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