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
24 #include "libavutil/avstring.h"
25 #include "libavutil/eval.h"
26 #include "libavutil/mathematics.h"
27 #include "libavutil/parseutils.h"
32 static const char *const var_names[] = {
36 "AVTB", /* default timebase 1/AV_TIME_BASE */
51 double var_values[VAR_VARS_NB];
54 static int init(AVFilterContext *ctx, const char *args)
56 NullContext *priv = ctx->priv;
60 av_strlcpy(priv->tb_expr, "AVTB", sizeof(priv->tb_expr));
63 sscanf(args, "%d:%d:%255[^:]", &priv->w, &priv->h, priv->tb_expr);
65 if (priv->w <= 0 || priv->h <= 0) {
66 av_log(ctx, AV_LOG_ERROR, "Non-positive size values are not acceptable.\n");
67 return AVERROR(EINVAL);
73 static int config_props(AVFilterLink *outlink)
75 AVFilterContext *ctx = outlink->src;
76 NullContext *priv = ctx->priv;
81 priv->var_values[VAR_E] = M_E;
82 priv->var_values[VAR_PHI] = M_PHI;
83 priv->var_values[VAR_PI] = M_PI;
84 priv->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
86 if ((ret = av_expr_parse_and_eval(&res, priv->tb_expr, var_names, priv->var_values,
87 NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
88 av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for timebase.\n", priv->tb_expr);
91 tb = av_d2q(res, INT_MAX);
92 if (tb.num <= 0 || tb.den <= 0) {
93 av_log(ctx, AV_LOG_ERROR,
94 "Invalid non-positive value for the timebase %d/%d.\n",
96 return AVERROR(EINVAL);
100 outlink->h = priv->h;
101 outlink->time_base = tb;
103 av_log(outlink->src, AV_LOG_VERBOSE, "w:%d h:%d tb:%d/%d\n", priv->w, priv->h,
109 static int request_frame(AVFilterLink *link)
114 AVFilter avfilter_vsrc_nullsrc = {
116 .description = NULL_IF_CONFIG_SMALL("Null video source, never return images."),
119 .priv_size = sizeof(NullContext),
121 .inputs = (AVFilterPad[]) {{ .name = NULL}},
123 .outputs = (AVFilterPad[]) {
126 .type = AVMEDIA_TYPE_VIDEO,
127 .config_props = config_props,
128 .request_frame = request_frame,