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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->flags |= FF_LINK_FLAG_REQUEST_LOOP; | |
53 | outlink->frame_rate = | |
54 | av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1}); | |
55 | ||
56 | av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n", | |
57 | framestep->frame_step, | |
58 | inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate), | |
59 | outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate)); | |
60 | return 0; | |
61 | } | |
62 | ||
63 | static int filter_frame(AVFilterLink *inlink, AVFrame *ref) | |
64 | { | |
65 | FrameStepContext *framestep = inlink->dst->priv; | |
66 | ||
67 | if (!(inlink->frame_count % framestep->frame_step)) { | |
68 | return ff_filter_frame(inlink->dst->outputs[0], ref); | |
69 | } else { | |
70 | av_frame_free(&ref); | |
71 | return 0; | |
72 | } | |
73 | } | |
74 | ||
75 | static const AVFilterPad framestep_inputs[] = { | |
76 | { | |
77 | .name = "default", | |
78 | .type = AVMEDIA_TYPE_VIDEO, | |
79 | .filter_frame = filter_frame, | |
80 | }, | |
81 | { NULL } | |
82 | }; | |
83 | ||
84 | static const AVFilterPad framestep_outputs[] = { | |
85 | { | |
86 | .name = "default", | |
87 | .type = AVMEDIA_TYPE_VIDEO, | |
88 | .config_props = config_output_props, | |
89 | }, | |
90 | { NULL } | |
91 | }; | |
92 | ||
93 | AVFilter ff_vf_framestep = { | |
94 | .name = "framestep", | |
95 | .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."), | |
96 | .priv_size = sizeof(FrameStepContext), | |
97 | .priv_class = &framestep_class, | |
98 | .inputs = framestep_inputs, | |
99 | .outputs = framestep_outputs, | |
100 | .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, | |
101 | }; |