vf_fade.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2010 Brandon Mintern
3  * Copyright (c) 2007 Bobby Bingham
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "libavutil/pixdesc.h"
29 #include "avfilter.h"
30 
31 typedef struct {
32  int factor, fade_per_frame;
33  unsigned int frame_index, start_frame, stop_frame;
34  int hsub, vsub, bpp;
35 } FadeContext;
36 
37 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
38 {
39  FadeContext *fade = ctx->priv;
40  unsigned int nb_frames;
41  char in_out[4];
42 
43  if (!args ||
44  sscanf(args, " %3[^:]:%u:%u", in_out, &fade->start_frame, &nb_frames) != 3) {
45  av_log(ctx, AV_LOG_ERROR,
46  "Expected 3 arguments '(in|out):#:#':'%s'\n", args);
47  return AVERROR(EINVAL);
48  }
49 
50  nb_frames = nb_frames ? nb_frames : 1;
51  fade->fade_per_frame = (1 << 16) / nb_frames;
52  if (!strcmp(in_out, "in"))
53  fade->factor = 0;
54  else if (!strcmp(in_out, "out")) {
55  fade->fade_per_frame = -fade->fade_per_frame;
56  fade->factor = (1 << 16);
57  } else {
58  av_log(ctx, AV_LOG_ERROR,
59  "first argument must be 'in' or 'out':'%s'\n", in_out);
60  return AVERROR(EINVAL);
61  }
62  fade->stop_frame = fade->start_frame + nb_frames;
63 
64  av_log(ctx, AV_LOG_INFO,
65  "type:%s start_frame:%d nb_frames:%d\n",
66  in_out, fade->start_frame, nb_frames);
67  return 0;
68 }
69 
71 {
72  static const enum PixelFormat pix_fmts[] = {
79  };
80 
82  return 0;
83 }
84 
85 static int config_props(AVFilterLink *inlink)
86 {
87  FadeContext *fade = inlink->dst->priv;
88  const AVPixFmtDescriptor *pixdesc = &av_pix_fmt_descriptors[inlink->format];
89 
90  fade->hsub = pixdesc->log2_chroma_w;
91  fade->vsub = pixdesc->log2_chroma_h;
92 
93  fade->bpp = av_get_bits_per_pixel(pixdesc) >> 3;
94  return 0;
95 }
96 
97 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
98 {
99  FadeContext *fade = inlink->dst->priv;
100  AVFilterBufferRef *outpic = inlink->cur_buf;
101  uint8_t *p;
102  int i, j, plane;
103 
104  if (fade->factor < UINT16_MAX) {
105  /* luma or rgb plane */
106  for (i = 0; i < h; i++) {
107  p = outpic->data[0] + (y+i) * outpic->linesize[0];
108  for (j = 0; j < inlink->w * fade->bpp; j++) {
109  /* fade->factor is using 16 lower-order bits for decimal
110  * places. 32768 = 1 << 15, it is an integer representation
111  * of 0.5 and is for rounding. */
112  *p = (*p * fade->factor + 32768) >> 16;
113  p++;
114  }
115  }
116 
117  if (outpic->data[1] && outpic->data[2]) {
118  /* chroma planes */
119  for (plane = 1; plane < 3; plane++) {
120  for (i = 0; i < h; i++) {
121  p = outpic->data[plane] + ((y+i) >> fade->vsub) * outpic->linesize[plane];
122  for (j = 0; j < inlink->w >> fade->hsub; j++) {
123  /* 8421367 = ((128 << 1) + 1) << 15. It is an integer
124  * representation of 128.5. The .5 is for rounding
125  * purposes. */
126  *p = ((*p - 128) * fade->factor + 8421367) >> 16;
127  p++;
128  }
129  }
130  }
131  }
132  }
133 
134  avfilter_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
135 }
136 
137 static void end_frame(AVFilterLink *inlink)
138 {
139  FadeContext *fade = inlink->dst->priv;
140 
141  avfilter_end_frame(inlink->dst->outputs[0]);
142 
143  if (fade->frame_index >= fade->start_frame &&
144  fade->frame_index <= fade->stop_frame)
145  fade->factor += fade->fade_per_frame;
146  fade->factor = av_clip_uint16(fade->factor);
147  fade->frame_index++;
148 }
149 
151  .name = "fade",
152  .description = NULL_IF_CONFIG_SMALL("Fade in/out input video"),
153  .init = init,
154  .priv_size = sizeof(FadeContext),
156 
157  .inputs = (AVFilterPad[]) {{ .name = "default",
158  .type = AVMEDIA_TYPE_VIDEO,
159  .config_props = config_props,
160  .get_video_buffer = avfilter_null_get_video_buffer,
161  .start_frame = avfilter_null_start_frame,
162  .draw_slice = draw_slice,
163  .end_frame = end_frame,
164  .min_perms = AV_PERM_READ | AV_PERM_WRITE,
165  .rej_perms = AV_PERM_PRESERVE, },
166  { .name = NULL}},
167  .outputs = (AVFilterPad[]) {{ .name = "default",
168  .type = AVMEDIA_TYPE_VIDEO, },
169  { .name = NULL}},
170 };