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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.washignton.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/pixdesc.h"
39 #include "libavutil/opt.h"
40 #include "avfilter.h"
41 #include "formats.h"
42 #include "gradfun.h"
43 #include "internal.h"
44 #include "video.h"
45 
46 #define OFFSET(x) offsetof(GradFunContext, x)
47 #define F AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
48 
49 static const AVOption gradfun_options[] = {
50  { "strength", "set the maximum amount by which the filter will change any one pixel", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl = 1.2}, 0.51, 64, F },
51  { "radius", "set the neighborhood to fit the gradient to", OFFSET(radius), AV_OPT_TYPE_INT, {.i64 = 16}, 4, 32, F },
52  { NULL }
53 };
54 
55 AVFILTER_DEFINE_CLASS(gradfun);
56 
57 DECLARE_ALIGNED(16, static const uint16_t, dither)[8][8] = {
58  {0x00,0x60,0x18,0x78,0x06,0x66,0x1E,0x7E},
59  {0x40,0x20,0x58,0x38,0x46,0x26,0x5E,0x3E},
60  {0x10,0x70,0x08,0x68,0x16,0x76,0x0E,0x6E},
61  {0x50,0x30,0x48,0x28,0x56,0x36,0x4E,0x2E},
62  {0x04,0x64,0x1C,0x7C,0x02,0x62,0x1A,0x7A},
63  {0x44,0x24,0x5C,0x3C,0x42,0x22,0x5A,0x3A},
64  {0x14,0x74,0x0C,0x6C,0x12,0x72,0x0A,0x6A},
65  {0x54,0x34,0x4C,0x2C,0x52,0x32,0x4A,0x2A},
66 };
67 
68 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)
69 {
70  int x;
71  for (x = 0; x < width; dc += x & 1, x++) {
72  int pix = src[x] << 7;
73  int delta = dc[0] - pix;
74  int m = abs(delta) * thresh >> 16;
75  m = FFMAX(0, 127 - m);
76  m = m * m * delta >> 14;
77  pix += m + dithers[x & 7];
78  dst[x] = av_clip_uint8(pix >> 7);
79  }
80 }
81 
82 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)
83 {
84  int x, v, old;
85  for (x = 0; x < width; x++) {
86  v = buf1[x] + src[2 * x] + src[2 * x + 1] + src[2 * x + src_linesize] + src[2 * x + 1 + src_linesize];
87  old = buf[x];
88  buf[x] = v;
89  dc[x] = v - old;
90  }
91 }
92 
93 static void filter(GradFunContext *ctx, uint8_t *dst, const uint8_t *src, int width, int height, int dst_linesize, int src_linesize, int r)
94 {
95  int bstride = FFALIGN(width, 16) / 2;
96  int y;
97  uint32_t dc_factor = (1 << 21) / (r * r);
98  uint16_t *dc = ctx->buf + 16;
99  uint16_t *buf = ctx->buf + bstride + 32;
100  int thresh = ctx->thresh;
101 
102  memset(dc, 0, (bstride + 16) * sizeof(*buf));
103  for (y = 0; y < r; y++)
104  ctx->blur_line(dc, buf + y * bstride, buf + (y - 1) * bstride, src + 2 * y * src_linesize, src_linesize, width / 2);
105  for (;;) {
106  if (y < height - r) {
107  int mod = ((y + r) / 2) % r;
108  uint16_t *buf0 = buf + mod * bstride;
109  uint16_t *buf1 = buf + (mod ? mod - 1 : r - 1) * bstride;
110  int x, v;
111  ctx->blur_line(dc, buf0, buf1, src + (y + r) * src_linesize, src_linesize, width / 2);
112  for (x = v = 0; x < r; x++)
113  v += dc[x];
114  for (; x < width / 2; x++) {
115  v += dc[x] - dc[x-r];
116  dc[x-r] = v * dc_factor >> 16;
117  }
118  for (; x < (width + r + 1) / 2; x++)
119  dc[x-r] = v * dc_factor >> 16;
120  for (x = -r / 2; x < 0; x++)
121  dc[x] = dc[0];
122  }
123  if (y == r) {
124  for (y = 0; y < r; y++)
125  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
126  }
127  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
128  if (++y >= height) break;
129  ctx->filter_line(dst + y * dst_linesize, src + y * src_linesize, dc - r / 2, width, thresh, dither[y & 7]);
130  if (++y >= height) break;
131  }
132 }
133 
134 static av_cold int init(AVFilterContext *ctx, const char *args)
135 {
136  int ret;
137  GradFunContext *gf = ctx->priv;
138  static const char *shorthand[] = { "strength", "radius", NULL };
139 
140  gf->class = &gradfun_class;
142 
143  if ((ret = av_opt_set_from_string(gf, args, shorthand, "=", ":")) < 0)
144  return ret;
145 
146  gf->thresh = (1 << 15) / gf->strength;
147  gf->radius = av_clip((gf->radius + 1) & ~1, 4, 32);
148 
151 
152  if (ARCH_X86)
154 
155  av_log(ctx, AV_LOG_VERBOSE, "threshold:%.2f radius:%d\n", gf->strength, gf->radius);
156 
157  return 0;
158 }
159 
160 static av_cold void uninit(AVFilterContext *ctx)
161 {
162  GradFunContext *gf = ctx->priv;
163  av_freep(&gf->buf);
164 }
165 
167 {
168  static const enum AVPixelFormat pix_fmts[] = {
175  };
176 
178 
179  return 0;
180 }
181 
182 static int config_input(AVFilterLink *inlink)
183 {
184  GradFunContext *gf = inlink->dst->priv;
185  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
186  int hsub = desc->log2_chroma_w;
187  int vsub = desc->log2_chroma_h;
188 
189  gf->buf = av_mallocz((FFALIGN(inlink->w, 16) * (gf->radius + 1) / 2 + 32) * sizeof(uint16_t));
190  if (!gf->buf)
191  return AVERROR(ENOMEM);
192 
193  gf->chroma_w = -((-inlink->w) >> hsub);
194  gf->chroma_h = -((-inlink->h) >> vsub);
195  gf->chroma_r = av_clip(((((gf->radius >> hsub) + (gf->radius >> vsub)) / 2 ) + 1) & ~1, 4, 32);
196 
197  return 0;
198 }
199 
201 {
202  GradFunContext *gf = inlink->dst->priv;
203  AVFilterLink *outlink = inlink->dst->outputs[0];
205  int p, direct = 0;
206 
207  if (in->perms & AV_PERM_WRITE) {
208  direct = 1;
209  out = in;
210  } else {
211  out = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
212  if (!out) {
214  return AVERROR(ENOMEM);
215  }
217  }
218 
219  for (p = 0; p < 4 && in->data[p]; p++) {
220  int w = inlink->w;
221  int h = inlink->h;
222  int r = gf->radius;
223  if (p) {
224  w = gf->chroma_w;
225  h = gf->chroma_h;
226  r = gf->chroma_r;
227  }
228 
229  if (FFMIN(w, h) > 2 * r)
230  filter(gf, out->data[p], in->data[p], w, h, out->linesize[p], in->linesize[p], r);
231  else if (out->data[p] != in->data[p])
232  av_image_copy_plane(out->data[p], out->linesize[p], in->data[p], in->linesize[p], w, h);
233  }
234 
235  if (!direct)
237 
238  return ff_filter_frame(outlink, out);
239 }
240 
242  {
243  .name = "default",
244  .type = AVMEDIA_TYPE_VIDEO,
245  .config_props = config_input,
246  .filter_frame = filter_frame,
247  .min_perms = AV_PERM_READ,
248  },
249  { NULL }
250 };
251 
253  {
254  .name = "default",
255  .type = AVMEDIA_TYPE_VIDEO,
256  },
257  { NULL }
258 };
259 
261  .name = "gradfun",
262  .description = NULL_IF_CONFIG_SMALL("Debands video quickly using gradients."),
263  .priv_size = sizeof(GradFunContext),
264  .init = init,
265  .uninit = uninit,
267  .inputs = avfilter_vf_gradfun_inputs,
268  .outputs = avfilter_vf_gradfun_outputs,
269  .priv_class = &gradfun_class,
270 };