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 "libavutil/common.h"
25 #include "libavutil/fifo.h"
26 #include "libavutil/mathematics.h"
27 #include "libavutil/opt.h"
28 #include "libavutil/parseutils.h"
29 
30 #include "avfilter.h"
31 #include "internal.h"
32 #include "video.h"
33 
34 typedef struct FPSContext {
35  const AVClass *class;
36 
38 
39  /* timestamps in input timebase */
40  int64_t first_pts;
41  int64_t pts;
42 
44  char *fps;
45 
46  /* statistics */
47  int frames_in;
48  int frames_out;
49  int dup;
50  int drop;
51 } FPSContext;
52 
53 #define OFFSET(x) offsetof(FPSContext, x)
54 #define V AV_OPT_FLAG_VIDEO_PARAM
55 static const AVOption options[] = {
56  { "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
57  { NULL },
58 };
59 
60 static const AVClass class = {
61  .class_name = "FPS filter",
62  .item_name = av_default_item_name,
63  .option = options,
65 };
66 
67 static av_cold int init(AVFilterContext *ctx, const char *args)
68 {
69  FPSContext *s = ctx->priv;
70  int ret;
71 
72  s->class = &class;
74 
75  if ((ret = av_set_options_string(s, args, "=", ":")) < 0) {
76  av_log(ctx, AV_LOG_ERROR, "Error parsing the options string %s.\n",
77  args);
78  return ret;
79  }
80 
81  if ((ret = av_parse_video_rate(&s->framerate, s->fps)) < 0) {
82  av_log(ctx, AV_LOG_ERROR, "Error parsing framerate %s.\n", s->fps);
83  return ret;
84  }
85  av_opt_free(s);
86 
87  if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFilterBufferRef*))))
88  return AVERROR(ENOMEM);
89 
90  av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
91  return 0;
92 }
93 
94 static void flush_fifo(AVFifoBuffer *fifo)
95 {
96  while (av_fifo_size(fifo)) {
97  AVFilterBufferRef *tmp;
98  av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
100  }
101 }
102 
103 static av_cold void uninit(AVFilterContext *ctx)
104 {
105  FPSContext *s = ctx->priv;
106  if (s->fifo) {
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  s->pts = AV_NOPTS_VALUE;
123 
124  return 0;
125 }
126 
127 static int request_frame(AVFilterLink *outlink)
128 {
129  AVFilterContext *ctx = outlink->src;
130  FPSContext *s = ctx->priv;
131  int frames_out = s->frames_out;
132  int ret = 0;
133 
134  while (ret >= 0 && s->frames_out == frames_out)
135  ret = ff_request_frame(ctx->inputs[0]);
136 
137  /* flush the fifo */
138  if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
139  int i;
140  for (i = 0; av_fifo_size(s->fifo); i++) {
141  AVFilterBufferRef *buf;
142 
143  av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
144  buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
145  outlink->time_base) + s->frames_out;
146 
147  if ((ret = ff_filter_frame(outlink, buf)) < 0)
148  return ret;
149 
150  s->frames_out++;
151  }
152  return 0;
153  }
154 
155  return ret;
156 }
157 
159 {
160  int ret;
161 
162  if (!av_fifo_space(fifo) &&
163  (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {
165  return ret;
166  }
167 
168  av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
169  return 0;
170 }
171 
172 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *buf)
173 {
174  AVFilterContext *ctx = inlink->dst;
175  FPSContext *s = ctx->priv;
176  AVFilterLink *outlink = ctx->outputs[0];
177  int64_t delta;
178  int i, ret;
179 
180  s->frames_in++;
181  /* discard frames until we get the first timestamp */
182  if (s->pts == AV_NOPTS_VALUE) {
183  if (buf->pts != AV_NOPTS_VALUE) {
184  ret = write_to_fifo(s->fifo, buf);
185  if (ret < 0)
186  return ret;
187 
188  s->first_pts = s->pts = buf->pts;
189  } else {
190  av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
191  "timestamp.\n");
193  s->drop++;
194  }
195  return 0;
196  }
197 
198  /* now wait for the next timestamp */
199  if (buf->pts == AV_NOPTS_VALUE) {
200  return write_to_fifo(s->fifo, buf);
201  }
202 
203  /* number of output frames */
204  delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
205  outlink->time_base);
206 
207  if (delta < 1) {
208  /* drop the frame and everything buffered except the first */
209  AVFilterBufferRef *tmp;
210  int drop = av_fifo_size(s->fifo)/sizeof(AVFilterBufferRef*);
211 
212  av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
213  s->drop += drop;
214 
215  av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
216  flush_fifo(s->fifo);
217  ret = write_to_fifo(s->fifo, tmp);
218 
220  return ret;
221  }
222 
223  /* can output >= 1 frames */
224  for (i = 0; i < delta; i++) {
225  AVFilterBufferRef *buf_out;
226  av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
227 
228  /* duplicate the frame if needed */
229  if (!av_fifo_size(s->fifo) && i < delta - 1) {
231 
232  av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
233  if (dup)
234  ret = write_to_fifo(s->fifo, dup);
235  else
236  ret = AVERROR(ENOMEM);
237 
238  if (ret < 0) {
239  avfilter_unref_bufferp(&buf_out);
241  return ret;
242  }
243 
244  s->dup++;
245  }
246 
247  buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
248  outlink->time_base) + s->frames_out;
249 
250  if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {
252  return ret;
253  }
254 
255  s->frames_out++;
256  }
257  flush_fifo(s->fifo);
258 
259  ret = write_to_fifo(s->fifo, buf);
260  s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
261 
262  return ret;
263 }
264 
266  {
267  .name = "default",
268  .type = AVMEDIA_TYPE_VIDEO,
269  .filter_frame = filter_frame,
270  },
271  { NULL }
272 };
273 
275  {
276  .name = "default",
277  .type = AVMEDIA_TYPE_VIDEO,
278  .request_frame = request_frame,
279  .config_props = config_props
280  },
281  { NULL }
282 };
283 
285  .name = "fps",
286  .description = NULL_IF_CONFIG_SMALL("Force constant framerate"),
287 
288  .init = init,
289  .uninit = uninit,
290 
291  .priv_size = sizeof(FPSContext),
292 
293  .inputs = avfilter_vf_fps_inputs,
294  .outputs = avfilter_vf_fps_outputs,
295 };