -0.02217936801134 },
  299.         {  1.00000000000000, -0.25049871956020, -0.43193942311114,
  300.           -0.03424681017675, -0.04678328784242,  0.26408300200955,
  301.            0.15113130533216, -0.17556493366449, -0.18823009262115,
  302.            0.05477720428674,  0.04704409688120 },
  303.         {  0.94597685600279, -1.89195371200558,  0.94597685600279 },
  304.         {  1.00000000000000, -1.88903307939452,  0.89487434461664 },
  305.     },
  306. };
  307.  
  308. typedef struct ReplayGainContext {
  309.     uint32_t histogram[HISTOGRAM_SLOTS];
  310.     float peak;
  311.     int yule_hist_i, butter_hist_i;
  312.     const double *yule_coeff_a;
  313.     const double *yule_coeff_b;
  314.     const double *butter_coeff_a;
  315.     const double *butter_coeff_b;
  316.     float yule_hist_a[256];
  317.     float yule_hist_b[256];
  318.     float butter_hist_a[256];
  319.     float butter_hist_b[256];
  320. } ReplayGainContext;
  321.  
  322. static int query_formats(AVFilterContext *ctx)
  323. {
  324.     AVFilterFormats *formats = NULL;
  325.     AVFilterChannelLayouts *layout = NULL;
  326.     int i;
  327.  
  328.     ff_add_format(&formats, AV_SAMPLE_FMT_FLT);
  329.     ff_set_common_formats(ctx, formats);
  330.     ff_add_channel_layout(&layout, AV_CH_LAYOUT_STEREO);
  331.     ff_set_common_channel_layouts(ctx, layout);
  332.  
  333.     formats = NULL;
  334.     for (i = 0; i < FF_ARRAY_ELEMS(freqinfos); i++)
  335.         ff_add_format(&formats, freqinfos[i].sample_rate);
  336.     ff_set_common_samplerates(ctx, formats);
  337.  
  338.     return 0;
  339. }
  340.  
  341. static int config_input(AVFilterLink *inlink)
  342. {
  343.     AVFilterContext *ctx = inlink->dst;
  344.     ReplayGainContext *s = ctx->priv;
  345.     int i;
  346.  
  347.     for (i = 0; i < FF_ARRAY_ELEMS(freqinfos); i++) {
  348.         if (freqinfos[i].sample_rate == inlink->sample_rate)
  349.             break;
  350.     }
  351.     av_assert0(i < FF_ARRAY_ELEMS(freqinfos));
  352.  
  353.     s->yule_coeff_a   = freqinfos[i].AYule;
  354.     s->yule_coeff_b   = freqinfos[i].BYule;
  355.     s->butter_coeff_a = freqinfos[i].AButter;
  356.     s->butter_coeff_b = freqinfos[i].BButter;
  357.  
  358.     s->yule_hist_i   = 20;
  359.     s->butter_hist_i = 4;
  360.     inlink->partial_buf_size =
  361.     inlink->min_samples =
  362.     inlink->max_samples = inlink->sample_rate / 20;
  363.  
  364.     return 0;
  365. }
  366.  
  367. /*
  368.  * Update largest absolute sample value.
  369.  */
  370. static void calc_stereo_peak(const float *samples, int nb_samples,
  371.                              float *peak_p)
  372. {
  373.     float peak = 0.0;
  374.  
  375.     while (nb_samples--) {
  376.         if (samples[0] > peak)
  377.             peak = samples[0];
  378.         else if (-samples[0] > peak)
  379.             peak = -samples[0];
  380.  
  381.         if (samples[1] > peak)
  382.             peak = samples[1];
  383.         else if (-samples[1] > peak)
  384.             peak = -samples[1];
  385.  
  386.         samples += 2;
  387.     }
  388.  
  389.     *peak_p = FFMAX(peak, *peak_p);
  390. }
  391.  
  392. /*
  393.  * Calculate stereo RMS level. Minimum value is about -100 dB for
  394.  * digital silence. The 90 dB offset is to compensate for the
  395.  * normalized float range and 3 dB is for stereo samples.
  396.  */
  397. static double calc_stereo_rms(const float *samples, int nb_samples)
  398. {
  399.     int count = nb_samples;
  400.     double sum = 1e-16;
  401.  
  402.     while (count--) {
  403.         sum += samples[0] * samples[0] + samples[1] * samples[1];
  404.         samples += 2;
  405.     }
  406.  
  407.     return 10 * log10 (sum / nb_samples) + 90.0 - 3.0;
  408. }
  409.  
  410. /*
  411.  * Optimized implementation of 2nd-order IIR stereo filter.
  412.  */
  413. static void butter_filter_stereo_samples(ReplayGainContext *s,
  414.                                          float *samples, int nb_samples)
  415. {
  416.     const double *coeff_a = s->butter_coeff_a;
  417.     const double *coeff_b = s->butter_coeff_b;
  418.     float *hist_a   = s->butter_hist_a;
  419.     float *hist_b   = s->butter_hist_b;
  420.     double left, right;
  421.     int i, j;
  422.  
  423.     i = s->butter_hist_i;
  424.  
  425.     // If filter history is very small magnitude, clear it completely
  426.     // to prevent denormals from rattling around in there forever
  427.     // (slowing us down).
  428.  
  429.     for (j = -4; j < 0; ++j)
  430.         if (fabs(hist_a[i + j]) > 1e-10 || fabs(hist_b[i + j]) > 1e-10)
  431.             break;
  432.  
  433.     if (!j) {
  434.         memset(s->butter_hist_a, 0, sizeof(s->butter_hist_a));
  435.         memset(s->butter_hist_b, 0, sizeof(s->butter_hist_b));
  436.     }
  437.  
  438.     while (nb_samples--) {
  439.         left   = (hist_b[i    ] = samples[0]) * coeff_b[0];
  440.         right  = (hist_b[i + 1] = samples[1]) * coeff_b[0];
  441.         left  += hist_b[i - 2] * coeff_b[1] - hist_a[i - 2] * coeff_a[1];
  442.         right += hist_b[i - 1] * coeff_b[1] - hist_a[i - 1] * coeff_a[1];
  443.         left  += hist_b[i - 4] * coeff_b[2] - hist_a[i - 4] * coeff_a[2];
  444.         right += hist_b[i - 3] * coeff_b[2] - hist_a[i - 3] * coeff_a[2];
  445.         samples[0] = hist_a[i    ] = (float) left;
  446.         samples[1] = hist_a[i + 1] = (float) right;
  447.         samples += 2;
  448.  
  449.         if ((i += 2) == 256) {
  450.             memcpy(hist_a, hist_a + 252, sizeof(*hist_a) * 4);
  451.             memcpy(hist_b, hist_b + 252, sizeof(*hist_b) * 4);
  452.             i = 4;
  453.         }
  454.     }
  455.  
  456.     s->butter_hist_i = i;
  457. }
  458.  
  459. /*
  460.  * Optimized implementation of 10th-order IIR stereo filter.
  461.  */
  462. static void yule_filter_stereo_samples(ReplayGainContext *s, const float *src,
  463.                                        float *dst, int nb_samples)
  464. {
  465.     const double *coeff_a = s->yule_coeff_a;
  466.     const double *coeff_b = s->yule_coeff_b;
  467.     float *hist_a   = s->yule_hist_a;
  468.     float *hist_b   = s->yule_hist_b;
  469.     double left, right;
  470.     int i, j;
  471.  
  472.     i = s->yule_hist_i;
  473.  
  474.     // If filter history is very small magnitude, clear it completely to
  475.     // prevent denormals from rattling around in there forever
  476.     // (slowing us down).
  477.  
  478.     for (j = -20; j < 0; ++j)
  479.         if (fabs(hist_a[i + j]) > 1e-10 || fabs(hist_b[i + j]) > 1e-10)
  480.             break;
  481.  
  482.     if (!j) {
  483.         memset(s->yule_hist_a, 0, sizeof(s->yule_hist_a));
  484.         memset(s->yule_hist_b, 0, sizeof(s->yule_hist_b));
  485.     }
  486.  
  487.     while (nb_samples--) {
  488.         left   = (hist_b[i] = src[0]) * coeff_b[0];
  489.         right  = (hist_b[i + 1] = src[1]) * coeff_b[0];
  490.         left  += hist_b[i -  2] * coeff_b[ 1] - hist_a[i -  2] * coeff_a[1 ];
  491.         right += hist_b[i -  1] * coeff_b[ 1] - hist_a[i -  1] * coeff_a[1 ];
  492.         left  += hist_b[i -  4] * coeff_b[ 2] - hist_a[i -  4] * coeff_a[2 ];
  493.         right += hist_b[i -  3] * coeff_b[ 2] - hist_a[i -  3] * coeff_a[2 ];
  494.         left  += hist_b[i -  6] * coeff_b[ 3] - hist_a[i -  6] * coeff_a[3 ];
  495.         right += hist_b[i -  5] * coeff_b[ 3] - hist_a[i -  5] * coeff_a[3 ];
  496.         left  += hist_b[i -  8] * coeff_b[ 4] - hist_a[i -  8] * coeff_a[4 ];
  497.         right += hist_b[i -  7] * coeff_b[ 4] - hist_a[i -  7] * coeff_a[4 ];
  498.         left  += hist_b[i - 10] * coeff_b[ 5] - hist_a[i - 10] * coeff_a[5 ];
  499.         right += hist_b[i -  9] * coeff_b[ 5] - hist_a[i -  9] * coeff_a[5 ];
  500.         left  += hist_b[i - 12] * coeff_b[ 6] - hist_a[i - 12] * coeff_a[6 ];
  501.         right += hist_b[i - 11] * coeff_b[ 6] - hist_a[i - 11] * coeff_a[6 ];
  502.         left  += hist_b[i - 14] * coeff_b[ 7] - hist_a[i - 14] * coeff_a[7 ];
  503.         right += hist_b[i - 13] * coeff_b[ 7] - hist_a[i - 13] * coeff_a[7 ];
  504.         left  += hist_b[i - 16] * coeff_b[ 8] - hist_a[i - 16] * coeff_a[8 ];
  505.         right += hist_b[i - 15] * coeff_b[ 8] - hist_a[i - 15] * coeff_a[8 ];
  506.         left  += hist_b[i - 18] * coeff_b[ 9] - hist_a[i - 18] * coeff_a[9 ];
  507.         right += hist_b[i - 17] * coeff_b[ 9] - hist_a[i - 17] * coeff_a[9 ];
  508.         left  += hist_b[i - 20] * coeff_b[10] - hist_a[i - 20] * coeff_a[10];
  509.         right += hist_b[i - 19] * coeff_b[10] - hist_a[i - 19] * coeff_a[10];
  510.         dst[0] = hist_a[i    ] = (float)left;
  511.         dst[1] = hist_a[i + 1] = (float)right;
  512.         src += 2;
  513.         dst += 2;
  514.  
  515.         if ((i += 2) == 256) {
  516.             memcpy(hist_a, hist_a + 236, sizeof(*hist_a) * 20);
  517.             memcpy(hist_b, hist_b + 236, sizeof(*hist_b) * 20);
  518.             i = 20;
  519.         }
  520.     }
  521.  
  522.     s->yule_hist_i = i;
  523. }
  524.  
  525. /*
  526.  * Calculate the ReplayGain value from the specified loudness histogram;
  527.  * clip to -24 / +64 dB.
  528.  */
  529. static float calc_replaygain(uint32_t *histogram)
  530. {
  531.     uint32_t loud_count = 0, total_windows = 0;
  532.     float gain;
  533.     int i;
  534.  
  535.     for (i = 0; i < HISTOGRAM_SLOTS; i++)
  536.         total_windows += histogram [i];
  537.  
  538.     while (i--)
  539.         if ((loud_count += histogram [i]) * 20 >= total_windows)
  540.             break;
  541.  
  542.     gain = (float)(64.54 - i / 100.0);
  543.  
  544.     return av_clipf(gain, -24.0, 64.0);
  545. }
  546.  
  547. static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  548. {
  549.     AVFilterContext *ctx = inlink->dst;
  550.     AVFilterLink *outlink = ctx->outputs[0];
  551.     ReplayGainContext *s = ctx->priv;
  552.     uint32_t level;
  553.     AVFrame *out;
  554.  
  555.     out = ff_get_audio_buffer(inlink, in->nb_samples);
  556.     if (!out) {
  557.         av_frame_free(&in);
  558.         return AVERROR(ENOMEM);
  559.     }
  560.  
  561.     calc_stereo_peak((float *)in->data[0],
  562.                               in->nb_samples, &s->peak);
  563.     yule_filter_stereo_samples(s, (const float *)in->data[0],
  564.                                         (float *)out->data[0],
  565.                                                  out->nb_samples);
  566.     butter_filter_stereo_samples(s, (float *)out->data[0],
  567.                                              out->nb_samples);
  568.     level = (uint32_t)floor(100 * calc_stereo_rms((float *)out->data[0],
  569.                                                            out->nb_samples));
  570.     level = av_clip(level, 0, HISTOGRAM_SLOTS - 1);
  571.  
  572.     s->histogram[level]++;
  573.  
  574.     av_frame_free(&out);
  575.     return ff_filter_frame(outlink, in);
  576. }
  577.  
  578. static av_cold void uninit(AVFilterContext *ctx)
  579. {
  580.     ReplayGainContext *s = ctx->priv;
  581.     float gain = calc_replaygain(s->histogram);
  582.  
  583.     av_log(ctx, AV_LOG_INFO, "track_gain = %+.2f dB\n", gain);
  584.     av_log(ctx, AV_LOG_INFO, "track_peak = %.6f\n", s->peak);
  585. }
  586.  
  587. static const AVFilterPad replaygain_inputs[] = {
  588.     {
  589.         .name         = "default",
  590.         .type         = AVMEDIA_TYPE_AUDIO,
  591.         .filter_frame = filter_frame,
  592.         .config_props = config_input,
  593.     },
  594.     { NULL }
  595. };
  596.  
  597. static const AVFilterPad replaygain_outputs[] = {
  598.     {
  599.         .name = "default",
  600.         .type = AVMEDIA_TYPE_AUDIO,
  601.     },
  602.     { NULL }
  603. };
  604.  
  605. AVFilter avfilter_af_replaygain = {
  606.     .name          = "replaygain",
  607.     .description   = NULL_IF_CONFIG_SMALL("ReplayGain scanner."),
  608.     .query_formats = query_formats,
  609.     .uninit        = uninit,
  610.     .priv_size     = sizeof(ReplayGainContext),
  611.     .inputs        = replaygain_inputs,
  612.     .outputs       = replaygain_outputs,
  613. };
  614.