mirror of
https://github.com/FFmpeg/FFmpeg.git
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125 lines
3.6 KiB
C
125 lines
3.6 KiB
C
/*
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* Copyright (c) 2012 Stefano Sabatini
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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 framestep filter, inspired on libmpcodecs/vf_framestep.c by
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* Daniele Fornighieri <guru AT digitalfantasy it>.
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*/
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#include "avfilter.h"
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#include "internal.h"
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#include "video.h"
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typedef struct {
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int frame_step, frame_count, frame_selected;
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} FrameStepContext;
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static av_cold int init(AVFilterContext *ctx, const char *args)
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{
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FrameStepContext *framestep = ctx->priv;
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char *tailptr;
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long int n = 1;
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if (args) {
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n = strtol(args, &tailptr, 10);
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if (*tailptr || n <= 0 || n >= INT_MAX) {
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av_log(ctx, AV_LOG_ERROR,
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"Invalid argument '%s', must be a positive integer <= INT_MAX\n", args);
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return AVERROR(EINVAL);
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}
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}
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framestep->frame_step = n;
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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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FrameStepContext *framestep = ctx->priv;
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AVFilterLink *inlink = ctx->inputs[0];
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outlink->frame_rate =
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av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1});
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av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n",
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framestep->frame_step,
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inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate),
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outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate));
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return 0;
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}
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static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *ref)
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{
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FrameStepContext *framestep = inlink->dst->priv;
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if (!(framestep->frame_count++ % framestep->frame_step)) {
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framestep->frame_selected = 1;
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return ff_filter_frame(inlink->dst->outputs[0], ref);
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} else {
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framestep->frame_selected = 0;
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avfilter_unref_buffer(ref);
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return 0;
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}
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}
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static int request_frame(AVFilterLink *outlink)
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{
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FrameStepContext *framestep = outlink->src->priv;
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AVFilterLink *inlink = outlink->src->inputs[0];
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int ret;
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framestep->frame_selected = 0;
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do {
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ret = ff_request_frame(inlink);
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} while (!framestep->frame_selected && ret >= 0);
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return ret;
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}
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static const AVFilterPad framestep_inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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.get_video_buffer = ff_null_get_video_buffer,
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.filter_frame = filter_frame,
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},
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{ NULL }
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};
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static const AVFilterPad framestep_outputs[] = {
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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_output_props,
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.request_frame = request_frame,
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},
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{ NULL }
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};
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AVFilter avfilter_vf_framestep = {
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.name = "framestep",
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.description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."),
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.init = init,
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.priv_size = sizeof(FrameStepContext),
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.inputs = framestep_inputs,
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.outputs = framestep_outputs,
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};
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