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vf_gradfun.c
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1 /*
2  * Copyright (c) 2010 Nolan Lum <nol888@gmail.com>
3  * Copyright (c) 2009 Loren Merritt <lorenm@u.washington.edu>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * gradfun debanding filter, ported from MPlayer
25  * libmpcodecs/vf_gradfun.c
26  *
27  * Apply a boxblur debanding algorithm (based on the gradfun2db
28  * AviSynth filter by prunedtree).
29  * Foreach pixel, if it's within threshold of the blurred value, make it closer.
30  * So now we have a smoothed and higher bitdepth version of all the shallow
31  * gradients, while leaving detailed areas untouched.
32  * Dither it back to 8bit.
33  */
34 
35 #include "libavutil/imgutils.h"
36 #include "libavutil/common.h"
37 #include "libavutil/cpu.h"
38 #include "libavutil/opt.h"
39 #include "libavutil/pixdesc.h"
40 #include "avfilter.h"
41 #include "formats.h"
42 #include "gradfun.h"
43 #include "internal.h"
44 #include "video.h"
45 
46 DECLARE_ALIGNED(16, static const uint16_t, dither)[8][8] = {
47  {0x00,0x60,0x18,0x78,0x06,0x66,0x1E,0x7E},
48  {0x40,0x20,0x58,0x38,0x46,0x26,0x5E,0x3E},
49  {0x10,0x70,0x08,0x68,0x16,0x76,0x0E,0x6E},
50  {0x50,0x30,0x48,0x28,0x56,0x36,0x4E,0x2E},
51  {0x04,0x64,0x1C,0x7C,0x02,0x62,0x1A,0x7A},
52  {0x44,0x24,0x5C,0x3C,0x42,0x22,0x5A,0x3A},
53  {0x14,0x74,0x0C,0x6C,0x12,0x72,0x0A,0x6A},
54  {0x54,0x34,0x4C,0x2C,0x52,0x32,0x4A,0x2A},
55 };
56 
57 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)
58 {
59  int x;
60  for (x = 0; x < width; dc += x & 1, x++) {
61  int pix = src[x] << 7;
62  int delta = dc[0] - pix;
63  int m = abs(delta) * thresh >> 16;
64  m = FFMAX(0, 127 - m);
65  m = m * m * delta >> 14;
66  pix += m + dithers[x & 7];
67  dst[x] = av_clip_uint8(pix >> 7);
68  }
69 }
70 
71 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)
72 {
73  int x, v, old;
74  for (x = 0; x < width; x++) {
75  v = buf1[x] + src[2 * x] + src[2 * x + 1] + src[2 * x + src_linesize] + src[2 * x + 1 + src_linesize];
76  old = buf[x];
77  buf[x] = v;
78  dc[x] = v - old;
79  }
80 }
81 
82 static void filter(GradFunContext *ctx, uint8_t *dst, const uint8_t *src, int width, int height, int dst_linesize, int src_linesize, int r)
83 {
84  int bstride = FFALIGN(width, 16) / 2;
85  int y;
86  uint32_t dc_factor = (1 << 21) / (r * r);
87  uint16_t *dc = ctx->buf + 16;
88  uint16_t *buf = ctx->buf + bstride + 32;
89  int thresh = ctx->thresh;
90 
91  memset(dc, 0, (bstride + 16) * sizeof(*buf));
92  for (y = 0; y < r; y++)
93  ctx->blur_line(dc, buf + y * bstride, buf + (y - 1) * bstride, src + 2 * y * src_linesize, src_linesize, width / 2);
94  for (;;) {
95  if (y < height - r) {
96  int mod = ((y + r) / 2) % r;
97  uint16_t *buf0 = buf + mod * bstride;
98  uint16_t *buf1 = buf + (mod ? mod - 1 : r - 1) * bstride;
99  int x, v;
100  ctx->blur_line(dc, buf0, buf1, src + (y + r) * src_linesize, src_linesize, width / 2);
101  for (x = v = 0; x < r; x++)
102  v += dc[x];
103  for (; x < width / 2; x++) {
104  v += dc[x] - dc[x-r];
105  dc[x-r] = v * dc_factor >> 16;
106  }
107  for (; x < (width + r + 1) / 2; x++)
108  dc[x-r] = v * dc_factor >> 16;
109  for (x = -r / 2; x < 0; x++)
110  dc[x] = dc[0];
111  }
112  if (y == r) {
113  for (y = 0; y < r; y++)
114  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
115  }
116  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
117  if (++y >= height) break;
118  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
119  if (++y >= height) break;
120  }
121  emms_c();
122 }
123 
124 static av_cold int init(AVFilterContext *ctx)
125 {
126  GradFunContext *s = ctx->priv;
127 
128  s->thresh = (1 << 15) / s->strength;
129  s->radius = av_clip((s->radius + 1) & ~1, 4, 32);
130 
133 
134  if (ARCH_X86)
136 
137  av_log(ctx, AV_LOG_VERBOSE, "threshold:%.2f radius:%d\n", s->strength, s->radius);
138 
139  return 0;
140 }
141 
142 static av_cold void uninit(AVFilterContext *ctx)
143 {
144  GradFunContext *s = ctx->priv;
145  av_freep(&s->buf);
146 }
147 
149 {
150  static const enum AVPixelFormat pix_fmts[] = {
157  };
158 
160 
161  return 0;
162 }
163 
164 static int config_input(AVFilterLink *inlink)
165 {
166  GradFunContext *s = inlink->dst->priv;
167  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
168  int hsub = desc->log2_chroma_w;
169  int vsub = desc->log2_chroma_h;
170 
171  av_freep(&s->buf);
172  s->buf = av_calloc((FFALIGN(inlink->w, 16) * (s->radius + 1) / 2 + 32), sizeof(*s->buf));
173  if (!s->buf)
174  return AVERROR(ENOMEM);
175 
176  s->chroma_w = FF_CEIL_RSHIFT(inlink->w, hsub);
177  s->chroma_h = FF_CEIL_RSHIFT(inlink->h, vsub);
178  s->chroma_r = av_clip(((((s->radius >> hsub) + (s->radius >> vsub)) / 2 ) + 1) & ~1, 4, 32);
179 
180  return 0;
181 }
182 
183 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
184 {
185  GradFunContext *s = inlink->dst->priv;
186  AVFilterLink *outlink = inlink->dst->outputs[0];
187  AVFrame *out;
188  int p, direct;
189 
190  if (av_frame_is_writable(in)) {
191  direct = 1;
192  out = in;
193  } else {
194  direct = 0;
195  out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
196  if (!out) {
197  av_frame_free(&in);
198  return AVERROR(ENOMEM);
199  }
200  av_frame_copy_props(out, in);
201  }
202 
203  for (p = 0; p < 4 && in->data[p] && in->linesize[p]; p++) {
204  int w = inlink->w;
205  int h = inlink->h;
206  int r = s->radius;
207  if (p) {
208  w = s->chroma_w;
209  h = s->chroma_h;
210  r = s->chroma_r;
211  }
212 
213  if (FFMIN(w, h) > 2 * r)
214  filter(s, out->data[p], in->data[p], w, h, out->linesize[p], in->linesize[p], r);
215  else if (out->data[p] != in->data[p])
216  av_image_copy_plane(out->data[p], out->linesize[p], in->data[p], in->linesize[p], w, h);
217  }
218 
219  if (!direct)
220  av_frame_free(&in);
221 
222  return ff_filter_frame(outlink, out);
223 }
224 
225 #define OFFSET(x) offsetof(GradFunContext, x)
226 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
227 
228 static const AVOption gradfun_options[] = {
229  { "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 },
230  { "radius", "The neighborhood to fit the gradient to.", OFFSET(radius), AV_OPT_TYPE_INT, { .i64 = 16 }, 4, 32, FLAGS },
231  { NULL }
232 };
233 
234 AVFILTER_DEFINE_CLASS(gradfun);
235 
237  {
238  .name = "default",
239  .type = AVMEDIA_TYPE_VIDEO,
240  .config_props = config_input,
241  .filter_frame = filter_frame,
242  },
243  { NULL }
244 };
245 
247  {
248  .name = "default",
249  .type = AVMEDIA_TYPE_VIDEO,
250  },
251  { NULL }
252 };
253 
255  .name = "gradfun",
256  .description = NULL_IF_CONFIG_SMALL("Debands video quickly using gradients."),
257  .priv_size = sizeof(GradFunContext),
258  .priv_class = &gradfun_class,
259  .init = init,
260  .uninit = uninit,
262  .inputs = avfilter_vf_gradfun_inputs,
263  .outputs = avfilter_vf_gradfun_outputs,
265 };