/*
  * Copyright (c) 2010 Nolan Lum <nol888@gmail.com>

  * Copyright (c) 2009 Loren Merritt <lorenm@u.washington.edu>

  *
  * 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
  * gradfun debanding filter, ported from MPlayer
  * libmpcodecs/vf_gradfun.c
  *
  * Apply a boxblur debanding algorithm (based on the gradfun2db

  * AviSynth filter by prunedtree).

  * For each pixel, if it is within the threshold of the blurred value, make it
  * closer. So now we have a smoothed and higher bitdepth version of all the
  * shallow gradients, while leaving detailed areas untouched.

  * Dither it back to 8bit.
  */
 

 #include "libavutil/imgutils.h"

 #include "libavutil/common.h"

 #include "libavutil/cpu.h"

 #include "libavutil/opt.h"

 #include "libavutil/pixdesc.h"
 #include "avfilter.h"

 #include "formats.h"

 #include "gradfun.h"

 #include "internal.h"

 #include "video.h"

 
 DECLARE_ALIGNED(16, static const uint16_t, dither)[8][8] = {
     {0x00,0x60,0x18,0x78,0x06,0x66,0x1E,0x7E},
     {0x40,0x20,0x58,0x38,0x46,0x26,0x5E,0x3E},
     {0x10,0x70,0x08,0x68,0x16,0x76,0x0E,0x6E},
     {0x50,0x30,0x48,0x28,0x56,0x36,0x4E,0x2E},
     {0x04,0x64,0x1C,0x7C,0x02,0x62,0x1A,0x7A},
     {0x44,0x24,0x5C,0x3C,0x42,0x22,0x5A,0x3A},
     {0x14,0x74,0x0C,0x6C,0x12,0x72,0x0A,0x6A},
     {0x54,0x34,0x4C,0x2C,0x52,0x32,0x4A,0x2A},
 };
 

 void ff_gradfun_filter_line_c(uint8_t *dst, const uint8_t *src, const uint16_t *dc, int width, int thresh, const uint16_t *dithers)

 {
     int x;

     for (x = 0; x < width; dc += x & 1, x++) {

         int pix = src[x] << 7;
         int delta = dc[0] - pix;
         int m = abs(delta) * thresh >> 16;
         m = FFMAX(0, 127 - m);
         m = m * m * delta >> 14;
         pix += m + dithers[x & 7];
         dst[x] = av_clip_uint8(pix >> 7);
     }
 }
 

 void ff_gradfun_blur_line_c(uint16_t *dc, uint16_t *buf, const uint16_t *buf1, const uint8_t *src, int src_linesize, int width)

 {
     int x, v, old;
     for (x = 0; x < width; x++) {
         v = buf1[x] + src[2 * x] + src[2 * x + 1] + src[2 * x + src_linesize] + src[2 * x + 1 + src_linesize];
         old = buf[x];
         buf[x] = v;
         dc[x] = v - old;
     }
 }
 

 static void filter(GradFunContext *ctx, uint8_t *dst, const uint8_t *src, int width, int height, int dst_linesize, int src_linesize, int r)

 {
     int bstride = FFALIGN(width, 16) / 2;
     int y;
     uint32_t dc_factor = (1 << 21) / (r * r);
     uint16_t *dc = ctx->buf + 16;
     uint16_t *buf = ctx->buf + bstride + 32;
     int thresh = ctx->thresh;
 
     memset(dc, 0, (bstride + 16) * sizeof(*buf));
     for (y = 0; y < r; y++)
         ctx->blur_line(dc, buf + y * bstride, buf + (y - 1) * bstride, src + 2 * y * src_linesize, src_linesize, width / 2);
     for (;;) {
         if (y < height - r) {
             int mod = ((y + r) / 2) % r;
             uint16_t *buf0 = buf + mod * bstride;
             uint16_t *buf1 = buf + (mod ? mod - 1 : r - 1) * bstride;
             int x, v;
             ctx->blur_line(dc, buf0, buf1, src + (y + r) * src_linesize, src_linesize, width / 2);
             for (x = v = 0; x < r; x++)
                 v += dc[x];
             for (; x < width / 2; x++) {
                 v += dc[x] - dc[x-r];
                 dc[x-r] = v * dc_factor >> 16;
             }
             for (; x < (width + r + 1) / 2; x++)
                 dc[x-r] = v * dc_factor >> 16;
             for (x = -r / 2; x < 0; x++)
                 dc[x] = dc[0];
         }
         if (y == r) {
             for (y = 0; y < r; y++)
                 ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
         }
         ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
         if (++y >= height) break;
         ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
         if (++y >= height) break;
     }

     emms_c();

 }
 

 static av_cold int init(AVFilterContext *ctx)

 {

     GradFunContext *s = ctx->priv;

     s->thresh  = (1 << 15) / s->strength;

     s->radius  = av_clip((s->radius + 1) & ~1, 4, 32);

     s->blur_line   = ff_gradfun_blur_line_c;

     s->filter_line = ff_gradfun_filter_line_c;

     if (ARCH_X86)

         ff_gradfun_init_x86(s);

     av_log(ctx, AV_LOG_VERBOSE, "threshold:%.2f radius:%d\n", s->strength, s->radius);

 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {

     GradFunContext *s = ctx->priv;
     av_freep(&s->buf);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV410P,            AV_PIX_FMT_YUV420P,

         AV_PIX_FMT_GRAY8,              AV_PIX_FMT_YUV444P,

         AV_PIX_FMT_YUV422P,            AV_PIX_FMT_YUV411P,

         AV_PIX_FMT_YUV440P,

         AV_PIX_FMT_GBRP,

         AV_PIX_FMT_NONE

     };

     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);

 }
 
 static int config_input(AVFilterLink *inlink)
 {

     GradFunContext *s = inlink->dst->priv;

     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int hsub = desc->log2_chroma_w;
     int vsub = desc->log2_chroma_h;

     av_freep(&s->buf);

     s->buf = av_calloc((FFALIGN(inlink->w, 16) * (s->radius + 1) / 2 + 32), sizeof(*s->buf));

     if (!s->buf)

         return AVERROR(ENOMEM);
 

     s->chroma_w = AV_CEIL_RSHIFT(inlink->w, hsub);
     s->chroma_h = AV_CEIL_RSHIFT(inlink->h, vsub);

     s->chroma_r = av_clip(((((s->radius >> hsub) + (s->radius >> vsub)) / 2 ) + 1) & ~1, 4, 32);

 
     return 0;
 }
 

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

 {

     GradFunContext *s = inlink->dst->priv;

     AVFilterLink *outlink = inlink->dst->outputs[0];

     AVFrame *out;

     int p, direct;

     if (av_frame_is_writable(in)) {

         direct = 1;
         out = in;
     } else {

         direct = 0;

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

         if (!out) {

             av_frame_free(&in);

             return AVERROR(ENOMEM);
         }

         av_frame_copy_props(out, in);

     }

     for (p = 0; p < 4 && in->data[p] && in->linesize[p]; p++) {

         int w = inlink->w;
         int h = inlink->h;

         int r = s->radius;

         if (p) {

             w = s->chroma_w;
             h = s->chroma_h;
             r = s->chroma_r;

         }
 
         if (FFMIN(w, h) > 2 * r)

             filter(s, out->data[p], in->data[p], w, h, out->linesize[p], in->linesize[p], r);

         else if (out->data[p] != in->data[p])
             av_image_copy_plane(out->data[p], out->linesize[p], in->data[p], in->linesize[p], w, h);

     }
 

     if (!direct)

         av_frame_free(&in);

 
     return ff_filter_frame(outlink, out);

 }
 

 #define OFFSET(x) offsetof(GradFunContext, x)

 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption gradfun_options[] = {

     { "strength", "The maximum amount by which the filter will change any one pixel.", OFFSET(strength), AV_OPT_TYPE_FLOAT, { .dbl = 1.2 }, 0.51, 64, FLAGS },
     { "radius",   "The neighborhood to fit the gradient to.",                          OFFSET(radius),   AV_OPT_TYPE_INT,   { .i64 = 16  }, 4,    32, FLAGS },

     { NULL }

 };
 

 AVFILTER_DEFINE_CLASS(gradfun);

 static const AVFilterPad avfilter_vf_gradfun_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input,

         .filter_frame = filter_frame,

     },
     { NULL }
 };
 
 static const AVFilterPad avfilter_vf_gradfun_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 

 AVFilter ff_vf_gradfun = {

     .name          = "gradfun",
     .description   = NULL_IF_CONFIG_SMALL("Debands video quickly using gradients."),
     .priv_size     = sizeof(GradFunContext),

     .priv_class    = &gradfun_class,

     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,

     .inputs        = avfilter_vf_gradfun_inputs,
     .outputs       = avfilter_vf_gradfun_outputs,

     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

 };