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"
31 typedef struct FPSContext {
34 AVFifoBuffer *fifo; ///< store frames until we get two successive timestamps
36 /* timestamps in input timebase */
37 int64_t first_pts; ///< pts of the first frame that arrived on this filter
38 int64_t pts; ///< pts of the first frame currently in the fifo
40 AVRational framerate; ///< target framerate
41 char *fps; ///< a string describing target framerate
44 int frames_in; ///< number of frames on input
45 int frames_out; ///< number of frames on output
46 int dup; ///< number of frames duplicated
47 int drop; ///< number of framed dropped
50 #define OFFSET(x) offsetof(FPSContext, x)
51 #define V AV_OPT_FLAG_VIDEO_PARAM
52 static const AVOption options[] = {
53 { "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
57 static const AVClass class = {
58 .class_name = "FPS filter",
59 .item_name = av_default_item_name,
61 .version = LIBAVUTIL_VERSION_INT,
64 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
66 FPSContext *s = ctx->priv;
70 av_opt_set_defaults(s);
72 if ((ret = av_set_options_string(s, args, "=", ":")) < 0) {
73 av_log(ctx, AV_LOG_ERROR, "Error parsing the options string %s.\n",
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);
84 if (!(s->fifo = av_fifo_alloc(2*sizeof(AVFilterBufferRef*))))
85 return AVERROR(ENOMEM);
87 av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
91 static void flush_fifo(AVFifoBuffer *fifo)
93 while (av_fifo_size(fifo)) {
94 AVFilterBufferRef *tmp;
95 av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
96 avfilter_unref_buffer(tmp);
100 static av_cold void uninit(AVFilterContext *ctx)
102 FPSContext *s = ctx->priv;
105 av_fifo_free(s->fifo);
108 av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
109 "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
112 static int config_props(AVFilterLink* link)
114 FPSContext *s = link->src->priv;
116 link->time_base = (AVRational){ s->framerate.den, s->framerate.num };
117 link->w = link->src->inputs[0]->w;
118 link->h = link->src->inputs[0]->h;
119 s->pts = AV_NOPTS_VALUE;
124 static int request_frame(AVFilterLink *outlink)
126 AVFilterContext *ctx = outlink->src;
127 FPSContext *s = ctx->priv;
128 int frames_out = s->frames_out;
131 while (ret >= 0 && s->frames_out == frames_out)
132 ret = avfilter_request_frame(ctx->inputs[0]);
135 if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
137 for (i = 0; av_fifo_size(s->fifo); i++) {
138 AVFilterBufferRef *buf;
140 av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);
141 buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
142 outlink->time_base) + s->frames_out;
144 avfilter_start_frame(outlink, buf);
145 avfilter_draw_slice(outlink, 0, outlink->h, 1);
146 avfilter_end_frame(outlink);
155 static int write_to_fifo(AVFifoBuffer *fifo, AVFilterBufferRef *buf)
159 if (!av_fifo_space(fifo) &&
160 (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo))))
163 av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
167 static void end_frame(AVFilterLink *inlink)
169 AVFilterContext *ctx = inlink->dst;
170 FPSContext *s = ctx->priv;
171 AVFilterLink *outlink = ctx->outputs[0];
172 AVFilterBufferRef *buf = inlink->cur_buf;
177 /* discard frames until we get the first timestamp */
178 if (s->pts == AV_NOPTS_VALUE) {
179 if (buf->pts != AV_NOPTS_VALUE) {
180 write_to_fifo(s->fifo, buf);
181 s->first_pts = s->pts = buf->pts;
183 av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
185 avfilter_unref_buffer(buf);
191 /* now wait for the next timestamp */
192 if (buf->pts == AV_NOPTS_VALUE) {
193 write_to_fifo(s->fifo, buf);
197 /* number of output frames */
198 delta = av_rescale_q(buf->pts - s->pts, inlink->time_base,
202 /* drop the frame and everything buffered except the first */
203 AVFilterBufferRef *tmp;
204 int drop = av_fifo_size(s->fifo)/sizeof(AVFilterBufferRef*);
206 av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
209 av_fifo_generic_read(s->fifo, &tmp, sizeof(tmp), NULL);
211 write_to_fifo(s->fifo, tmp);
213 avfilter_unref_buffer(buf);
217 /* can output >= 1 frames */
218 for (i = 0; i < delta; i++) {
219 AVFilterBufferRef *buf_out;
220 av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
222 /* duplicate the frame if needed */
223 if (!av_fifo_size(s->fifo) && i < delta - 1) {
224 av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
225 write_to_fifo(s->fifo, avfilter_ref_buffer(buf_out, AV_PERM_READ));
229 buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
230 outlink->time_base) + s->frames_out;
232 avfilter_start_frame(outlink, buf_out);
233 avfilter_draw_slice(outlink, 0, outlink->h, 1);
234 avfilter_end_frame(outlink);
239 write_to_fifo(s->fifo, buf);
240 s->pts = s->first_pts + av_rescale_q(s->frames_out, outlink->time_base, inlink->time_base);
243 static void null_start_frame(AVFilterLink *link, AVFilterBufferRef *buf)
247 static void null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
251 AVFilter avfilter_vf_fps = {
253 .description = NULL_IF_CONFIG_SMALL("Force constant framerate"),
258 .priv_size = sizeof(FPSContext),
260 .inputs = (AVFilterPad[]) {{ .name = "default",
261 .type = AVMEDIA_TYPE_VIDEO,
262 .start_frame = null_start_frame,
263 .draw_slice = null_draw_slice,
264 .end_frame = end_frame, },
266 .outputs = (AVFilterPad[]) {{ .name = "default",
267 .type = AVMEDIA_TYPE_VIDEO,
268 .request_frame = request_frame,
269 .config_props = config_props},