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vf_fps.c
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1 /*
2  * Copyright 2007 Bobby Bingham
3  * Copyright 2012 Robert Nagy <ronag89 gmail com>
4  * Copyright 2012 Anton Khirnov <anton khirnov net>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * a filter enforcing given constant framerate
26  */
27 
28 #include <float.h>
29 #include <stdint.h>
30 
31 #include "libavutil/common.h"
32 #include "libavutil/fifo.h"
33 #include "libavutil/mathematics.h"
34 #include "libavutil/opt.h"
35 #include "libavutil/parseutils.h"
36 
37 #include "avfilter.h"
38 #include "internal.h"
39 #include "video.h"
40 
41 typedef struct FPSContext {
42  const AVClass *class;
43 
44  AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
45 
46  /* timestamps in input timebase */
47  int64_t first_pts; ///< pts of the first frame that arrived on this filter
48 
49  double start_time; ///< pts, in seconds, of the expected first frame
50 
51  AVRational framerate; ///< target framerate
52  int rounding; ///< AVRounding method for timestamps
53 
54  /* statistics */
55  int frames_in; ///< number of frames on input
56  int frames_out; ///< number of frames on output
57  int dup; ///< number of frames duplicated
58  int drop; ///< number of framed dropped
59 } FPSContext;
60 
61 #define OFFSET(x) offsetof(FPSContext, x)
62 #define V AV_OPT_FLAG_VIDEO_PARAM
63 #define F AV_OPT_FLAG_FILTERING_PARAM
64 static const AVOption fps_options[] = {
65  { "fps", "A string describing desired output framerate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, { .str = "25" }, .flags = V|F },
66  { "start_time", "Assume the first PTS should be this value.", OFFSET(start_time), AV_OPT_TYPE_DOUBLE, { .dbl = DBL_MAX}, -DBL_MAX, DBL_MAX, V },
67  { "round", "set rounding method for timestamps", OFFSET(rounding), AV_OPT_TYPE_INT, { .i64 = AV_ROUND_NEAR_INF }, 0, 5, V|F, "round" },
68  { "zero", "round towards 0", OFFSET(rounding), AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_ZERO }, 0, 5, V|F, "round" },
69  { "inf", "round away from 0", OFFSET(rounding), AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_INF }, 0, 5, V|F, "round" },
70  { "down", "round towards -infty", OFFSET(rounding), AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_DOWN }, 0, 5, V|F, "round" },
71  { "up", "round towards +infty", OFFSET(rounding), AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_UP }, 0, 5, V|F, "round" },
72  { "near", "round to nearest", OFFSET(rounding), AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_NEAR_INF }, 0, 5, V|F, "round" },
73  { NULL }
74 };
75 
77 
78 static av_cold int init(AVFilterContext *ctx)
79 {
80  FPSContext *s = ctx->priv;
81 
82  if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFrame*))))
83  return AVERROR(ENOMEM);
84 
86 
87  av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
88  return 0;
89 }
90 
91 static void flush_fifo(AVFifoBuffer *fifo)
92 {
93  while (av_fifo_size(fifo)) {
94  AVFrame *tmp;
95  av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
96  av_frame_free(&tmp);
97  }
98 }
99 
100 static av_cold void uninit(AVFilterContext *ctx)
101 {
102  FPSContext *s = ctx->priv;
103  if (s->fifo) {
104  s->drop += av_fifo_size(s->fifo) / sizeof(AVFrame*);
105  flush_fifo(s->fifo);
106  av_fifo_free(s->fifo);
107  }
108 
109  av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
110  "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
111 }
112 
113 static int config_props(AVFilterLink* link)
114 {
115  FPSContext *s = link->src->priv;
116 
117  link->time_base = av_inv_q(s->framerate);
118  link->frame_rate= s->framerate;
119  link->w = link->src->inputs[0]->w;
120  link->h = link->src->inputs[0]->h;
121 
122  return 0;
123 }
124 
125 static int request_frame(AVFilterLink *outlink)
126 {
127  AVFilterContext *ctx = outlink->src;
128  FPSContext *s = ctx->priv;
129  int frames_out = s->frames_out;
130  int ret = 0;
131 
132  while (ret >= 0 && s->frames_out == frames_out)
133  ret = ff_request_frame(ctx->inputs[0]);
134 
135  /* flush the fifo */
136  if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
137  int i;
138  for (i = 0; av_fifo_size(s->fifo); i++) {
139  AVFrame *buf;
140 
141  av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
142  buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
143  outlink->time_base) + s->frames_out;
144 
145  if ((ret = ff_filter_frame(outlink, buf)) < 0)
146  return ret;
147 
148  s->frames_out++;
149  }
150  return 0;
151  }
152 
153  return ret;
154 }
155 
157 {
158  int ret;
159 
160  if (!av_fifo_space(fifo) &&
161  (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {
162  av_frame_free(&buf);
163  return ret;
164  }
165 
166  av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
167  return 0;
168 }
169 
170 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
171 {
172  AVFilterContext *ctx = inlink->dst;
173  FPSContext *s = ctx->priv;
174  AVFilterLink *outlink = ctx->outputs[0];
175  int64_t delta;
176  int i, ret;
177 
178  s->frames_in++;
179  /* discard frames until we get the first timestamp */
180  if (s->first_pts == AV_NOPTS_VALUE) {
181  if (buf->pts != AV_NOPTS_VALUE) {
182  ret = write_to_fifo(s->fifo, buf);
183  if (ret < 0)
184  return ret;
185 
186  if (s->start_time != DBL_MAX && s->start_time != AV_NOPTS_VALUE) {
187  double first_pts = s->start_time * AV_TIME_BASE;
188  first_pts = FFMIN(FFMAX(first_pts, INT64_MIN), INT64_MAX);
189  s->first_pts = av_rescale_q(first_pts, AV_TIME_BASE_Q,
190  inlink->time_base);
191  av_log(ctx, AV_LOG_VERBOSE, "Set first pts to (in:%"PRId64" out:%"PRId64")\n",
192  s->first_pts, av_rescale_q(first_pts, AV_TIME_BASE_Q,
193  outlink->time_base));
194  } else {
195  s->first_pts = buf->pts;
196  }
197  } else {
198  av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
199  "timestamp.\n");
200  av_frame_free(&buf);
201  s->drop++;
202  }
203  return 0;
204  }
205 
206  /* now wait for the next timestamp */
207  if (buf->pts == AV_NOPTS_VALUE || av_fifo_size(s->fifo) <= 0) {
208  return write_to_fifo(s->fifo, buf);
209  }
210 
211  /* number of output frames */
212  delta = av_rescale_q_rnd(buf->pts - s->first_pts, inlink->time_base,
213  outlink->time_base, s->rounding) - s->frames_out ;
214 
215  if (delta < 1) {
216  /* drop the frame and everything buffered except the first */
217  AVFrame *tmp;
218  int drop = av_fifo_size(s->fifo)/sizeof(AVFrame*);
219 
220  av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
221  s->drop += drop;
222 
223  av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
224  flush_fifo(s->fifo);
225  ret = write_to_fifo(s->fifo, tmp);
226 
227  av_frame_free(&buf);
228  return ret;
229  }
230 
231  /* can output >= 1 frames */
232  for (i = 0; i < delta; i++) {
233  AVFrame *buf_out;
234  av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
235 
236  /* duplicate the frame if needed */
237  if (!av_fifo_size(s->fifo) && i < delta - 1) {
238  AVFrame *dup = av_frame_clone(buf_out);
239 
240  av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
241  if (dup)
242  ret = write_to_fifo(s->fifo, dup);
243  else
244  ret = AVERROR(ENOMEM);
245 
246  if (ret < 0) {
247  av_frame_free(&buf_out);
248  av_frame_free(&buf);
249  return ret;
250  }
251 
252  s->dup++;
253  }
254 
255  buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
256  outlink->time_base) + s->frames_out;
257 
258  if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {
259  av_frame_free(&buf);
260  return ret;
261  }
262 
263  s->frames_out++;
264  }
265  flush_fifo(s->fifo);
266 
267  ret = write_to_fifo(s->fifo, buf);
268 
269  return ret;
270 }
271 
273  {
274  .name = "default",
275  .type = AVMEDIA_TYPE_VIDEO,
276  .filter_frame = filter_frame,
277  },
278  { NULL }
279 };
280 
282  {
283  .name = "default",
284  .type = AVMEDIA_TYPE_VIDEO,
285  .request_frame = request_frame,
286  .config_props = config_props
287  },
288  { NULL }
289 };
290 
292  .name = "fps",
293  .description = NULL_IF_CONFIG_SMALL("Force constant framerate."),
294  .init = init,
295  .uninit = uninit,
296  .priv_size = sizeof(FPSContext),
297  .priv_class = &fps_class,
298  .inputs = avfilter_vf_fps_inputs,
299  .outputs = avfilter_vf_fps_outputs,
300 };