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
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"
34 typedef struct FPSContext {
37 AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
39 /* timestamps in input timebase */
40 int64_t first_pts; ///< pts of the first frame that arrived on this filter
41 int64_t pts; ///< pts of the first frame currently in the fifo
43 AVRational framerate; ///< target framerate
44 char *fps; ///< a string describing target framerate
47 int frames_in; ///< number of frames on input
48 int frames_out; ///< number of frames on output
49 int dup; ///< number of frames duplicated
50 int drop; ///< number of framed dropped
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 },
60 static const AVClass class = {
61 .class_name = "FPS filter",
62 .item_name = av_default_item_name,
64 .version = LIBAVUTIL_VERSION_INT,
67 static av_cold int init(AVFilterContext *ctx, const char *args)
69 FPSContext *s = ctx->priv;
73 av_opt_set_defaults(s);
75 if ((ret = av_set_options_string(s, args, "=", ":")) < 0) {
76 av_log(ctx, AV_LOG_ERROR, "Error parsing the options string %s.\n",
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);
87 if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFilterBufferRef*))))
88 return AVERROR(ENOMEM);
90 av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
94 static void flush_fifo(AVFifoBuffer *fifo)
96 while (av_fifo_size(fifo)) {
97 AVFilterBufferRef *tmp;
98 av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
99 avfilter_unref_buffer(tmp);
103 static av_cold void uninit(AVFilterContext *ctx)
105 FPSContext *s = ctx->priv;
107 s->drop += av_fifo_size(s->fifo) / sizeof(AVFilterBufferRef*);
109 av_fifo_free(s->fifo);
112 av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
113 "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
116 static int config_props(AVFilterLink* link)
118 FPSContext *s = link->src->priv;
120 link->time_base = (AVRational){ s->framerate.den, s->framerate.num };
121 link->w = link->src->inputs[0]->w;
122 link->h = link->src->inputs[0]->h;
123 s->pts = AV_NOPTS_VALUE;
128 static int request_frame(AVFilterLink *outlink)
130 AVFilterContext *ctx = outlink->src;
131 FPSContext *s = ctx->priv;
132 int frames_out = s->frames_out;
135 while (ret >= 0 && s->frames_out == frames_out)
136 ret = ff_request_frame(ctx->inputs[0]);
139 if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
141 for (i = 0; av_fifo_size(s->fifo); i++) {
142 AVFilterBufferRef *buf;
144 av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
145 buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
146 outlink->time_base) + s->frames_out;
148 if ((ret = ff_filter_frame(outlink, buf)) < 0)
159 static int write_to_fifo(AVFifoBuffer *fifo, AVFilterBufferRef *buf)
163 if (!av_fifo_space(fifo) &&
164 (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {
165 avfilter_unref_bufferp(&buf);
169 av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
173 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *buf)
175 AVFilterContext *ctx = inlink->dst;
176 FPSContext *s = ctx->priv;
177 AVFilterLink *outlink = ctx->outputs[0];
182 /* discard frames until we get the first timestamp */
183 if (s->pts == AV_NOPTS_VALUE) {
184 if (buf->pts != AV_NOPTS_VALUE) {
185 ret = write_to_fifo(s->fifo, buf);
189 s->first_pts = s->pts = buf->pts;
191 av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
193 avfilter_unref_buffer(buf);
199 /* now wait for the next timestamp */
200 if (buf->pts == AV_NOPTS_VALUE) {
201 return write_to_fifo(s->fifo, buf);
204 /* number of output frames */
205 delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
209 /* drop the frame and everything buffered except the first */
210 AVFilterBufferRef *tmp;
211 int drop = av_fifo_size(s->fifo)/sizeof(AVFilterBufferRef*);
213 av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
216 av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
218 ret = write_to_fifo(s->fifo, tmp);
220 avfilter_unref_buffer(buf);
224 /* can output >= 1 frames */
225 for (i = 0; i < delta; i++) {
226 AVFilterBufferRef *buf_out;
227 av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
229 /* duplicate the frame if needed */
230 if (!av_fifo_size(s->fifo) && i < delta - 1) {
231 AVFilterBufferRef *dup = avfilter_ref_buffer(buf_out, AV_PERM_READ);
233 av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
235 ret = write_to_fifo(s->fifo, dup);
237 ret = AVERROR(ENOMEM);
240 avfilter_unref_bufferp(&buf_out);
241 avfilter_unref_bufferp(&buf);
248 buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
249 outlink->time_base) + s->frames_out;
251 if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {
252 avfilter_unref_bufferp(&buf);
260 ret = write_to_fifo(s->fifo, buf);
261 s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
266 static const AVFilterPad avfilter_vf_fps_inputs[] = {
269 .type = AVMEDIA_TYPE_VIDEO,
270 .filter_frame = filter_frame,
275 static const AVFilterPad avfilter_vf_fps_outputs[] = {
278 .type = AVMEDIA_TYPE_VIDEO,
279 .request_frame = request_frame,
280 .config_props = config_props
285 AVFilter avfilter_vf_fps = {
287 .description = NULL_IF_CONFIG_SMALL("Force constant framerate"),
292 .priv_size = sizeof(FPSContext),
294 .inputs = avfilter_vf_fps_inputs,
295 .outputs = avfilter_vf_fps_outputs,