Libav
vf_fps.c
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1 /*
2  * This file is part of Libav.
3  *
4  * Libav is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * Libav is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with Libav; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
24 #include <float.h>
25 #include <stdint.h>
26 
27 #include "libavutil/common.h"
28 #include "libavutil/fifo.h"
29 #include "libavutil/mathematics.h"
30 #include "libavutil/opt.h"
31 #include "libavutil/parseutils.h"
32 
33 #include "avfilter.h"
34 #include "internal.h"
35 #include "video.h"
36 
37 typedef struct FPSContext {
38  const AVClass *class;
39 
41 
42  /* timestamps in input timebase */
43  int64_t first_pts;
44  int64_t pts;
45 
46  double start_time;
47 
49  char *fps;
50 
51  /* statistics */
52  int frames_in;
53  int frames_out;
54  int dup;
55  int drop;
56 } FPSContext;
57 
58 #define OFFSET(x) offsetof(FPSContext, x)
59 #define V AV_OPT_FLAG_VIDEO_PARAM
60 static const AVOption options[] = {
61  { "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
62  { "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 },
63  { NULL },
64 };
65 
66 static const AVClass class = {
67  .class_name = "FPS filter",
68  .item_name = av_default_item_name,
69  .option = options,
71 };
72 
73 static av_cold int init(AVFilterContext *ctx)
74 {
75  FPSContext *s = ctx->priv;
76  int ret;
77 
78  if ((ret = av_parse_video_rate(&s->framerate, s->fps)) < 0) {
79  av_log(ctx, AV_LOG_ERROR, "Error parsing framerate %s.\n", s->fps);
80  return ret;
81  }
82 
83  if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFrame*))))
84  return AVERROR(ENOMEM);
85 
86  s->pts = AV_NOPTS_VALUE;
88 
89  av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
90  return 0;
91 }
92 
93 static void flush_fifo(AVFifoBuffer *fifo)
94 {
95  while (av_fifo_size(fifo)) {
96  AVFrame *tmp;
97  av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
98  av_frame_free(&tmp);
99  }
100 }
101 
102 static av_cold void uninit(AVFilterContext *ctx)
103 {
104  FPSContext *s = ctx->priv;
105  if (s->fifo) {
106  s->drop += av_fifo_size(s->fifo) / sizeof(AVFilterBufferRef*);
107  flush_fifo(s->fifo);
108  av_fifo_free(s->fifo);
109  }
110 
111  av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
112  "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
113 }
114 
115 static int config_props(AVFilterLink* link)
116 {
117  FPSContext *s = link->src->priv;
118 
119  link->time_base = (AVRational){ s->framerate.den, s->framerate.num };
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 
157 static int write_to_fifo(AVFifoBuffer *fifo, AVFrame *buf)
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) {
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) {
209  return write_to_fifo(s->fifo, buf);
210  }
211 
212  /* number of output frames */
213  delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
214  outlink->time_base);
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 
297  .init = init,
298  .uninit = uninit,
299 
300  .priv_size = sizeof(FPSContext),
301  .priv_class = &class,
302 
303  .inputs = avfilter_vf_fps_inputs,
304  .outputs = avfilter_vf_fps_outputs,
305 };