/*
  * Copyright (C) 2001-2010 Krzysztof Foltman, Markus Schmidt, Thor Harald Johansen
  *
  * 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
  */
 
 #include "libavutil/channel_layout.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "audio.h"
 #include "formats.h"
 
 typedef struct StereoToolsContext {
     const AVClass *class;
 
     int softclip;
     int mute_l;
     int mute_r;
     int phase_l;
     int phase_r;
     int mode;

     int bmode_in;
     int bmode_out;

     double slev;
     double sbal;
     double mlev;
     double mpan;
     double phase;
     double base;
     double delay;
     double balance_in;
     double balance_out;
     double phase_sin_coef;
     double phase_cos_coef;
     double sc_level;
     double inv_atan_shape;
     double level_in;
     double level_out;
 
     double *buffer;
     int length;
     int pos;
 } StereoToolsContext;
 
 #define OFFSET(x) offsetof(StereoToolsContext, x)
 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption stereotools_options[] = {
     { "level_in",    "set level in",     OFFSET(level_in),    AV_OPT_TYPE_DOUBLE, {.dbl=1},   0.015625,  64, A },
     { "level_out",   "set level out",    OFFSET(level_out),   AV_OPT_TYPE_DOUBLE, {.dbl=1},   0.015625,  64, A },
     { "balance_in",  "set balance in",   OFFSET(balance_in),  AV_OPT_TYPE_DOUBLE, {.dbl=0},  -1,          1, A },
     { "balance_out", "set balance out",  OFFSET(balance_out), AV_OPT_TYPE_DOUBLE, {.dbl=0},  -1,          1, A },
     { "softclip",    "enable softclip",  OFFSET(softclip),    AV_OPT_TYPE_BOOL,   {.i64=0},   0,          1, A },
     { "mutel",       "mute L",           OFFSET(mute_l),      AV_OPT_TYPE_BOOL,   {.i64=0},   0,          1, A },
     { "muter",       "mute R",           OFFSET(mute_r),      AV_OPT_TYPE_BOOL,   {.i64=0},   0,          1, A },
     { "phasel",      "phase L",          OFFSET(phase_l),     AV_OPT_TYPE_BOOL,   {.i64=0},   0,          1, A },
     { "phaser",      "phase R",          OFFSET(phase_r),     AV_OPT_TYPE_BOOL,   {.i64=0},   0,          1, A },

     { "mode",        "set stereo mode",  OFFSET(mode),        AV_OPT_TYPE_INT,    {.i64=0},   0,          8, A, "mode" },

     {     "lr>lr",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=0},   0,          0, A, "mode" },
     {     "lr>ms",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=1},   0,          0, A, "mode" },
     {     "ms>lr",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=2},   0,          0, A, "mode" },
     {     "lr>ll",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=3},   0,          0, A, "mode" },
     {     "lr>rr",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=4},   0,          0, A, "mode" },
     {     "lr>l+r",  0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=5},   0,          0, A, "mode" },
     {     "lr>rl",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=6},   0,          0, A, "mode" },

     {     "ms>ll",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=7},   0,          0, A, "mode" },
     {     "ms>rr",   0,                  0,                   AV_OPT_TYPE_CONST,  {.i64=8},   0,          0, A, "mode" },

     { "slev",        "set side level",   OFFSET(slev),        AV_OPT_TYPE_DOUBLE, {.dbl=1},   0.015625,  64, A },
     { "sbal",        "set side balance", OFFSET(sbal),        AV_OPT_TYPE_DOUBLE, {.dbl=0},  -1,          1, A },
     { "mlev",        "set middle level", OFFSET(mlev),        AV_OPT_TYPE_DOUBLE, {.dbl=1},   0.015625,  64, A },
     { "mpan",        "set middle pan",   OFFSET(mpan),        AV_OPT_TYPE_DOUBLE, {.dbl=0},  -1,          1, A },
     { "base",        "set stereo base",  OFFSET(base),        AV_OPT_TYPE_DOUBLE, {.dbl=0},  -1,          1, A },
     { "delay",       "set delay",        OFFSET(delay),       AV_OPT_TYPE_DOUBLE, {.dbl=0}, -20,         20, A },
     { "sclevel",     "set S/C level",    OFFSET(sc_level),    AV_OPT_TYPE_DOUBLE, {.dbl=1},   1,        100, A },
     { "phase",       "set stereo phase", OFFSET(phase),       AV_OPT_TYPE_DOUBLE, {.dbl=0},   0,        360, A },

     { "bmode_in",    "set balance in mode", OFFSET(bmode_in), AV_OPT_TYPE_INT,    {.i64=0},   0,          2, A, "bmode" },
     {     "balance",   0,                0,                   AV_OPT_TYPE_CONST,  {.i64=0},   0,          0, A, "bmode" },
     {     "amplitude", 0,                0,                   AV_OPT_TYPE_CONST,  {.i64=1},   0,          0, A, "bmode" },
     {     "power",     0,                0,                   AV_OPT_TYPE_CONST,  {.i64=2},   0,          0, A, "bmode" },
     { "bmode_out", "set balance out mode", OFFSET(bmode_out), AV_OPT_TYPE_INT,    {.i64=0},   0,          2, A, "bmode" },

     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(stereotools);
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats = NULL;
     AVFilterChannelLayouts *layout = NULL;

     int ret;

     if ((ret = ff_add_format                 (&formats, AV_SAMPLE_FMT_DBL  )) < 0 ||
         (ret = ff_set_common_formats         (ctx     , formats            )) < 0 ||
         (ret = ff_add_channel_layout         (&layout , AV_CH_LAYOUT_STEREO)) < 0 ||
         (ret = ff_set_common_channel_layouts (ctx     , layout             )) < 0)
         return ret;

 
     formats = ff_all_samplerates();
     return ff_set_common_samplerates(ctx, formats);
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     StereoToolsContext *s = ctx->priv;
 
     s->length = 2 * inlink->sample_rate * 0.05;

     if (s->length <= 1 || s->length & 1) {

         av_log(ctx, AV_LOG_ERROR, "sample rate is too small\n");
         return AVERROR(EINVAL);
     }

     s->buffer = av_calloc(s->length, sizeof(*s->buffer));
     if (!s->buffer)
         return AVERROR(ENOMEM);
 
     s->inv_atan_shape = 1.0 / atan(s->sc_level);
     s->phase_cos_coef = cos(s->phase / 180 * M_PI);
     s->phase_sin_coef = sin(s->phase / 180 * M_PI);
 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     StereoToolsContext *s = ctx->priv;
     const double *src = (const double *)in->data[0];
     const double sb = s->base < 0 ? s->base * 0.5 : s->base;
     const double sbal = 1 + s->sbal;
     const double mpan = 1 + s->mpan;
     const double slev = s->slev;
     const double mlev = s->mlev;
     const double balance_in = s->balance_in;
     const double balance_out = s->balance_out;
     const double level_in = s->level_in;
     const double level_out = s->level_out;
     const double sc_level = s->sc_level;
     const double delay = s->delay;
     const int length = s->length;

     const int mute_l = s->mute_l;
     const int mute_r = s->mute_r;
     const int phase_l = s->phase_l;
     const int phase_r = s->phase_r;

     double *buffer = s->buffer;

     AVFrame *out;

     double *dst;

     int nbuf = inlink->sample_rate * (fabs(delay) / 1000.);

     int n;
 
     nbuf -= nbuf % 2;
     if (av_frame_is_writable(in)) {
         out = in;
     } else {

         out = ff_get_audio_buffer(inlink, in->nb_samples);

         if (!out) {
             av_frame_free(&in);
             return AVERROR(ENOMEM);
         }
         av_frame_copy_props(out, in);
     }
     dst = (double *)out->data[0];
 
     for (n = 0; n < in->nb_samples; n++, src += 2, dst += 2) {

         double L = src[0], R = src[1], l, r, m, S, gl, gr, gd;

 
         L *= level_in;
         R *= level_in;
 

         gl = 1. - FFMAX(0., balance_in);
         gr = 1. + FFMIN(0., balance_in);
         switch (s->bmode_in) {
         case 1:
             gd = gl - gr;
             gl = 1. + gd;
             gr = 1. - gd;
             break;
         case 2:
             if (balance_in < 0.) {
                 gr = FFMAX(0.5, gr);
                 gl = 1. / gr;
             } else if (balance_in > 0.) {
                 gl = FFMAX(0.5, gl);
                 gr = 1. / gl;
             }
             break;
         }
         L *= gl;
         R *= gr;

 
         if (s->softclip) {
             R = s->inv_atan_shape * atan(R * sc_level);
             L = s->inv_atan_shape * atan(L * sc_level);
         }
 
         switch (s->mode) {
         case 0:
             m = (L + R) * 0.5;
             S = (L - R) * 0.5;
             l = m * mlev * FFMIN(1., 2. - mpan) + S * slev * FFMIN(1., 2. - sbal);
             r = m * mlev * FFMIN(1., mpan)      - S * slev * FFMIN(1., sbal);
             L = l;
             R = r;
             break;
         case 1:
             l = L * FFMIN(1., 2. - sbal);
             r = R * FFMIN(1., sbal);
             L = 0.5 * (l + r) * mlev;
             R = 0.5 * (l - r) * slev;
             break;
         case 2:
             l = L * mlev * FFMIN(1., 2. - mpan) + R * slev * FFMIN(1., 2. - sbal);
             r = L * mlev * FFMIN(1., mpan)      - R * slev * FFMIN(1., sbal);
             L = l;
             R = r;
             break;
         case 3:
             R = L;
             break;
         case 4:
             L = R;
             break;
         case 5:
             L = (L + R) / 2;
             R = L;
             break;
         case 6:
             l = L;
             L = R;
             R = l;
             m = (L + R) * 0.5;
             S = (L - R) * 0.5;
             l = m * mlev * FFMIN(1., 2. - mpan) + S * slev * FFMIN(1., 2. - sbal);
             r = m * mlev * FFMIN(1., mpan)      - S * slev * FFMIN(1., sbal);
             L = l;
             R = r;

             break;

         case 7:
             l = L * mlev * FFMIN(1., 2. - mpan) + R * slev * FFMIN(1., 2. - sbal);
             L = l;
             R = l;
             break;
         case 8:
             r = L * mlev * FFMIN(1., mpan)      - R * slev * FFMIN(1., sbal);
             L = r;
             R = r;

             break;
         }
 
         L *= 1. - mute_l;
         R *= 1. - mute_r;
 
         L *= (2. * (1. - phase_l)) - 1.;
         R *= (2. * (1. - phase_r)) - 1.;
 
         buffer[s->pos  ] = L;
         buffer[s->pos+1] = R;
 
         if (delay > 0.) {
             R = buffer[(s->pos - (int)nbuf + 1 + length) % length];
         } else if (delay < 0.) {
             L = buffer[(s->pos - (int)nbuf + length)     % length];
         }
 
         l = L + sb * L - sb * R;
         r = R + sb * R - sb * L;
 
         L = l;
         R = r;
 
         l = L * s->phase_cos_coef - R * s->phase_sin_coef;
         r = L * s->phase_sin_coef + R * s->phase_cos_coef;
 
         L = l;
         R = r;
 
         s->pos = (s->pos + 2) % s->length;
 

         gl = 1. - FFMAX(0., balance_out);
         gr = 1. + FFMIN(0., balance_out);
         switch (s->bmode_out) {
         case 1:
             gd = gl - gr;
             gl = 1. + gd;
             gr = 1. - gd;
             break;
         case 2:
             if (balance_out < 0.) {
                 gr = FFMAX(0.5, gr);
                 gl = 1. / gr;
             } else if (balance_out > 0.) {
                 gl = FFMAX(0.5, gl);
                 gr = 1. / gl;
             }
             break;
         }
         L *= gl;
         R *= gr;
 

 
         L *= level_out;
         R *= level_out;
 
         dst[0] = L;
         dst[1] = R;
     }
 
     if (out != in)
         av_frame_free(&in);
     return ff_filter_frame(outlink, out);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     StereoToolsContext *s = ctx->priv;
 
     av_freep(&s->buffer);
 }
 
 static const AVFilterPad inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     },
     { NULL }
 };
 
 static const AVFilterPad outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_AUDIO,
     },
     { NULL }
 };
 
 AVFilter ff_af_stereotools = {
     .name           = "stereotools",
     .description    = NULL_IF_CONFIG_SMALL("Apply various stereo tools."),
     .query_formats  = query_formats,
     .priv_size      = sizeof(StereoToolsContext),
     .priv_class     = &stereotools_class,
     .uninit         = uninit,
     .inputs         = inputs,
     .outputs        = outputs,
 };