/*
  * Copyright (c) 2010 Nolan Lum <nol888@gmail.com>
  * Copyright (c) 2009 Loren Merritt <lorenm@u.washignton.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).
  * Foreach pixel, if it's within 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/cpu.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "gradfun.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; x++, dc += x & 1) {
         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;
     }
 }
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     GradFunContext *gf = ctx->priv;
     float thresh = 1.2;
     int radius = 16;
     av_unused int cpu_flags = av_get_cpu_flags();
 
     if (args)
         sscanf(args, "%f:%d", &thresh, &radius);
 
     thresh = av_clipf(thresh, 0.51, 255);
     gf->thresh = (1 << 15) / thresh;
     gf->radius = av_clip((radius + 1) & ~1, 4, 32);
 
     gf->blur_line = ff_gradfun_blur_line_c;
     gf->filter_line = ff_gradfun_filter_line_c;
 
     if (HAVE_MMX && cpu_flags & AV_CPU_FLAG_MMX2)
         gf->filter_line = ff_gradfun_filter_line_mmx2;
     if (HAVE_SSSE3 && cpu_flags & AV_CPU_FLAG_SSSE3)
         gf->filter_line = ff_gradfun_filter_line_ssse3;
     if (HAVE_SSE && cpu_flags & AV_CPU_FLAG_SSE2)
         gf->blur_line = ff_gradfun_blur_line_sse2;
 
     av_log(ctx, AV_LOG_INFO, "threshold:%.2f radius:%d\n", thresh, gf->radius);
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     GradFunContext *gf = ctx->priv;
     av_freep(&gf->buf);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum PixelFormat pix_fmts[] = {
         PIX_FMT_YUV410P,            PIX_FMT_YUV420P,
         PIX_FMT_GRAY8,              PIX_FMT_NV12,
         PIX_FMT_NV21,               PIX_FMT_YUV444P,
         PIX_FMT_YUV422P,            PIX_FMT_YUV411P,
         PIX_FMT_NONE
     };
 

     avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));

 
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     GradFunContext *gf = inlink->dst->priv;
     int hsub = av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
     int vsub = av_pix_fmt_descriptors[inlink->format].log2_chroma_h;
 
     gf->buf = av_mallocz((FFALIGN(inlink->w, 16) * (gf->radius + 1) / 2 + 32) * sizeof(uint16_t));
     if (!gf->buf)
         return AVERROR(ENOMEM);
 
     gf->chroma_w = -((-inlink->w) >> hsub);
     gf->chroma_h = -((-inlink->h) >> vsub);
     gf->chroma_r = av_clip(((((gf->radius >> hsub) + (gf->radius >> vsub)) / 2 ) + 1) & ~1, 4, 32);
 
     return 0;
 }
 
 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
 {
     AVFilterLink *outlink = inlink->dst->outputs[0];
     AVFilterBufferRef *outpicref;
 
     if (inpicref->perms & AV_PERM_PRESERVE) {
         outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
         avfilter_copy_buffer_ref_props(outpicref, inpicref);
         outpicref->video->w = outlink->w;
         outpicref->video->h = outlink->h;
     } else
         outpicref = inpicref;
 
     outlink->out_buf = outpicref;
     avfilter_start_frame(outlink, avfilter_ref_buffer(outpicref, ~0));
 }
 
 static void null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { }
 
 static void end_frame(AVFilterLink *inlink)
 {
     GradFunContext *gf = inlink->dst->priv;
     AVFilterBufferRef *inpic = inlink->cur_buf;
     AVFilterLink *outlink = inlink->dst->outputs[0];
     AVFilterBufferRef *outpic = outlink->out_buf;
     int p;
 
     for (p = 0; p < 4 && inpic->data[p]; p++) {
         int w = inlink->w;
         int h = inlink->h;
         int r = gf->radius;
         if (p) {
             w = gf->chroma_w;
             h = gf->chroma_h;
             r = gf->chroma_r;
         }
 
         if (FFMIN(w, h) > 2 * r)
             filter(gf, outpic->data[p], inpic->data[p], w, h, outpic->linesize[p], inpic->linesize[p], r);
         else if (outpic->data[p] != inpic->data[p])
             av_image_copy_plane(outpic->data[p], outpic->linesize[p], inpic->data[p], inpic->linesize[p], w, h);
     }
 
     avfilter_draw_slice(outlink, 0, inlink->h, 1);
     avfilter_end_frame(outlink);
     avfilter_unref_buffer(inpic);

     if (outpic != inpic)
         avfilter_unref_buffer(outpic);

 }
 
 AVFilter avfilter_vf_gradfun = {
     .name          = "gradfun",
     .description   = NULL_IF_CONFIG_SMALL("Debands video quickly using gradients."),
     .priv_size     = sizeof(GradFunContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
 

     .inputs    = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,
                                     .config_props     = config_input,
                                     .start_frame      = start_frame,
                                     .draw_slice       = null_draw_slice,
                                     .end_frame        = end_frame,
                                     .min_perms        = AV_PERM_READ, },
                                   { .name = NULL}},

     .outputs   = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO, },
                                   { .name = NULL}},
 };