| /* |
| * Copyright (c) 2012 Stefano Sabatini |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg 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. |
| * |
| * FFmpeg 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 FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file framestep filter, inspired on libmpcodecs/vf_framestep.c by |
| * Daniele Fornighieri <guru AT digitalfantasy it>. |
| */ |
| |
| #include "avfilter.h" |
| #include "internal.h" |
| #include "video.h" |
| |
| typedef struct { |
| int frame_step, frame_count, frame_selected; |
| } FrameStepContext; |
| |
| static av_cold int init(AVFilterContext *ctx, const char *args) |
| { |
| FrameStepContext *framestep = ctx->priv; |
| char *tailptr; |
| long int n = 1; |
| |
| if (args) { |
| n = strtol(args, &tailptr, 10); |
| if (*tailptr || n <= 0 || n >= INT_MAX) { |
| av_log(ctx, AV_LOG_ERROR, |
| "Invalid argument '%s', must be a positive integer <= INT_MAX\n", args); |
| return AVERROR(EINVAL); |
| } |
| } |
| |
| framestep->frame_step = n; |
| return 0; |
| } |
| |
| static int config_output_props(AVFilterLink *outlink) |
| { |
| AVFilterContext *ctx = outlink->src; |
| FrameStepContext *framestep = ctx->priv; |
| AVFilterLink *inlink = ctx->inputs[0]; |
| |
| outlink->frame_rate = |
| av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1}); |
| |
| av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n", |
| framestep->frame_step, |
| inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate), |
| outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate)); |
| return 0; |
| } |
| |
| static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *ref) |
| { |
| FrameStepContext *framestep = inlink->dst->priv; |
| |
| if (!(framestep->frame_count++ % framestep->frame_step)) { |
| framestep->frame_selected = 1; |
| return ff_filter_frame(inlink->dst->outputs[0], ref); |
| } else { |
| framestep->frame_selected = 0; |
| avfilter_unref_buffer(ref); |
| return 0; |
| } |
| } |
| |
| static int request_frame(AVFilterLink *outlink) |
| { |
| FrameStepContext *framestep = outlink->src->priv; |
| AVFilterLink *inlink = outlink->src->inputs[0]; |
| int ret; |
| |
| framestep->frame_selected = 0; |
| do { |
| ret = ff_request_frame(inlink); |
| } while (!framestep->frame_selected && ret >= 0); |
| |
| return ret; |
| } |
| |
| static const AVFilterPad framestep_inputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_VIDEO, |
| .get_video_buffer = ff_null_get_video_buffer, |
| .filter_frame = filter_frame, |
| }, |
| { NULL } |
| }; |
| |
| static const AVFilterPad framestep_outputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_VIDEO, |
| .config_props = config_output_props, |
| .request_frame = request_frame, |
| }, |
| { NULL } |
| }; |
| |
| AVFilter avfilter_vf_framestep = { |
| .name = "framestep", |
| .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."), |
| .init = init, |
| .priv_size = sizeof(FrameStepContext), |
| .inputs = framestep_inputs, |
| .outputs = framestep_outputs, |
| }; |