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/fifo.h"
25 #include "libavutil/mathematics.h"
26 #include "libavutil/opt.h"
27 #include "libavutil/parseutils.h"
33 typedef struct FPSContext {
36 AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
38 /* timestamps in input timebase */
39 int64_t first_pts; ///< pts of the first frame that arrived on this filter
40 int64_t pts; ///< pts of the first frame currently in the fifo
42 AVRational framerate; ///< target framerate
43 char *fps; ///< a string describing target framerate
46 int frames_in; ///< number of frames on input
47 int frames_out; ///< number of frames on output
48 int dup; ///< number of frames duplicated
49 int drop; ///< number of framed dropped
52 #define OFFSET(x) offsetof(FPSContext, x)
53 #define V AV_OPT_FLAG_VIDEO_PARAM
54 static const AVOption options[] = {
55 { "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
59 static const AVClass class = {
60 .class_name = "FPS filter",
61 .item_name = av_default_item_name,
63 .version = LIBAVUTIL_VERSION_INT,
66 static av_cold int init(AVFilterContext *ctx, const char *args)
68 FPSContext *s = ctx->priv;
72 av_opt_set_defaults(s);
74 if ((ret = av_set_options_string(s, args, "=", ":")) < 0) {
75 av_log(ctx, AV_LOG_ERROR, "Error parsing the options string %s.\n",
80 if ((ret = av_parse_video_rate(&s->framerate, s->fps)) < 0) {
81 av_log(ctx, AV_LOG_ERROR, "Error parsing framerate %s.\n", s->fps);
86 if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFilterBufferRef*))))
87 return AVERROR(ENOMEM);
89 av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
93 static void flush_fifo(AVFifoBuffer *fifo)
95 while (av_fifo_size(fifo)) {
96 AVFilterBufferRef *tmp;
97 av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
98 avfilter_unref_buffer(tmp);
102 static av_cold void uninit(AVFilterContext *ctx)
104 FPSContext *s = ctx->priv;
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;
121 s->pts = AV_NOPTS_VALUE;
126 static int request_frame(AVFilterLink *outlink)
128 AVFilterContext *ctx = outlink->src;
129 FPSContext *s = ctx->priv;
130 int frames_out = s->frames_out;
133 while (ret >= 0 && s->frames_out == frames_out)
134 ret = ff_request_frame(ctx->inputs[0]);
137 if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
139 for (i = 0; av_fifo_size(s->fifo); i++) {
140 AVFilterBufferRef *buf;
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;
146 if ((ret = ff_start_frame(outlink, buf)) < 0 ||
147 (ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
148 (ret = ff_end_frame(outlink)) < 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 end_frame(AVFilterLink *inlink)
175 AVFilterContext *ctx = inlink->dst;
176 FPSContext *s = ctx->priv;
177 AVFilterLink *outlink = ctx->outputs[0];
178 AVFilterBufferRef *buf = inlink->cur_buf;
182 inlink->cur_buf = NULL;
184 /* discard frames until we get the first timestamp */
185 if (s->pts == AV_NOPTS_VALUE) {
186 if (buf->pts != AV_NOPTS_VALUE) {
187 ret = write_to_fifo(s->fifo, buf);
191 s->first_pts = s->pts = buf->pts;
193 av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
195 avfilter_unref_buffer(buf);
201 /* now wait for the next timestamp */
202 if (buf->pts == AV_NOPTS_VALUE) {
203 return write_to_fifo(s->fifo, buf);
206 /* number of output frames */
207 delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
211 /* drop the frame and everything buffered except the first */
212 AVFilterBufferRef *tmp;
213 int drop = av_fifo_size(s->fifo)/sizeof(AVFilterBufferRef*);
215 av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
218 av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
220 ret = write_to_fifo(s->fifo, tmp);
222 avfilter_unref_buffer(buf);
226 /* can output >= 1 frames */
227 for (i = 0; i < delta; i++) {
228 AVFilterBufferRef *buf_out;
229 av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
231 /* duplicate the frame if needed */
232 if (!av_fifo_size(s->fifo) && i < delta - 1) {
233 AVFilterBufferRef *dup = avfilter_ref_buffer(buf_out, AV_PERM_READ);
235 av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
237 ret = write_to_fifo(s->fifo, dup);
239 ret = AVERROR(ENOMEM);
242 avfilter_unref_bufferp(&buf_out);
243 avfilter_unref_bufferp(&buf);
250 buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
251 outlink->time_base) + s->frames_out;
253 if ((ret = ff_start_frame(outlink, buf_out)) < 0 ||
254 (ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
255 (ret = ff_end_frame(outlink)) < 0) {
256 avfilter_unref_bufferp(&buf);
264 ret = write_to_fifo(s->fifo, buf);
265 s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
270 static int null_start_frame(AVFilterLink *link, AVFilterBufferRef *buf)
275 static int null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
280 AVFilter avfilter_vf_fps = {
282 .description = NULL_IF_CONFIG_SMALL("Force constant framerate"),
287 .priv_size = sizeof(FPSContext),
289 .inputs = (const AVFilterPad[]) {{ .name = "default",
290 .type = AVMEDIA_TYPE_VIDEO,
291 .start_frame = null_start_frame,
292 .draw_slice = null_draw_slice,
293 .end_frame = end_frame, },
295 .outputs = (const AVFilterPad[]) {{ .name = "default",
296 .type = AVMEDIA_TYPE_VIDEO,
297 .request_frame = request_frame,
298 .config_props = config_props},