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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 
30 #include "libavutil/common.h"
31 #include "libavutil/fifo.h"
32 #include "libavutil/mathematics.h"
33 #include "libavutil/opt.h"
34 #include "libavutil/parseutils.h"
35 
36 #include "avfilter.h"
37 #include "internal.h"
38 #include "video.h"
39 
40 typedef struct FPSContext {
41  const AVClass *class;
42 
43  AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
44 
45  /* timestamps in input timebase */
46  int64_t first_pts; ///< pts of the first frame that arrived on this filter
47  int64_t pts; ///< pts of the first frame currently in the fifo
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 
85  s->pts = AV_NOPTS_VALUE;
87 
88  av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
89  return 0;
90 }
91 
92 static void flush_fifo(AVFifoBuffer *fifo)
93 {
94  while (av_fifo_size(fifo)) {
95  AVFrame *tmp;
96  av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
97  av_frame_free(&tmp);
98  }
99 }
100 
101 static av_cold void uninit(AVFilterContext *ctx)
102 {
103  FPSContext *s = ctx->priv;
104  if (s->fifo) {
105  s->drop += av_fifo_size(s->fifo) / sizeof(AVFrame*);
106  flush_fifo(s->fifo);
107  av_fifo_free(s->fifo);
108  }
109 
110  av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
111  "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
112 }
113 
114 static int config_props(AVFilterLink* link)
115 {
116  FPSContext *s = link->src->priv;
117 
118  link->time_base = av_inv_q(s->framerate);
119  link->frame_rate= s->framerate;
120  link->w = link->src->inputs[0]->w;
121  link->h = link->src->inputs[0]->h;
122 
123  return 0;
124 }
125 
126 static int request_frame(AVFilterLink *outlink)
127 {
128  AVFilterContext *ctx = outlink->src;
129  FPSContext *s = ctx->priv;
130  int frames_out = s->frames_out;
131  int ret = 0;
132 
133  while (ret >= 0 && s->frames_out == frames_out)
134  ret = ff_request_frame(ctx->inputs[0]);
135 
136  /* flush the fifo */
137  if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
138  int i;
139  for (i = 0; av_fifo_size(s->fifo); i++) {
140  AVFrame *buf;
141 
142  av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
143  buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
144  outlink->time_base) + s->frames_out;
145 
146  if ((ret = ff_filter_frame(outlink, buf)) < 0)
147  return ret;
148 
149  s->frames_out++;
150  }
151  return 0;
152  }
153 
154  return ret;
155 }
156 
158 {
159  int ret;
160 
161  if (!av_fifo_space(fifo) &&
162  (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {
163  av_frame_free(&buf);
164  return ret;
165  }
166 
167  av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
168  return 0;
169 }
170 
171 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
172 {
173  AVFilterContext *ctx = inlink->dst;
174  FPSContext *s = ctx->priv;
175  AVFilterLink *outlink = ctx->outputs[0];
176  int64_t delta;
177  int i, ret;
178 
179  s->frames_in++;
180  /* discard frames until we get the first timestamp */
181  if (s->pts == AV_NOPTS_VALUE) {
182  if (buf->pts != AV_NOPTS_VALUE) {
183  ret = write_to_fifo(s->fifo, buf);
184  if (ret < 0)
185  return ret;
186 
187  if (s->start_time != DBL_MAX && s->start_time != AV_NOPTS_VALUE) {
188  double first_pts = s->start_time * AV_TIME_BASE;
189  first_pts = FFMIN(FFMAX(first_pts, INT64_MIN), INT64_MAX);
190  s->first_pts = s->pts = av_rescale_q(first_pts, AV_TIME_BASE_Q,
191  inlink->time_base);
192  av_log(ctx, AV_LOG_VERBOSE, "Set first pts to (in:%"PRId64" out:%"PRId64")\n",
193  s->first_pts, av_rescale_q(first_pts, AV_TIME_BASE_Q,
194  outlink->time_base));
195  } else {
196  s->first_pts = s->pts = buf->pts;
197  }
198  } else {
199  av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
200  "timestamp.\n");
201  av_frame_free(&buf);
202  s->drop++;
203  }
204  return 0;
205  }
206 
207  /* now wait for the next timestamp */
208  if (buf->pts == AV_NOPTS_VALUE || av_fifo_size(s->fifo) <= 0) {
209  return write_to_fifo(s->fifo, buf);
210  }
211 
212  /* number of output frames */
213  delta = av_rescale_q_rnd(buf->pts - s->pts, inlink->time_base,
214  outlink->time_base, s->rounding);
215 
216  if (delta < 1) {
217  /* drop the frame and everything buffered except the first */
218  AVFrame *tmp;
219  int drop = av_fifo_size(s->fifo)/sizeof(AVFrame*);
220 
221  av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
222  s->drop += drop;
223 
224  av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
225  flush_fifo(s->fifo);
226  ret = write_to_fifo(s->fifo, tmp);
227 
228  av_frame_free(&buf);
229  return ret;
230  }
231 
232  /* can output >= 1 frames */
233  for (i = 0; i < delta; i++) {
234  AVFrame *buf_out;
235  av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
236 
237  /* duplicate the frame if needed */
238  if (!av_fifo_size(s->fifo) && i < delta - 1) {
239  AVFrame *dup = av_frame_clone(buf_out);
240 
241  av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
242  if (dup)
243  ret = write_to_fifo(s->fifo, dup);
244  else
245  ret = AVERROR(ENOMEM);
246 
247  if (ret < 0) {
248  av_frame_free(&buf_out);
249  av_frame_free(&buf);
250  return ret;
251  }
252 
253  s->dup++;
254  }
255 
256  buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
257  outlink->time_base) + s->frames_out;
258 
259  if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {
260  av_frame_free(&buf);
261  return ret;
262  }
263 
264  s->frames_out++;
265  }
266  flush_fifo(s->fifo);
267 
268  ret = write_to_fifo(s->fifo, buf);
269  s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
270 
271  return ret;
272 }
273 
275  {
276  .name = "default",
277  .type = AVMEDIA_TYPE_VIDEO,
278  .filter_frame = filter_frame,
279  },
280  { NULL }
281 };
282 
284  {
285  .name = "default",
286  .type = AVMEDIA_TYPE_VIDEO,
287  .request_frame = request_frame,
288  .config_props = config_props
289  },
290  { NULL }
291 };
292 
294  .name = "fps",
295  .description = NULL_IF_CONFIG_SMALL("Force constant framerate."),
296  .init = init,
297  .uninit = uninit,
298  .priv_size = sizeof(FPSContext),
299  .priv_class = &fps_class,
300  .inputs = avfilter_vf_fps_inputs,
301  .outputs = avfilter_vf_fps_outputs,
302 };