/*
  * 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
  * audio to spectrum (video) transmedia filter, based on ffplay rdft showmode
  * (by Michael Niedermayer) and lavfi/avf_showwaves (by Stefano Sabatini).
  */
 
 #include <math.h>
 
 #include "libavcodec/avfft.h"

 #include "libavutil/channel_layout.h"

 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "internal.h"
 
 typedef struct {
     const AVClass *class;
     int w, h;
     AVFilterBufferRef *outpicref;
     int req_fullfilled;

     int sliding;                ///< 1 if sliding mode, 0 otherwise

     int xpos;                   ///< x position (current column)
     RDFTContext *rdft;          ///< Real Discrete Fourier Transform context
     int rdft_bits;              ///< number of bits (RDFT window size = 1<<rdft_bits)
     FFTSample *rdft_data;       ///< bins holder for each (displayed) channels
     int filled;                 ///< number of samples (per channel) filled in current rdft_buffer
     int consumed;               ///< number of samples (per channel) consumed from the input frame
     float *window_func_lut;     ///< Window function LUT
 } ShowSpectrumContext;
 
 #define OFFSET(x) offsetof(ShowSpectrumContext, x)

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

 
 static const AVOption showspectrum_options[] = {

     { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, FLAGS },
     { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, FLAGS },

     { "slide", "set sliding mode", OFFSET(sliding), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },

     { NULL },
 };
 
 AVFILTER_DEFINE_CLASS(showspectrum);
 
 static av_cold int init(AVFilterContext *ctx, const char *args)
 {
     ShowSpectrumContext *showspectrum = ctx->priv;
     int err;
 
     showspectrum->class = &showspectrum_class;
     av_opt_set_defaults(showspectrum);
 
     if ((err = av_set_options_string(showspectrum, args, "=", ":")) < 0)
         return err;
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     ShowSpectrumContext *showspectrum = ctx->priv;
 
     av_rdft_end(showspectrum->rdft);
     av_freep(&showspectrum->rdft_data);
     av_freep(&showspectrum->window_func_lut);
     avfilter_unref_bufferp(&showspectrum->outpicref);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats = NULL;
     AVFilterChannelLayouts *layouts = NULL;
     AVFilterLink *inlink = ctx->inputs[0];
     AVFilterLink *outlink = ctx->outputs[0];

     static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16P, AV_SAMPLE_FMT_NONE };
     static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_RGB24, AV_PIX_FMT_NONE };

 
     /* set input audio formats */
     formats = ff_make_format_list(sample_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ff_formats_ref(formats, &inlink->out_formats);
 
     layouts = ff_all_channel_layouts();
     if (!layouts)
         return AVERROR(ENOMEM);
     ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
 
     formats = ff_all_samplerates();
     if (!formats)
         return AVERROR(ENOMEM);
     ff_formats_ref(formats, &inlink->out_samplerates);
 
     /* set output video format */
     formats = ff_make_format_list(pix_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ff_formats_ref(formats, &outlink->in_formats);
 
     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     ShowSpectrumContext *showspectrum = ctx->priv;
     int i, rdft_bits, win_size;
 
     outlink->w = showspectrum->w;
     outlink->h = showspectrum->h;
 
     /* RDFT window size (precision) according to the requested output frame height */
     for (rdft_bits = 1; 1<<rdft_bits < 2*outlink->h; rdft_bits++);
     win_size = 1 << rdft_bits;
 
     /* (re-)configuration if the video output changed (or first init) */
     if (rdft_bits != showspectrum->rdft_bits) {

         size_t rdft_size;

         AVFilterBufferRef *outpicref;
 
         av_rdft_end(showspectrum->rdft);
         showspectrum->rdft = av_rdft_init(rdft_bits, DFT_R2C);
         showspectrum->rdft_bits = rdft_bits;
 

         /* RDFT buffers: x2 for each (display) channel buffer.
          * Note: we use free and malloc instead of a realloc-like function to
          * make sure the buffer is aligned in memory for the FFT functions. */
         av_freep(&showspectrum->rdft_data);
         if (av_size_mult(sizeof(*showspectrum->rdft_data), 2 * win_size, &rdft_size) < 0)
             return AVERROR(EINVAL);
         showspectrum->rdft_data = av_malloc(rdft_size);

         if (!showspectrum->rdft_data)
             return AVERROR(ENOMEM);
         showspectrum->filled = 0;
 
         /* pre-calc windowing function (hann here) */
         showspectrum->window_func_lut =
             av_realloc_f(showspectrum->window_func_lut, win_size,
                          sizeof(*showspectrum->window_func_lut));
         if (!showspectrum->window_func_lut)
             return AVERROR(ENOMEM);
         for (i = 0; i < win_size; i++)
             showspectrum->window_func_lut[i] = .5f * (1 - cos(2*M_PI*i / (win_size-1)));
 
         /* prepare the initial picref buffer (black frame) */
         avfilter_unref_bufferp(&showspectrum->outpicref);
         showspectrum->outpicref = outpicref =
             ff_get_video_buffer(outlink, AV_PERM_WRITE|AV_PERM_PRESERVE|AV_PERM_REUSE2,
                                 outlink->w, outlink->h);
         if (!outpicref)
             return AVERROR(ENOMEM);
         outlink->sample_aspect_ratio = (AVRational){1,1};
         memset(outpicref->data[0], 0, outlink->h * outpicref->linesize[0]);
     }
 
     if (showspectrum->xpos >= outlink->w)
         showspectrum->xpos = 0;
 
     av_log(ctx, AV_LOG_VERBOSE, "s:%dx%d RDFT window size:%d\n",
            showspectrum->w, showspectrum->h, win_size);
     return 0;
 }
 
 inline static void push_frame(AVFilterLink *outlink)
 {
     ShowSpectrumContext *showspectrum = outlink->src->priv;
 
     showspectrum->xpos++;
     if (showspectrum->xpos >= outlink->w)
         showspectrum->xpos = 0;
     showspectrum->filled = 0;
     showspectrum->req_fullfilled = 1;
 

     ff_filter_frame(outlink, avfilter_ref_buffer(showspectrum->outpicref, ~AV_PERM_WRITE));

 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     ShowSpectrumContext *showspectrum = outlink->src->priv;
     AVFilterLink *inlink = outlink->src->inputs[0];
     int ret;
 
     showspectrum->req_fullfilled = 0;
     do {
         ret = ff_request_frame(inlink);
     } while (!showspectrum->req_fullfilled && ret >= 0);
 
     if (ret == AVERROR_EOF && showspectrum->outpicref)
         push_frame(outlink);
     return ret;
 }
 
 static int plot_spectrum_column(AVFilterLink *inlink, AVFilterBufferRef *insamples, int nb_samples)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     ShowSpectrumContext *showspectrum = ctx->priv;
     AVFilterBufferRef *outpicref = showspectrum->outpicref;
     const int nb_channels = av_get_channel_layout_nb_channels(insamples->audio->channel_layout);
 
     /* nb_freq contains the power of two superior or equal to the output image
      * height (or half the RDFT window size) */
     const int nb_freq = 1 << (showspectrum->rdft_bits - 1);
     const int win_size = nb_freq << 1;
 
     int ch, n, y;
     FFTSample *data[2];
     const int nb_display_channels = FFMIN(nb_channels, 2);
     const int start = showspectrum->filled;
     const int add_samples = FFMIN(win_size - start, nb_samples);
 
     /* fill RDFT input with the number of samples available */
     for (ch = 0; ch < nb_display_channels; ch++) {
         const int16_t *p = (int16_t *)insamples->extended_data[ch];
 
         p += showspectrum->consumed;
         data[ch] = showspectrum->rdft_data + win_size * ch; // select channel buffer
         for (n = 0; n < add_samples; n++)
             data[ch][start + n] = p[n] * showspectrum->window_func_lut[start + n];
     }
     showspectrum->filled += add_samples;
 
     /* complete RDFT window size? */
     if (showspectrum->filled == win_size) {
 
         /* run RDFT on each samples set */
         for (ch = 0; ch < nb_display_channels; ch++)
             av_rdft_calc(showspectrum->rdft, data[ch]);
 
         /* fill a new spectrum column */
 #define RE(ch) data[ch][2*y + 0]
 #define IM(ch) data[ch][2*y + 1]
 #define MAGNITUDE(re, im) sqrt((re)*(re) + (im)*(im))
 
         for (y = 0; y < outlink->h; y++) {
             // FIXME: bin[0] contains first and last bins

             uint8_t *p = outpicref->data[0] + (outlink->h - y - 1) * outpicref->linesize[0];

             const double w = 1. / sqrt(nb_freq);
             int a =                           sqrt(w * MAGNITUDE(RE(0), IM(0)));
             int b = nb_display_channels > 1 ? sqrt(w * MAGNITUDE(RE(1), IM(1))) : a;
 

             if (showspectrum->sliding) {
                 memmove(p, p + 3, (outlink->w - 1) * 3);
                 p += (outlink->w - 1) * 3;
             } else {
                 p += showspectrum->xpos * 3;
             }
 

             a = FFMIN(a, 255);
             b = FFMIN(b, 255);

             p[0] = a;
             p[1] = b;
             p[2] = (a + b) / 2;

         }
         outpicref->pts = insamples->pts +
             av_rescale_q(showspectrum->consumed,
                          (AVRational){ 1, inlink->sample_rate },
                          outlink->time_base);
         push_frame(outlink);
     }
 
     return add_samples;
 }
 

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

 {
     AVFilterContext *ctx = inlink->dst;
     ShowSpectrumContext *showspectrum = ctx->priv;
     int left_samples = insamples->audio->nb_samples;
 
     showspectrum->consumed = 0;
     while (left_samples) {
         const int added_samples = plot_spectrum_column(inlink, insamples, left_samples);
         showspectrum->consumed += added_samples;
         left_samples -= added_samples;
     }
 
     avfilter_unref_buffer(insamples);
     return 0;
 }
 

 static const AVFilterPad showspectrum_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .filter_frame = filter_frame,
         .min_perms    = AV_PERM_READ,
     },
     { NULL }
 };
 
 static const AVFilterPad showspectrum_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
         .request_frame = request_frame,
     },
     { NULL }
 };
 

 AVFilter avfilter_avf_showspectrum = {
     .name           = "showspectrum",
     .description    = NULL_IF_CONFIG_SMALL("Convert input audio to a spectrum video output."),
     .init           = init,
     .uninit         = uninit,
     .query_formats  = query_formats,
     .priv_size      = sizeof(ShowSpectrumContext),

     .inputs         = showspectrum_inputs,
     .outputs        = showspectrum_outputs,
     .priv_class     = &showspectrum_class,

 };