blob: 8102e7c719552d0395aa51c15eb3d8e96b4d1baa
| 1 | /* |
| 2 | * Copyright (c) 2012 Stefano Sabatini |
| 3 | * |
| 4 | * This file is part of FFmpeg. |
| 5 | * |
| 6 | * FFmpeg is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * FFmpeg is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with FFmpeg; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | */ |
| 20 | |
| 21 | /** |
| 22 | * @file framestep filter, inspired on libmpcodecs/vf_framestep.c by |
| 23 | * Daniele Fornighieri <guru AT digitalfantasy it>. |
| 24 | */ |
| 25 | |
| 26 | #include "libavutil/opt.h" |
| 27 | #include "avfilter.h" |
| 28 | #include "internal.h" |
| 29 | #include "video.h" |
| 30 | |
| 31 | typedef struct NullContext { |
| 32 | const AVClass *class; |
| 33 | int frame_step; |
| 34 | } FrameStepContext; |
| 35 | |
| 36 | #define OFFSET(x) offsetof(FrameStepContext, x) |
| 37 | #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM |
| 38 | |
| 39 | static const AVOption framestep_options[] = { |
| 40 | { "step", "set frame step", OFFSET(frame_step), AV_OPT_TYPE_INT, {.i64=1}, 1, INT_MAX, FLAGS}, |
| 41 | { NULL }, |
| 42 | }; |
| 43 | |
| 44 | AVFILTER_DEFINE_CLASS(framestep); |
| 45 | |
| 46 | static int config_output_props(AVFilterLink *outlink) |
| 47 | { |
| 48 | AVFilterContext *ctx = outlink->src; |
| 49 | FrameStepContext *framestep = ctx->priv; |
| 50 | AVFilterLink *inlink = ctx->inputs[0]; |
| 51 | |
| 52 | outlink->frame_rate = |
| 53 | av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1}); |
| 54 | |
| 55 | av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n", |
| 56 | framestep->frame_step, |
| 57 | inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate), |
| 58 | outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate)); |
| 59 | return 0; |
| 60 | } |
| 61 | |
| 62 | static int filter_frame(AVFilterLink *inlink, AVFrame *ref) |
| 63 | { |
| 64 | FrameStepContext *framestep = inlink->dst->priv; |
| 65 | |
| 66 | if (!(inlink->frame_count_out % framestep->frame_step)) { |
| 67 | return ff_filter_frame(inlink->dst->outputs[0], ref); |
| 68 | } else { |
| 69 | av_frame_free(&ref); |
| 70 | return 0; |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | static const AVFilterPad framestep_inputs[] = { |
| 75 | { |
| 76 | .name = "default", |
| 77 | .type = AVMEDIA_TYPE_VIDEO, |
| 78 | .filter_frame = filter_frame, |
| 79 | }, |
| 80 | { NULL } |
| 81 | }; |
| 82 | |
| 83 | static const AVFilterPad framestep_outputs[] = { |
| 84 | { |
| 85 | .name = "default", |
| 86 | .type = AVMEDIA_TYPE_VIDEO, |
| 87 | .config_props = config_output_props, |
| 88 | }, |
| 89 | { NULL } |
| 90 | }; |
| 91 | |
| 92 | AVFilter ff_vf_framestep = { |
| 93 | .name = "framestep", |
| 94 | .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."), |
| 95 | .priv_size = sizeof(FrameStepContext), |
| 96 | .priv_class = &framestep_class, |
| 97 | .inputs = framestep_inputs, |
| 98 | .outputs = framestep_outputs, |
| 99 | .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, |
| 100 | }; |
| 101 |