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/*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* null video source
*/
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/mathematics.h"
#include "libavutil/parseutils.h"
#include "avfilter.h"
static const char *var_names[] = {
"E",
"PHI",
"PI",
"AVTB", /* default timebase 1/AV_TIME_BASE */
NULL
};
enum var_name {
VAR_E,
VAR_PHI,
VAR_PI,
VAR_AVTB,
VAR_VARS_NB
};
typedef struct {
int w, h;
char tb_expr[256];
double var_values[VAR_VARS_NB];
} NullContext;
static int init(AVFilterContext *ctx, const char *args, void *opaque)
{
NullContext *priv = ctx->priv;
priv->w = 352;
priv->h = 288;
av_strlcpy(priv->tb_expr, "AVTB", sizeof(priv->tb_expr));
if (args)
sscanf(args, "%d:%d:%255[^:]", &priv->w, &priv->h, priv->tb_expr);
if (priv->w <= 0 || priv->h <= 0) {
av_log(ctx, AV_LOG_ERROR, "Non-positive size values are not acceptable.\n");
return AVERROR(EINVAL);
}
return 0;
}
static int config_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
NullContext *priv = ctx->priv;
AVRational tb;
int ret;
double res;
priv->var_values[VAR_E] = M_E;
priv->var_values[VAR_PHI] = M_PHI;
priv->var_values[VAR_PI] = M_PI;
priv->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
if ((ret = av_expr_parse_and_eval(&res, priv->tb_expr, var_names, priv->var_values,
NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for timebase.\n", priv->tb_expr);
return ret;
}
tb = av_d2q(res, INT_MAX);
if (tb.num <= 0 || tb.den <= 0) {
av_log(ctx, AV_LOG_ERROR,
"Invalid non-positive value for the timebase %d/%d.\n",
tb.num, tb.den);
return AVERROR(EINVAL);
}
outlink->w = priv->w;
outlink->h = priv->h;
outlink->time_base = tb;
av_log(outlink->src, AV_LOG_INFO, "w:%d h:%d tb:%d/%d\n", priv->w, priv->h,
tb.num, tb.den);
return 0;
}
static int request_frame(AVFilterLink *link)
{
return -1;
}
AVFilter avfilter_vsrc_nullsrc = {
.name = "nullsrc",
.description = NULL_IF_CONFIG_SMALL("Null video source, never return images."),
.init = init,
.priv_size = sizeof(NullContext),
.inputs = (AVFilterPad[]) {{ .name = NULL}},
.outputs = (AVFilterPad[]) {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_props,
.request_frame = request_frame,
},
{ .name = NULL}
},
};
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