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ffmpeg / libavfilter / vf_settb.c @ 2912e87a

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/*
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 * Copyright (c) 2010 Stefano Sabatini
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 *
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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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 * Set timebase for the output link.
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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/rational.h"
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#include "avfilter.h"
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#include "internal.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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    "intb",   /* input timebase */
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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_INTB,
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    VAR_VARS_NB
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};
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typedef struct {
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    char tb_expr[256];
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    double var_values[VAR_VARS_NB];
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} SetTBContext;
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static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    SetTBContext *settb = ctx->priv;
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    av_strlcpy(settb->tb_expr, "intb", sizeof(settb->tb_expr));
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    if (args)
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        sscanf(args, "%255[^:]", settb->tb_expr);
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    return 0;
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}
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static int config_output_props(AVFilterLink *outlink)
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{
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    AVFilterContext *ctx = outlink->src;
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    SetTBContext *settb = ctx->priv;
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    AVFilterLink *inlink = ctx->inputs[0];
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    AVRational time_base;
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    int ret;
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    double res;
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    settb->var_values[VAR_E]    = M_E;
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    settb->var_values[VAR_PHI]  = M_PHI;
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    settb->var_values[VAR_PI]   = M_PI;
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    settb->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
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    settb->var_values[VAR_INTB] = av_q2d(inlink->time_base);
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    outlink->w = inlink->w;
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    outlink->h = inlink->h;
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    if ((ret = av_expr_parse_and_eval(&res, settb->tb_expr, var_names, settb->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", settb->tb_expr);
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        return ret;
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    }
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    time_base = av_d2q(res, INT_MAX);
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    if (time_base.num <= 0 || time_base.den <= 0) {
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        av_log(ctx, AV_LOG_ERROR,
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               "Invalid non-positive values for the timebase num:%d or den:%d.\n",
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               time_base.num, time_base.den);
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        return AVERROR(EINVAL);
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    }
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    outlink->time_base = time_base;
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    av_log(outlink->src, AV_LOG_INFO, "tb:%d/%d -> tb:%d/%d\n",
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           inlink ->time_base.num, inlink ->time_base.den,
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           outlink->time_base.num, outlink->time_base.den);
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    return 0;
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}
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static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
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{
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    AVFilterContext *ctx = inlink->dst;
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    AVFilterLink *outlink = ctx->outputs[0];
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    AVFilterBufferRef *picref2 = picref;
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    if (av_cmp_q(inlink->time_base, outlink->time_base)) {
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        picref2 = avfilter_ref_buffer(picref, ~0);
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        picref2->pts = av_rescale_q(picref->pts, inlink->time_base, outlink->time_base);
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        av_log(ctx, AV_LOG_DEBUG, "tb:%d/%d pts:%"PRId64" -> tb:%d/%d pts:%"PRId64"\n",
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               inlink ->time_base.num, inlink ->time_base.den, picref ->pts,
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               outlink->time_base.num, outlink->time_base.den, picref2->pts);
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        avfilter_unref_buffer(picref);
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    }
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    avfilter_start_frame(outlink, picref2);
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}
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AVFilter avfilter_vf_settb = {
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    .name      = "settb",
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    .description = NULL_IF_CONFIG_SMALL("Set timebase for the output link."),
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    .init      = init,
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    .priv_size = sizeof(SetTBContext),
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    .inputs    = (AVFilterPad[]) {{ .name             = "default",
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                                    .type             = AVMEDIA_TYPE_VIDEO,
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                                    .get_video_buffer = avfilter_null_get_video_buffer,
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                                    .start_frame      = start_frame,
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                                    .end_frame        = avfilter_null_end_frame },
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                                  { .name = NULL }},
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    .outputs   = (AVFilterPad[]) {{ .name            = "default",
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                                    .type            = AVMEDIA_TYPE_VIDEO,
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                                    .config_props    = config_output_props, },
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                                  { .name = NULL}},
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};