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vf_interlace.c
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1 /*
2  * Copyright (c) 2003 Michael Zucchi <notzed@ximian.com>
3  * Copyright (c) 2010 Baptiste Coudurier
4  * Copyright (c) 2011 Stefano Sabatini
5  * Copyright (c) 2013 Vittorio Giovara <vittorio.giovara@gmail.com>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License along
20  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22  */
23 
24 /**
25  * @file
26  * progressive to interlaced content filter, inspired by heavy debugging of tinterlace filter
27  */
28 
29 #include "libavutil/common.h"
30 #include "libavutil/opt.h"
31 #include "libavutil/imgutils.h"
32 #include "libavutil/avassert.h"
33 
34 #include "formats.h"
35 #include "avfilter.h"
36 #include "internal.h"
37 #include "version.h"
38 #include "video.h"
39 
40 enum ScanMode {
41  MODE_TFF = 0,
42  MODE_BFF = 1,
43 };
44 
45 enum FieldType {
48 };
49 
50 typedef struct InterlaceContext {
51  const AVClass *class;
52  enum ScanMode scan; // top or bottom field first scanning
53 #if FF_API_INTERLACE_LOWPASS_SET
54  int lowpass; // enable or disable low pass filterning
55 #endif
56  AVFrame *cur, *next; // the two frames from which the new one is obtained
58 
59 #define OFFSET(x) offsetof(InterlaceContext, x)
60 #define V AV_OPT_FLAG_VIDEO_PARAM
61 static const AVOption interlace_options[] = {
62  { "scan", "scanning mode", OFFSET(scan),
63  AV_OPT_TYPE_INT, {.i64 = MODE_TFF }, 0, 1, .flags = V, .unit = "scan" },
64  { "tff", "top field first", 0,
65  AV_OPT_TYPE_CONST, {.i64 = MODE_TFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
66  { "bff", "bottom field first", 0,
67  AV_OPT_TYPE_CONST, {.i64 = MODE_BFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
68 #if FF_API_INTERLACE_LOWPASS_SET
69  { "lowpass", "(deprecated, this option is always set)", OFFSET(lowpass),
70  AV_OPT_TYPE_INT, {.i64 = 1 }, 0, 1, .flags = V },
71 #endif
72  { NULL }
73 };
74 
75 AVFILTER_DEFINE_CLASS(interlace);
76 
77 static const enum AVPixelFormat formats_supported[] = {
82 };
83 
85 {
87  return 0;
88 }
89 
90 static av_cold void uninit(AVFilterContext *ctx)
91 {
92  InterlaceContext *s = ctx->priv;
93 
94  av_frame_free(&s->cur);
95  av_frame_free(&s->next);
96 }
97 
98 static int config_out_props(AVFilterLink *outlink)
99 {
100  AVFilterContext *ctx = outlink->src;
101  AVFilterLink *inlink = outlink->src->inputs[0];
102  InterlaceContext *s = ctx->priv;
103 
104 #if FF_API_INTERLACE_LOWPASS_SET
105  if (!s->lowpass)
106  av_log(ctx, AV_LOG_WARNING, "This option is deprecated and always set.\n");
107 #endif
108 
109  if (inlink->h < 2) {
110  av_log(ctx, AV_LOG_ERROR, "input video height is too small\n");
111  return AVERROR_INVALIDDATA;
112  }
113  // same input size
114  outlink->w = inlink->w;
115  outlink->h = inlink->h;
116  outlink->time_base = inlink->time_base;
117  outlink->frame_rate = inlink->frame_rate;
118  // half framerate
119  outlink->time_base.num *= 2;
120  outlink->frame_rate.den *= 2;
121  outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
122 
123  av_log(ctx, AV_LOG_VERBOSE, "%s interlacing\n",
124  s->scan == MODE_TFF ? "tff" : "bff");
125 
126  return 0;
127 }
128 
129 static void copy_picture_field(AVFrame *src_frame, AVFrame *dst_frame,
130  AVFilterLink *inlink, enum FieldType field_type)
131 {
132  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
133  int vsub = desc->log2_chroma_h;
134  int plane, i, j;
135 
136  for (plane = 0; plane < desc->nb_components; plane++) {
137  int lines = (plane == 1 || plane == 2) ? FF_CEIL_RSHIFT(inlink->h, vsub) : inlink->h;
138  int linesize = av_image_get_linesize(inlink->format, inlink->w, plane);
139  uint8_t *dstp = dst_frame->data[plane];
140  const uint8_t *srcp = src_frame->data[plane];
141  int srcp_linesize;
142  int dstp_linesize;
143 
144  av_assert0(linesize >= 0);
145 
146  lines = (lines + (field_type == FIELD_UPPER)) / 2;
147  if (field_type == FIELD_LOWER)
148  srcp += src_frame->linesize[plane];
149  if (field_type == FIELD_LOWER)
150  dstp += dst_frame->linesize[plane];
151 
152  srcp_linesize = src_frame->linesize[plane] * 2;
153  dstp_linesize = dst_frame->linesize[plane] * 2;
154  for (j = lines; j > 0; j--) {
155  const uint8_t *srcp_above = srcp - src_frame->linesize[plane];
156  const uint8_t *srcp_below = srcp + src_frame->linesize[plane];
157  if (j == lines)
158  srcp_above = srcp; // there is no line above
159  if (j == 1)
160  srcp_below = srcp; // there is no line below
161  for (i = 0; i < linesize; i++) {
162  // this calculation is an integer representation of
163  // '0.5 * current + 0.25 * above + 0.25 * below'
164  // '1 +' is for rounding.
165  dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
166  }
167  dstp += dstp_linesize;
168  srcp += srcp_linesize;
169  }
170  }
171 }
172 
173 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
174 {
175  AVFilterContext *ctx = inlink->dst;
176  AVFilterLink *outlink = ctx->outputs[0];
177  InterlaceContext *s = ctx->priv;
178  AVFrame *out;
179  int tff, ret;
180 
181  av_frame_free(&s->cur);
182  s->cur = s->next;
183  s->next = buf;
184 
185  /* we need at least two frames */
186  if (!s->cur || !s->next)
187  return 0;
188 
189  if (s->cur->interlaced_frame) {
190  av_log(ctx, AV_LOG_WARNING,
191  "video is already interlaced, adjusting framerate only\n");
192  out = av_frame_clone(s->cur);
193  if (!out)
194  return AVERROR(ENOMEM);
195  out->pts /= 2; // adjust pts to new framerate
196  ret = ff_filter_frame(outlink, out);
197  return ret;
198  }
199 
200  tff = (s->scan == MODE_TFF);
201  out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
202  if (!out)
203  return AVERROR(ENOMEM);
204 
205  av_frame_copy_props(out, s->cur);
206  out->interlaced_frame = 1;
207  out->top_field_first = tff;
208  out->pts /= 2; // adjust pts to new framerate
209 
210  /* copy upper/lower field from cur */
211  copy_picture_field(s->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER);
212  av_frame_free(&s->cur);
213 
214  /* copy lower/upper field from next */
215  copy_picture_field(s->next, out, inlink, tff ? FIELD_LOWER : FIELD_UPPER);
216  av_frame_free(&s->next);
217 
218  ret = ff_filter_frame(outlink, out);
219 
220  return ret;
221 }
222 
223 static const AVFilterPad inputs[] = {
224  {
225  .name = "default",
226  .type = AVMEDIA_TYPE_VIDEO,
227  .filter_frame = filter_frame,
228  },
229  { NULL }
230 };
231 
232 static const AVFilterPad outputs[] = {
233  {
234  .name = "default",
235  .type = AVMEDIA_TYPE_VIDEO,
236  .config_props = config_out_props,
237  },
238  { NULL }
239 };
240 
242  .name = "interlace",
243  .description = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
244  .uninit = uninit,
245  .priv_class = &interlace_class,
246  .priv_size = sizeof(InterlaceContext),
248  .inputs = inputs,
249  .outputs = outputs,
250 };