/*
  * Copyright (c) 2012 Clément Bœsch
  *
  * This file is part of FFmpeg.
  *

  * FFmpeg 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.

  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */
 
 /**
  * @file
  * EBU R.128 implementation
  * @see http://tech.ebu.ch/loudness
  * @see https://www.youtube.com/watch?v=iuEtQqC-Sqo "EBU R128 Introduction - Florian Camerer"
  * @todo implement start/stop/reset through filter command injection
  * @todo support other frequencies to avoid resampling
  */
 
 #include <math.h>
 
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"

 #include "libavutil/channel_layout.h"

 #include "libavutil/dict.h"

 #include "libavutil/ffmath.h"

 #include "libavutil/xga_font_data.h"
 #include "libavutil/opt.h"
 #include "libavutil/timestamp.h"

 #include "libswresample/swresample.h"

 #include "audio.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 
 #define MAX_CHANNELS 63
 
 /* pre-filter coefficients */
 #define PRE_B0  1.53512485958697
 #define PRE_B1 -2.69169618940638
 #define PRE_B2  1.19839281085285
 #define PRE_A1 -1.69065929318241
 #define PRE_A2  0.73248077421585
 
 /* RLB-filter coefficients */
 #define RLB_B0  1.0
 #define RLB_B1 -2.0
 #define RLB_B2  1.0
 #define RLB_A1 -1.99004745483398
 #define RLB_A2  0.99007225036621
 
 #define ABS_THRES    -70            ///< silence gate: we discard anything below this absolute (LUFS) threshold
 #define ABS_UP_THRES  10            ///< upper loud limit to consider (ABS_THRES being the minimum)
 #define HIST_GRAIN   100            ///< defines histogram precision
 #define HIST_SIZE  ((ABS_UP_THRES - ABS_THRES) * HIST_GRAIN + 1)
 
 /**

  * A histogram is an array of HIST_SIZE hist_entry storing all the energies

  * recorded (with an accuracy of 1/HIST_GRAIN) of the loudnesses from ABS_THRES
  * (at 0) to ABS_UP_THRES (at HIST_SIZE-1).
  * This fixed-size system avoids the need of a list of energies growing
  * infinitely over the time and is thus more scalable.
  */
 struct hist_entry {
     int count;                      ///< how many times the corresponding value occurred
     double energy;                  ///< E = 10^((L + 0.691) / 10)
     double loudness;                ///< L = -0.691 + 10 * log10(E)
 };
 
 struct integrator {
     double *cache[MAX_CHANNELS];    ///< window of filtered samples (N ms)
     int cache_pos;                  ///< focus on the last added bin in the cache array
     double sum[MAX_CHANNELS];       ///< sum of the last N ms filtered samples (cache content)
     int filled;                     ///< 1 if the cache is completely filled, 0 otherwise
     double rel_threshold;           ///< relative threshold
     double sum_kept_powers;         ///< sum of the powers (weighted sums) above absolute threshold
     int nb_kept_powers;             ///< number of sum above absolute threshold
     struct hist_entry *histogram;   ///< histogram of the powers, used to compute LRA and I
 };
 
 struct rect { int x, y, w, h; };
 

 typedef struct EBUR128Context {

     const AVClass *class;           ///< AVClass context for log and options purpose
 

     /* peak metering */
     int peak_mode;                  ///< enabled peak modes
     double *true_peaks;             ///< true peaks per channel
     double *sample_peaks;           ///< sample peaks per channel

     double *true_peaks_per_frame;   ///< true peaks in a frame per channel

 #if CONFIG_SWRESAMPLE
     SwrContext *swr_ctx;            ///< over-sampling context for true peak metering
     double *swr_buf;                ///< resampled audio data for true peak metering
     int swr_linesize;
 #endif
 

     /* video  */
     int do_video;                   ///< 1 if video output enabled, 0 otherwise
     int w, h;                       ///< size of the video output
     struct rect text;               ///< rectangle for the LU legend on the left
     struct rect graph;              ///< rectangle for the main graph in the center
     struct rect gauge;              ///< rectangle for the gauge on the right

     AVFrame *outpicref;             ///< output picture reference, updated regularly

     int meter;                      ///< select a EBU mode between +9 and +18
     int scale_range;                ///< the range of LU values according to the meter
     int y_zero_lu;                  ///< the y value (pixel position) for 0 LU
     int *y_line_ref;                ///< y reference values for drawing the LU lines in the graph and the gauge
 
     /* audio */
     int nb_channels;                ///< number of channels in the input
     double *ch_weighting;           ///< channel weighting mapping
     int sample_count;               ///< sample count used for refresh frequency, reset at refresh
 
     /* Filter caches.
      * The mult by 3 in the following is for X[i], X[i-1] and X[i-2] */
     double x[MAX_CHANNELS * 3];     ///< 3 input samples cache for each channel
     double y[MAX_CHANNELS * 3];     ///< 3 pre-filter samples cache for each channel
     double z[MAX_CHANNELS * 3];     ///< 3 RLB-filter samples cache for each channel
 
 #define I400_BINS  (48000 * 4 / 10)
 #define I3000_BINS (48000 * 3)
     struct integrator i400;         ///< 400ms integrator, used for Momentary loudness  (M), and Integrated loudness (I)
     struct integrator i3000;        ///<    3s integrator, used for Short term loudness (S), and Loudness Range      (LRA)
 
     /* I and LRA specific */
     double integrated_loudness;     ///< integrated loudness in LUFS (I)
     double loudness_range;          ///< loudness range in LU (LRA)
     double lra_low, lra_high;       ///< low and high LRA values

 
     /* misc */
     int loglevel;                   ///< log level for frame logging

     int metadata;                   ///< whether or not to inject loudness results in frames

     int dual_mono;                  ///< whether or not to treat single channel input files as dual-mono

     double pan_law;                 ///< pan law value used to calculate dual-mono measurements

 } EBUR128Context;
 

 enum {
     PEAK_MODE_NONE          = 0,
     PEAK_MODE_SAMPLES_PEAKS = 1<<1,
     PEAK_MODE_TRUE_PEAKS    = 1<<2,
 };
 

 #define OFFSET(x) offsetof(EBUR128Context, x)
 #define A AV_OPT_FLAG_AUDIO_PARAM
 #define V AV_OPT_FLAG_VIDEO_PARAM
 #define F AV_OPT_FLAG_FILTERING_PARAM
 static const AVOption ebur128_options[] = {

     { "video", "set video output", OFFSET(do_video), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, V|F },

     { "size",  "set video size",   OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, V|F },
     { "meter", "set scale meter (+9 to +18)",  OFFSET(meter), AV_OPT_TYPE_INT, {.i64 = 9}, 9, 18, V|F },

     { "framelog", "force frame logging level", OFFSET(loglevel), AV_OPT_TYPE_INT, {.i64 = -1},   INT_MIN, INT_MAX, A|V|F, "level" },
         { "info",    "information logging level", 0, AV_OPT_TYPE_CONST, {.i64 = AV_LOG_INFO},    INT_MIN, INT_MAX, A|V|F, "level" },
         { "verbose", "verbose logging level",     0, AV_OPT_TYPE_CONST, {.i64 = AV_LOG_VERBOSE}, INT_MIN, INT_MAX, A|V|F, "level" },

     { "metadata", "inject metadata in the filtergraph", OFFSET(metadata), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, A|V|F },

     { "peak", "set peak mode", OFFSET(peak_mode), AV_OPT_TYPE_FLAGS, {.i64 = PEAK_MODE_NONE}, 0, INT_MAX, A|F, "mode" },
         { "none",   "disable any peak mode",   0, AV_OPT_TYPE_CONST, {.i64 = PEAK_MODE_NONE},          INT_MIN, INT_MAX, A|F, "mode" },
         { "sample", "enable peak-sample mode", 0, AV_OPT_TYPE_CONST, {.i64 = PEAK_MODE_SAMPLES_PEAKS}, INT_MIN, INT_MAX, A|F, "mode" },
         { "true",   "enable true-peak mode",   0, AV_OPT_TYPE_CONST, {.i64 = PEAK_MODE_TRUE_PEAKS},    INT_MIN, INT_MAX, A|F, "mode" },

     { "dualmono", "treat mono input files as dual-mono", OFFSET(dual_mono), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, A|F },
     { "panlaw", "set a specific pan law for dual-mono files", OFFSET(pan_law), AV_OPT_TYPE_DOUBLE, {.dbl = -3.01029995663978}, -10.0, 0.0, A|F },

     { NULL },

 };
 
 AVFILTER_DEFINE_CLASS(ebur128);
 
 static const uint8_t graph_colors[] = {
     0xdd, 0x66, 0x66,   // value above 0LU non reached
     0x66, 0x66, 0xdd,   // value below 0LU non reached
     0x96, 0x33, 0x33,   // value above 0LU reached
     0x33, 0x33, 0x96,   // value below 0LU reached
     0xdd, 0x96, 0x96,   // value above 0LU line non reached
     0x96, 0x96, 0xdd,   // value below 0LU line non reached
     0xdd, 0x33, 0x33,   // value above 0LU line reached
     0x33, 0x33, 0xdd,   // value below 0LU line reached
 };
 
 static const uint8_t *get_graph_color(const EBUR128Context *ebur128, int v, int y)
 {
     const int below0  = y > ebur128->y_zero_lu;
     const int reached = y >= v;
     const int line    = ebur128->y_line_ref[y] || y == ebur128->y_zero_lu;
     const int colorid = 4*line + 2*reached + below0;
     return graph_colors + 3*colorid;
 }
 
 static inline int lu_to_y(const EBUR128Context *ebur128, double v)
 {
     v += 2 * ebur128->meter;                            // make it in range [0;...]
     v  = av_clipf(v, 0, ebur128->scale_range);          // make sure it's in the graph scale
     v  = ebur128->scale_range - v;                      // invert value (y=0 is on top)
     return v * ebur128->graph.h / ebur128->scale_range; // rescale from scale range to px height
 }
 
 #define FONT8   0
 #define FONT16  1
 
 static const uint8_t font_colors[] = {
     0xdd, 0xdd, 0x00,
     0x00, 0x96, 0x96,
 };
 

 static void drawtext(AVFrame *pic, int x, int y, int ftid, const uint8_t *color, const char *fmt, ...)

 {
     int i;
     char buf[128] = {0};
     const uint8_t *font;
     int font_height;
     va_list vl;
 
     if      (ftid == FONT16) font = avpriv_vga16_font, font_height = 16;
     else if (ftid == FONT8)  font = avpriv_cga_font,   font_height =  8;
     else return;
 
     va_start(vl, fmt);
     vsnprintf(buf, sizeof(buf), fmt, vl);
     va_end(vl);
 
     for (i = 0; buf[i]; i++) {
         int char_y, mask;
         uint8_t *p = pic->data[0] + y*pic->linesize[0] + (x + i*8)*3;
 
         for (char_y = 0; char_y < font_height; char_y++) {
             for (mask = 0x80; mask; mask >>= 1) {
                 if (font[buf[i] * font_height + char_y] & mask)
                     memcpy(p, color, 3);
                 else
                     memcpy(p, "\x00\x00\x00", 3);
                 p += 3;
             }
             p += pic->linesize[0] - 8*3;
         }
     }
 }
 

 static void drawline(AVFrame *pic, int x, int y, int len, int step)

 {
     int i;
     uint8_t *p = pic->data[0] + y*pic->linesize[0] + x*3;
 
     for (i = 0; i < len; i++) {
         memcpy(p, "\x00\xff\x00", 3);
         p += step;
     }
 }
 
 static int config_video_output(AVFilterLink *outlink)
 {
     int i, x, y;
     uint8_t *p;
     AVFilterContext *ctx = outlink->src;
     EBUR128Context *ebur128 = ctx->priv;

     AVFrame *outpicref;

 
     /* check if there is enough space to represent everything decently */
     if (ebur128->w < 640 || ebur128->h < 480) {
         av_log(ctx, AV_LOG_ERROR, "Video size %dx%d is too small, "
                "minimum size is 640x480\n", ebur128->w, ebur128->h);
         return AVERROR(EINVAL);
     }
     outlink->w = ebur128->w;
     outlink->h = ebur128->h;

     outlink->sample_aspect_ratio = (AVRational){1,1};

 
 #define PAD 8
 
     /* configure text area position and size */
     ebur128->text.x  = PAD;
     ebur128->text.y  = 40;
     ebur128->text.w  = 3 * 8;   // 3 characters
     ebur128->text.h  = ebur128->h - PAD - ebur128->text.y;
 
     /* configure gauge position and size */
     ebur128->gauge.w = 20;
     ebur128->gauge.h = ebur128->text.h;
     ebur128->gauge.x = ebur128->w - PAD - ebur128->gauge.w;
     ebur128->gauge.y = ebur128->text.y;
 
     /* configure graph position and size */
     ebur128->graph.x = ebur128->text.x + ebur128->text.w + PAD;
     ebur128->graph.y = ebur128->gauge.y;
     ebur128->graph.w = ebur128->gauge.x - ebur128->graph.x - PAD;
     ebur128->graph.h = ebur128->gauge.h;
 
     /* graph and gauge share the LU-to-pixel code */
     av_assert0(ebur128->graph.h == ebur128->gauge.h);
 
     /* prepare the initial picref buffer */

     av_frame_free(&ebur128->outpicref);

     ebur128->outpicref = outpicref =

         ff_get_video_buffer(outlink, outlink->w, outlink->h);

     if (!outpicref)
         return AVERROR(ENOMEM);

     outpicref->sample_aspect_ratio = (AVRational){1,1};

 
     /* init y references values (to draw LU lines) */
     ebur128->y_line_ref = av_calloc(ebur128->graph.h + 1, sizeof(*ebur128->y_line_ref));
     if (!ebur128->y_line_ref)
         return AVERROR(ENOMEM);
 
     /* black background */
     memset(outpicref->data[0], 0, ebur128->h * outpicref->linesize[0]);
 
     /* draw LU legends */
     drawtext(outpicref, PAD, PAD+16, FONT8, font_colors+3, " LU");
     for (i = ebur128->meter; i >= -ebur128->meter * 2; i--) {
         y = lu_to_y(ebur128, i);
         x = PAD + (i < 10 && i > -10) * 8;
         ebur128->y_line_ref[y] = i;
         y -= 4; // -4 to center vertically
         drawtext(outpicref, x, y + ebur128->graph.y, FONT8, font_colors+3,
                  "%c%d", i < 0 ? '-' : i > 0 ? '+' : ' ', FFABS(i));
     }
 
     /* draw graph */
     ebur128->y_zero_lu = lu_to_y(ebur128, 0);
     p = outpicref->data[0] + ebur128->graph.y * outpicref->linesize[0]
                            + ebur128->graph.x * 3;
     for (y = 0; y < ebur128->graph.h; y++) {
         const uint8_t *c = get_graph_color(ebur128, INT_MAX, y);
 
         for (x = 0; x < ebur128->graph.w; x++)
             memcpy(p + x*3, c, 3);
         p += outpicref->linesize[0];
     }
 
     /* draw fancy rectangles around the graph and the gauge */
 #define DRAW_RECT(r) do { \
     drawline(outpicref, r.x,       r.y - 1,   r.w, 3); \
     drawline(outpicref, r.x,       r.y + r.h, r.w, 3); \
     drawline(outpicref, r.x - 1,   r.y,       r.h, outpicref->linesize[0]); \
     drawline(outpicref, r.x + r.w, r.y,       r.h, outpicref->linesize[0]); \
 } while (0)
     DRAW_RECT(ebur128->graph);
     DRAW_RECT(ebur128->gauge);
 
     return 0;
 }
 

 static int config_audio_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     EBUR128Context *ebur128 = ctx->priv;
 

     /* Force 100ms framing in case of metadata injection: the frames must have
      * a granularity of the window overlap to be accurately exploited.
      * As for the true peaks mode, it just simplifies the resampling buffer
      * allocation and the lookup in it (since sample buffers differ in size, it
      * can be more complex to integrate in the one-sample loop of
      * filter_frame()). */
     if (ebur128->metadata || (ebur128->peak_mode & PEAK_MODE_TRUE_PEAKS))

         inlink->min_samples =
         inlink->max_samples =
         inlink->partial_buf_size = inlink->sample_rate / 10;
     return 0;
 }
 

 static int config_audio_output(AVFilterLink *outlink)
 {
     int i;
     AVFilterContext *ctx = outlink->src;
     EBUR128Context *ebur128 = ctx->priv;
     const int nb_channels = av_get_channel_layout_nb_channels(outlink->channel_layout);
 
 #define BACK_MASK (AV_CH_BACK_LEFT    |AV_CH_BACK_CENTER    |AV_CH_BACK_RIGHT| \

                    AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_CENTER|AV_CH_TOP_BACK_RIGHT| \
                    AV_CH_SIDE_LEFT                          |AV_CH_SIDE_RIGHT| \
                    AV_CH_SURROUND_DIRECT_LEFT               |AV_CH_SURROUND_DIRECT_RIGHT)

 
     ebur128->nb_channels  = nb_channels;
     ebur128->ch_weighting = av_calloc(nb_channels, sizeof(*ebur128->ch_weighting));
     if (!ebur128->ch_weighting)
         return AVERROR(ENOMEM);
 
     for (i = 0; i < nb_channels; i++) {
         /* channel weighting */

         const uint16_t chl = av_channel_layout_extract_channel(outlink->channel_layout, i);
         if (chl & (AV_CH_LOW_FREQUENCY|AV_CH_LOW_FREQUENCY_2)) {

             ebur128->ch_weighting[i] = 0;

         } else if (chl & BACK_MASK) {

             ebur128->ch_weighting[i] = 1.41;

         } else {

             ebur128->ch_weighting[i] = 1.0;

         }
 
         if (!ebur128->ch_weighting[i])
             continue;

 
         /* bins buffer for the two integration window (400ms and 3s) */
         ebur128->i400.cache[i]  = av_calloc(I400_BINS,  sizeof(*ebur128->i400.cache[0]));
         ebur128->i3000.cache[i] = av_calloc(I3000_BINS, sizeof(*ebur128->i3000.cache[0]));
         if (!ebur128->i400.cache[i] || !ebur128->i3000.cache[i])
             return AVERROR(ENOMEM);
     }
 

 #if CONFIG_SWRESAMPLE
     if (ebur128->peak_mode & PEAK_MODE_TRUE_PEAKS) {
         int ret;
 

         ebur128->swr_buf    = av_malloc_array(nb_channels, 19200 * sizeof(double));

         ebur128->true_peaks = av_calloc(nb_channels, sizeof(*ebur128->true_peaks));

         ebur128->true_peaks_per_frame = av_calloc(nb_channels, sizeof(*ebur128->true_peaks_per_frame));

         ebur128->swr_ctx    = swr_alloc();

         if (!ebur128->swr_buf || !ebur128->true_peaks ||
             !ebur128->true_peaks_per_frame || !ebur128->swr_ctx)

             return AVERROR(ENOMEM);
 
         av_opt_set_int(ebur128->swr_ctx, "in_channel_layout",    outlink->channel_layout, 0);
         av_opt_set_int(ebur128->swr_ctx, "in_sample_rate",       outlink->sample_rate, 0);
         av_opt_set_sample_fmt(ebur128->swr_ctx, "in_sample_fmt", outlink->format, 0);
 
         av_opt_set_int(ebur128->swr_ctx, "out_channel_layout",    outlink->channel_layout, 0);
         av_opt_set_int(ebur128->swr_ctx, "out_sample_rate",       192000, 0);
         av_opt_set_sample_fmt(ebur128->swr_ctx, "out_sample_fmt", outlink->format, 0);
 
         ret = swr_init(ebur128->swr_ctx);
         if (ret < 0)
             return ret;
     }
 #endif
 
     if (ebur128->peak_mode & PEAK_MODE_SAMPLES_PEAKS) {
         ebur128->sample_peaks = av_calloc(nb_channels, sizeof(*ebur128->sample_peaks));
         if (!ebur128->sample_peaks)
             return AVERROR(ENOMEM);
     }
 

     return 0;
 }
 

 #define ENERGY(loudness) (ff_exp10(((loudness) + 0.691) / 10.))

 #define LOUDNESS(energy) (-0.691 + 10 * log10(energy))

 #define DBFS(energy) (20 * log10(energy))

 
 static struct hist_entry *get_histogram(void)
 {
     int i;
     struct hist_entry *h = av_calloc(HIST_SIZE, sizeof(*h));
 

     if (!h)
         return NULL;

     for (i = 0; i < HIST_SIZE; i++) {
         h[i].loudness = i / (double)HIST_GRAIN + ABS_THRES;
         h[i].energy   = ENERGY(h[i].loudness);
     }
     return h;
 }
 

 static av_cold int init(AVFilterContext *ctx)

 {
     EBUR128Context *ebur128 = ctx->priv;
     AVFilterPad pad;
 

     if (ebur128->loglevel != AV_LOG_INFO &&
         ebur128->loglevel != AV_LOG_VERBOSE) {

         if (ebur128->do_video || ebur128->metadata)

             ebur128->loglevel = AV_LOG_VERBOSE;
         else
             ebur128->loglevel = AV_LOG_INFO;
     }
 

     if (!CONFIG_SWRESAMPLE && (ebur128->peak_mode & PEAK_MODE_TRUE_PEAKS)) {
         av_log(ctx, AV_LOG_ERROR,
                "True-peak mode requires libswresample to be performed\n");
         return AVERROR(EINVAL);
     }
 

     // if meter is  +9 scale, scale range is from -18 LU to  +9 LU (or 3*9)
     // if meter is +18 scale, scale range is from -36 LU to +18 LU (or 3*18)
     ebur128->scale_range = 3 * ebur128->meter;
 
     ebur128->i400.histogram  = get_histogram();
     ebur128->i3000.histogram = get_histogram();

     if (!ebur128->i400.histogram || !ebur128->i3000.histogram)
         return AVERROR(ENOMEM);

 
     ebur128->integrated_loudness = ABS_THRES;
     ebur128->loudness_range = 0;
 
     /* insert output pads */
     if (ebur128->do_video) {
         pad = (AVFilterPad){
             .name         = av_strdup("out0"),
             .type         = AVMEDIA_TYPE_VIDEO,
             .config_props = config_video_output,
         };
         if (!pad.name)
             return AVERROR(ENOMEM);
         ff_insert_outpad(ctx, 0, &pad);
     }
     pad = (AVFilterPad){
         .name         = av_asprintf("out%d", ebur128->do_video),
         .type         = AVMEDIA_TYPE_AUDIO,
         .config_props = config_audio_output,
     };
     if (!pad.name)
         return AVERROR(ENOMEM);
     ff_insert_outpad(ctx, ebur128->do_video, &pad);
 
     /* summary */
     av_log(ctx, AV_LOG_VERBOSE, "EBU +%d scale\n", ebur128->meter);
 
     return 0;
 }
 
 #define HIST_POS(power) (int)(((power) - ABS_THRES) * HIST_GRAIN)
 
 /* loudness and power should be set such as loudness = -0.691 +
  * 10*log10(power), we just avoid doing that calculus two times */
 static int gate_update(struct integrator *integ, double power,
                        double loudness, int gate_thres)
 {
     int ipower;
     double relative_threshold;
     int gate_hist_pos;
 
     /* update powers histograms by incrementing current power count */
     ipower = av_clip(HIST_POS(loudness), 0, HIST_SIZE - 1);
     integ->histogram[ipower].count++;
 
     /* compute relative threshold and get its position in the histogram */
     integ->sum_kept_powers += power;
     integ->nb_kept_powers++;
     relative_threshold = integ->sum_kept_powers / integ->nb_kept_powers;
     if (!relative_threshold)
         relative_threshold = 1e-12;
     integ->rel_threshold = LOUDNESS(relative_threshold) + gate_thres;
     gate_hist_pos = av_clip(HIST_POS(integ->rel_threshold), 0, HIST_SIZE - 1);
 
     return gate_hist_pos;
 }
 

 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)

 {

     int i, ch, idx_insample;

     AVFilterContext *ctx = inlink->dst;
     EBUR128Context *ebur128 = ctx->priv;
     const int nb_channels = ebur128->nb_channels;

     const int nb_samples  = insamples->nb_samples;

     const double *samples = (double *)insamples->data[0];

     AVFrame *pic = ebur128->outpicref;

 #if CONFIG_SWRESAMPLE
     if (ebur128->peak_mode & PEAK_MODE_TRUE_PEAKS) {
         const double *swr_samples = ebur128->swr_buf;
         int ret = swr_convert(ebur128->swr_ctx, (uint8_t**)&ebur128->swr_buf, 19200,
                               (const uint8_t **)insamples->data, nb_samples);
         if (ret < 0)
             return ret;

         for (ch = 0; ch < nb_channels; ch++)
             ebur128->true_peaks_per_frame[ch] = 0.0;

         for (idx_insample = 0; idx_insample < ret; idx_insample++) {
             for (ch = 0; ch < nb_channels; ch++) {

                 ebur128->true_peaks[ch] = FFMAX(ebur128->true_peaks[ch], fabs(*swr_samples));

                 ebur128->true_peaks_per_frame[ch] = FFMAX(ebur128->true_peaks_per_frame[ch],

                                                           fabs(*swr_samples));

                 swr_samples++;
             }
         }
     }
 #endif
 

     for (idx_insample = 0; idx_insample < nb_samples; idx_insample++) {

         const int bin_id_400  = ebur128->i400.cache_pos;
         const int bin_id_3000 = ebur128->i3000.cache_pos;
 
 #define MOVE_TO_NEXT_CACHED_ENTRY(time) do {                \
     ebur128->i##time.cache_pos++;                           \
     if (ebur128->i##time.cache_pos == I##time##_BINS) {     \
         ebur128->i##time.filled    = 1;                     \
         ebur128->i##time.cache_pos = 0;                     \
     }                                                       \
 } while (0)
 
         MOVE_TO_NEXT_CACHED_ENTRY(400);
         MOVE_TO_NEXT_CACHED_ENTRY(3000);
 
         for (ch = 0; ch < nb_channels; ch++) {
             double bin;
 

             if (ebur128->peak_mode & PEAK_MODE_SAMPLES_PEAKS)

                 ebur128->sample_peaks[ch] = FFMAX(ebur128->sample_peaks[ch], fabs(*samples));

             ebur128->x[ch * 3] = *samples++; // set X[i]
 

             if (!ebur128->ch_weighting[ch])
                 continue;
 
             /* Y[i] = X[i]*b0 + X[i-1]*b1 + X[i-2]*b2 - Y[i-1]*a1 - Y[i-2]*a2 */
 #define FILTER(Y, X, name) do {                                                 \
             double *dst = ebur128->Y + ch*3;                                    \
             double *src = ebur128->X + ch*3;                                    \
             dst[2] = dst[1];                                                    \
             dst[1] = dst[0];                                                    \
             dst[0] = src[0]*name##_B0 + src[1]*name##_B1 + src[2]*name##_B2     \
                                       - dst[1]*name##_A1 - dst[2]*name##_A2;    \
 } while (0)
 
             // TODO: merge both filters in one?
             FILTER(y, x, PRE);  // apply pre-filter
             ebur128->x[ch * 3 + 2] = ebur128->x[ch * 3 + 1];
             ebur128->x[ch * 3 + 1] = ebur128->x[ch * 3    ];
             FILTER(z, y, RLB);  // apply RLB-filter
 
             bin = ebur128->z[ch * 3] * ebur128->z[ch * 3];
 
             /* add the new value, and limit the sum to the cache size (400ms or 3s)
              * by removing the oldest one */
             ebur128->i400.sum [ch] = ebur128->i400.sum [ch] + bin - ebur128->i400.cache [ch][bin_id_400];
             ebur128->i3000.sum[ch] = ebur128->i3000.sum[ch] + bin - ebur128->i3000.cache[ch][bin_id_3000];
 
             /* override old cache entry with the new value */
             ebur128->i400.cache [ch][bin_id_400 ] = bin;
             ebur128->i3000.cache[ch][bin_id_3000] = bin;
         }
 
         /* For integrated loudness, gating blocks are 400ms long with 75%
          * overlap (see BS.1770-2 p5), so a re-computation is needed each 100ms
          * (4800 samples at 48kHz). */
         if (++ebur128->sample_count == 4800) {
             double loudness_400, loudness_3000;
             double power_400 = 1e-12, power_3000 = 1e-12;
             AVFilterLink *outlink = ctx->outputs[0];
             const int64_t pts = insamples->pts +

                 av_rescale_q(idx_insample, (AVRational){ 1, inlink->sample_rate },

                              outlink->time_base);
 
             ebur128->sample_count = 0;
 
 #define COMPUTE_LOUDNESS(m, time) do {                                              \
     if (ebur128->i##time.filled) {                                                  \
         /* weighting sum of the last <time> ms */                                   \
         for (ch = 0; ch < nb_channels; ch++)                                        \
             power_##time += ebur128->ch_weighting[ch] * ebur128->i##time.sum[ch];   \
         power_##time /= I##time##_BINS;                                             \
     }                                                                               \
     loudness_##time = LOUDNESS(power_##time);                                       \
 } while (0)
 
             COMPUTE_LOUDNESS(M,  400);
             COMPUTE_LOUDNESS(S, 3000);
 
             /* Integrated loudness */
 #define I_GATE_THRES -10  // initially defined to -8 LU in the first EBU standard
 
             if (loudness_400 >= ABS_THRES) {
                 double integrated_sum = 0;
                 int nb_integrated = 0;
                 int gate_hist_pos = gate_update(&ebur128->i400, power_400,
                                                 loudness_400, I_GATE_THRES);
 
                 /* compute integrated loudness by summing the histogram values
                  * above the relative threshold */
                 for (i = gate_hist_pos; i < HIST_SIZE; i++) {
                     const int nb_v = ebur128->i400.histogram[i].count;
                     nb_integrated  += nb_v;
                     integrated_sum += nb_v * ebur128->i400.histogram[i].energy;
                 }

                 if (nb_integrated) {

                     ebur128->integrated_loudness = LOUDNESS(integrated_sum / nb_integrated);

                     /* dual-mono correction */
                     if (nb_channels == 1 && ebur128->dual_mono) {
                         ebur128->integrated_loudness -= ebur128->pan_law;
                     }

                 }

             }
 
             /* LRA */
 #define LRA_GATE_THRES -20
 #define LRA_LOWER_PRC   10
 #define LRA_HIGHER_PRC  95
 
             /* XXX: example code in EBU 3342 is ">=" but formula in BS.1770
              * specs is ">" */
             if (loudness_3000 >= ABS_THRES) {
                 int nb_powers = 0;
                 int gate_hist_pos = gate_update(&ebur128->i3000, power_3000,
                                                 loudness_3000, LRA_GATE_THRES);
 
                 for (i = gate_hist_pos; i < HIST_SIZE; i++)
                     nb_powers += ebur128->i3000.histogram[i].count;
                 if (nb_powers) {
                     int n, nb_pow;
 
                     /* get lower loudness to consider */
                     n = 0;
                     nb_pow = LRA_LOWER_PRC  * nb_powers / 100. + 0.5;
                     for (i = gate_hist_pos; i < HIST_SIZE; i++) {
                         n += ebur128->i3000.histogram[i].count;
                         if (n >= nb_pow) {
                             ebur128->lra_low = ebur128->i3000.histogram[i].loudness;
                             break;
                         }
                     }
 
                     /* get higher loudness to consider */
                     n = nb_powers;
                     nb_pow = LRA_HIGHER_PRC * nb_powers / 100. + 0.5;
                     for (i = HIST_SIZE - 1; i >= 0; i--) {
                         n -= ebur128->i3000.histogram[i].count;
                         if (n < nb_pow) {
                             ebur128->lra_high = ebur128->i3000.histogram[i].loudness;
                             break;
                         }
                     }
 
                     // XXX: show low & high on the graph?
                     ebur128->loudness_range = ebur128->lra_high - ebur128->lra_low;
                 }
             }
 

             /* dual-mono correction */
             if (nb_channels == 1 && ebur128->dual_mono) {
                 loudness_400 -= ebur128->pan_law;
                 loudness_3000 -= ebur128->pan_law;
             }
 

 #define LOG_FMT "M:%6.1f S:%6.1f     I:%6.1f LUFS     LRA:%6.1f LU"
 
             /* push one video frame */
             if (ebur128->do_video) {
                 int x, y, ret;
                 uint8_t *p;
 
                 const int y_loudness_lu_graph = lu_to_y(ebur128, loudness_3000 + 23);
                 const int y_loudness_lu_gauge = lu_to_y(ebur128, loudness_400  + 23);
 
                 /* draw the graph using the short-term loudness */
                 p = pic->data[0] + ebur128->graph.y*pic->linesize[0] + ebur128->graph.x*3;
                 for (y = 0; y < ebur128->graph.h; y++) {
                     const uint8_t *c = get_graph_color(ebur128, y_loudness_lu_graph, y);
 
                     memmove(p, p + 3, (ebur128->graph.w - 1) * 3);
                     memcpy(p + (ebur128->graph.w - 1) * 3, c, 3);
                     p += pic->linesize[0];
                 }
 
                 /* draw the gauge using the momentary loudness */
                 p = pic->data[0] + ebur128->gauge.y*pic->linesize[0] + ebur128->gauge.x*3;
                 for (y = 0; y < ebur128->gauge.h; y++) {
                     const uint8_t *c = get_graph_color(ebur128, y_loudness_lu_gauge, y);
 
                     for (x = 0; x < ebur128->gauge.w; x++)
                         memcpy(p + x*3, c, 3);
                     p += pic->linesize[0];
                 }
 
                 /* draw textual info */
                 drawtext(pic, PAD, PAD - PAD/2, FONT16, font_colors,
                          LOG_FMT "     ", // padding to erase trailing characters
                          loudness_400, loudness_3000,
                          ebur128->integrated_loudness, ebur128->loudness_range);
 
                 /* set pts and push frame */
                 pic->pts = pts;

                 ret = ff_filter_frame(outlink, av_frame_clone(pic));

                 if (ret < 0)

                     return ret;
             }
 

             if (ebur128->metadata) { /* happens only once per filter_frame call */
                 char metabuf[128];

 #define META_PREFIX "lavfi.r128."
 

 #define SET_META(name, var) do {                                            \
     snprintf(metabuf, sizeof(metabuf), "%.3f", var);                        \

     av_dict_set(&insamples->metadata, name, metabuf, 0);                    \

 } while (0)

 
 #define SET_META_PEAK(name, ptype) do {                                     \
     if (ebur128->peak_mode & PEAK_MODE_ ## ptype ## _PEAKS) {               \
         char key[64];                                                       \
         for (ch = 0; ch < nb_channels; ch++) {                              \
             snprintf(key, sizeof(key),                                      \
                      META_PREFIX AV_STRINGIFY(name) "_peaks_ch%d", ch);     \
             SET_META(key, ebur128->name##_peaks[ch]);                       \
         }                                                                   \
     }                                                                       \
 } while (0)
 
                 SET_META(META_PREFIX "M",        loudness_400);
                 SET_META(META_PREFIX "S",        loudness_3000);
                 SET_META(META_PREFIX "I",        ebur128->integrated_loudness);
                 SET_META(META_PREFIX "LRA",      ebur128->loudness_range);
                 SET_META(META_PREFIX "LRA.low",  ebur128->lra_low);
                 SET_META(META_PREFIX "LRA.high", ebur128->lra_high);
 
                 SET_META_PEAK(sample, SAMPLES);
                 SET_META_PEAK(true,   TRUE);

             }
 

             av_log(ctx, ebur128->loglevel, "t: %-10s " LOG_FMT,

                    av_ts2timestr(pts, &outlink->time_base),

                    loudness_400, loudness_3000,
                    ebur128->integrated_loudness, ebur128->loudness_range);

 #define PRINT_PEAKS(str, sp, ptype) do {                            \
     if (ebur128->peak_mode & PEAK_MODE_ ## ptype ## _PEAKS) {       \
         av_log(ctx, ebur128->loglevel, "  " str ":");               \
         for (ch = 0; ch < nb_channels; ch++)                        \
             av_log(ctx, ebur128->loglevel, " %5.1f", DBFS(sp[ch])); \
         av_log(ctx, ebur128->loglevel, " dBFS");                    \
     }                                                               \

 } while (0)
 
             PRINT_PEAKS("SPK", ebur128->sample_peaks, SAMPLES);

             PRINT_PEAKS("FTPK", ebur128->true_peaks_per_frame, TRUE);

             PRINT_PEAKS("TPK", ebur128->true_peaks,   TRUE);
             av_log(ctx, ebur128->loglevel, "\n");

         }
     }
 

     return ff_filter_frame(ctx->outputs[ebur128->do_video], insamples);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     EBUR128Context *ebur128 = ctx->priv;
     AVFilterFormats *formats;
     AVFilterChannelLayouts *layouts;
     AVFilterLink *inlink = ctx->inputs[0];
     AVFilterLink *outlink = ctx->outputs[0];

     int ret;

     static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_NONE };

     static const int input_srate[] = {48000, -1}; // ITU-R BS.1770 provides coeff only for 48kHz

     static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_RGB24, AV_PIX_FMT_NONE };

 
     /* set optional output video format */
     if (ebur128->do_video) {
         formats = ff_make_format_list(pix_fmts);

         if ((ret = ff_formats_ref(formats, &outlink->in_formats)) < 0)
             return ret;

         outlink = ctx->outputs[1];
     }
 

     /* set input and output audio formats
      * Note: ff_set_common_* functions are not used because they affect all the

      * links, and thus break the video format negotiation */

     formats = ff_make_format_list(sample_fmts);

     if ((ret = ff_formats_ref(formats, &inlink->out_formats)) < 0 ||
         (ret = ff_formats_ref(formats, &outlink->in_formats)) < 0)
         return ret;

 
     layouts = ff_all_channel_layouts();

     if ((ret = ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts)) < 0 ||
         (ret = ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts)) < 0)
         return ret;

 
     formats = ff_make_format_list(input_srate);

     if ((ret = ff_formats_ref(formats, &inlink->out_samplerates)) < 0 ||
         (ret = ff_formats_ref(formats, &outlink->in_samplerates)) < 0)
         return ret;

     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     int i;
     EBUR128Context *ebur128 = ctx->priv;
 

     /* dual-mono correction */
     if (ebur128->nb_channels == 1 && ebur128->dual_mono) {
         ebur128->i400.rel_threshold -= ebur128->pan_law;
         ebur128->i3000.rel_threshold -= ebur128->pan_law;
         ebur128->lra_low -= ebur128->pan_law;
         ebur128->lra_high -= ebur128->pan_law;
     }
 

     av_log(ctx, AV_LOG_INFO, "Summary:\n\n"
            "  Integrated loudness:\n"
            "    I:         %5.1f LUFS\n"
            "    Threshold: %5.1f LUFS\n\n"
            "  Loudness range:\n"
            "    LRA:       %5.1f LU\n"
            "    Threshold: %5.1f LUFS\n"
            "    LRA low:   %5.1f LUFS\n"

            "    LRA high:  %5.1f LUFS",

            ebur128->integrated_loudness, ebur128->i400.rel_threshold,
            ebur128->loudness_range,      ebur128->i3000.rel_threshold,
            ebur128->lra_low, ebur128->lra_high);
 

 #define PRINT_PEAK_SUMMARY(str, sp, ptype) do {                  \
     int ch;                                                      \
     double maxpeak;                                              \
     maxpeak = 0.0;                                               \
     if (ebur128->peak_mode & PEAK_MODE_ ## ptype ## _PEAKS) {    \
         for (ch = 0; ch < ebur128->nb_channels; ch++)            \
             maxpeak = FFMAX(maxpeak, sp[ch]);                    \
         av_log(ctx, AV_LOG_INFO, "\n\n  " str " peak:\n"         \
                "    Peak:      %5.1f dBFS",                      \
                DBFS(maxpeak));                                   \
     }                                                            \
 } while (0)
 
     PRINT_PEAK_SUMMARY("Sample", ebur128->sample_peaks, SAMPLES);
     PRINT_PEAK_SUMMARY("True",   ebur128->true_peaks,   TRUE);
     av_log(ctx, AV_LOG_INFO, "\n");
 

     av_freep(&ebur128->y_line_ref);
     av_freep(&ebur128->ch_weighting);

     av_freep(&ebur128->true_peaks);
     av_freep(&ebur128->sample_peaks);

     av_freep(&ebur128->true_peaks_per_frame);

     av_freep(&ebur128->i400.histogram);
     av_freep(&ebur128->i3000.histogram);
     for (i = 0; i < ebur128->nb_channels; i++) {
         av_freep(&ebur128->i400.cache[i]);
         av_freep(&ebur128->i3000.cache[i]);
     }
     for (i = 0; i < ctx->nb_outputs; i++)
         av_freep(&ctx->output_pads[i].name);

     av_frame_free(&ebur128->outpicref);

 #if CONFIG_SWRESAMPLE
     av_freep(&ebur128->swr_buf);
     swr_free(&ebur128->swr_ctx);
 #endif

 }
 

 static const AVFilterPad ebur128_inputs[] = {
     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .filter_frame = filter_frame,
         .config_props = config_audio_input,

     },
     { NULL }
 };
 

 AVFilter ff_af_ebur128 = {

     .name          = "ebur128",
     .description   = NULL_IF_CONFIG_SMALL("EBU R128 scanner."),
     .priv_size     = sizeof(EBUR128Context),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,

     .inputs        = ebur128_inputs,
     .outputs       = NULL,

     .priv_class    = &ebur128_class,

     .flags         = AVFILTER_FLAG_DYNAMIC_OUTPUTS,

 };