2 * This file is part of Libav.
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.
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.
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
21 * a filter enforcing given constant framerate
26 #include "libavutil/common.h"
27 #include "libavutil/fifo.h"
28 #include "libavutil/mathematics.h"
29 #include "libavutil/opt.h"
30 #include "libavutil/parseutils.h"
36 typedef struct FPSContext {
39 AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
41 /* timestamps in input timebase */
42 int64_t first_pts; ///< pts of the first frame that arrived on this filter
43 int64_t pts; ///< pts of the first frame currently in the fifo
45 double start_time; ///< pts, in seconds, of the expected first frame
47 AVRational framerate; ///< target framerate
48 char *fps; ///< a string describing target framerate
51 int frames_in; ///< number of frames on input
52 int frames_out; ///< number of frames on output
53 int dup; ///< number of frames duplicated
54 int drop; ///< number of framed dropped
57 #define OFFSET(x) offsetof(FPSContext, x)
58 #define V AV_OPT_FLAG_VIDEO_PARAM
59 static const AVOption options[] = {
60 { "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
61 { "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 },
65 static const AVClass class = {
66 .class_name = "FPS filter",
67 .item_name = av_default_item_name,
69 .version = LIBAVUTIL_VERSION_INT,
72 static av_cold int init(AVFilterContext *ctx)
74 FPSContext *s = ctx->priv;
77 if ((ret = av_parse_video_rate(&s->framerate, s->fps)) < 0) {
78 av_log(ctx, AV_LOG_ERROR, "Error parsing framerate %s.\n", s->fps);
82 if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFrame*))))
83 return AVERROR(ENOMEM);
85 s->pts = AV_NOPTS_VALUE;
86 s->first_pts = AV_NOPTS_VALUE;
88 av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
92 static void flush_fifo(AVFifoBuffer *fifo)
94 while (av_fifo_size(fifo)) {
96 av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
101 static av_cold void uninit(AVFilterContext *ctx)
103 FPSContext *s = ctx->priv;
105 s->drop += av_fifo_size(s->fifo) / sizeof(AVFilterBufferRef*);
107 av_fifo_free(s->fifo);
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);
114 static int config_props(AVFilterLink* link)
116 FPSContext *s = link->src->priv;
118 link->time_base = (AVRational){ s->framerate.den, s->framerate.num };
119 link->w = link->src->inputs[0]->w;
120 link->h = link->src->inputs[0]->h;
125 static int request_frame(AVFilterLink *outlink)
127 AVFilterContext *ctx = outlink->src;
128 FPSContext *s = ctx->priv;
129 int frames_out = s->frames_out;
132 while (ret >= 0 && s->frames_out == frames_out)
133 ret = ff_request_frame(ctx->inputs[0]);
136 if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
138 for (i = 0; av_fifo_size(s->fifo); i++) {
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;
145 if ((ret = ff_filter_frame(outlink, buf)) < 0)
156 static int write_to_fifo(AVFifoBuffer *fifo, AVFrame *buf)
160 if (!av_fifo_space(fifo) &&
161 (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {
166 av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
170 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
172 AVFilterContext *ctx = inlink->dst;
173 FPSContext *s = ctx->priv;
174 AVFilterLink *outlink = ctx->outputs[0];
179 /* discard frames until we get the first timestamp */
180 if (s->pts == AV_NOPTS_VALUE) {
181 if (buf->pts != AV_NOPTS_VALUE) {
182 ret = write_to_fifo(s->fifo, buf);
186 if (s->start_time != DBL_MAX) {
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 = s->pts = av_rescale_q(first_pts, AV_TIME_BASE_Q,
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));
195 s->first_pts = s->pts = buf->pts;
198 av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
206 /* now wait for the next timestamp */
207 if (buf->pts == AV_NOPTS_VALUE) {
208 return write_to_fifo(s->fifo, buf);
211 /* number of output frames */
212 delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
216 /* drop the frame and everything buffered except the first */
218 int drop = av_fifo_size(s->fifo)/sizeof(AVFrame*);
220 av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
223 av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
225 ret = write_to_fifo(s->fifo, tmp);
231 /* can output >= 1 frames */
232 for (i = 0; i < delta; i++) {
234 av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
236 /* duplicate the frame if needed */
237 if (!av_fifo_size(s->fifo) && i < delta - 1) {
238 AVFrame *dup = av_frame_clone(buf_out);
240 av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
242 ret = write_to_fifo(s->fifo, dup);
244 ret = AVERROR(ENOMEM);
247 av_frame_free(&buf_out);
255 buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
256 outlink->time_base) + s->frames_out;
258 if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {
267 ret = write_to_fifo(s->fifo, buf);
268 s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
273 static const AVFilterPad avfilter_vf_fps_inputs[] = {
276 .type = AVMEDIA_TYPE_VIDEO,
277 .filter_frame = filter_frame,
282 static const AVFilterPad avfilter_vf_fps_outputs[] = {
285 .type = AVMEDIA_TYPE_VIDEO,
286 .request_frame = request_frame,
287 .config_props = config_props
292 AVFilter avfilter_vf_fps = {
294 .description = NULL_IF_CONFIG_SMALL("Force constant framerate"),
299 .priv_size = sizeof(FPSContext),
300 .priv_class = &class,
302 .inputs = avfilter_vf_fps_inputs,
303 .outputs = avfilter_vf_fps_outputs,