Add video filter to manipulate aspect ratio
[libav.git] / libavfilter / vf_aspect.c
1 /*
2 * Aspect ratio modification video filter
3 * Copyright (c) 2010 Bobby Bingham
4
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file libavfilter/vf_aspect.c
24 * aspect ratio modification video filter
25 */
26
27 #include "avfilter.h"
28
29 typedef struct {
30 AVRational aspect;
31 } AspectContext;
32
33 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
34 {
35 AspectContext *aspect = ctx->priv;
36 double ratio;
37 int64_t gcd;
38
39 if(args) {
40 if(sscanf(args, "%d:%d", &aspect->aspect.num, &aspect->aspect.den) < 2) {
41 if(sscanf(args, "%lf", &ratio) < 1)
42 return -1;
43 aspect->aspect = av_d2q(ratio, 100);
44 } else {
45 gcd = av_gcd(FFABS(aspect->aspect.num), FFABS(aspect->aspect.den));
46 if(gcd) {
47 aspect->aspect.num /= gcd;
48 aspect->aspect.den /= gcd;
49 }
50 }
51 }
52
53 if(aspect->aspect.den == 0)
54 aspect->aspect = (AVRational) {0, 1};
55
56 return 0;
57 }
58
59
60 static AVFilterPicRef *get_video_buffer(AVFilterLink *link, int perms,
61 int w, int h)
62 {
63 return avfilter_get_video_buffer(link->dst->outputs[0], perms, w, h);
64 }
65
66 static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
67 {
68 AspectContext *aspect = link->dst->priv;
69
70 picref->pixel_aspect = aspect->aspect;
71 avfilter_start_frame(link->dst->outputs[0], picref);
72 }
73
74 static void end_frame(AVFilterLink *link)
75 {
76 avfilter_end_frame(link->dst->outputs[0]);
77 }
78
79 #if CONFIG_ASPECT_FILTER
80 /* for aspect filter, convert from frame aspect ratio to pixel aspect ratio */
81 static int frameaspect_config_props(AVFilterLink *inlink)
82 {
83 AspectContext *aspect = inlink->dst->priv;
84
85 av_reduce(&aspect->aspect.num, &aspect->aspect.den,
86 aspect->aspect.num * inlink->h,
87 aspect->aspect.den * inlink->w, 100);
88
89 return 0;
90 }
91
92 AVFilter avfilter_vf_aspect = {
93 .name = "aspect",
94 .description = NULL_IF_CONFIG_SMALL("Set the frame aspect ratio."),
95
96 .init = init,
97
98 .priv_size = sizeof(AspectContext),
99
100 .inputs = (AVFilterPad[]) {{ .name = "default",
101 .type = CODEC_TYPE_VIDEO,
102 .config_props = frameaspect_config_props,
103 .get_video_buffer = get_video_buffer,
104 .start_frame = start_frame,
105 .end_frame = end_frame },
106 { .name = NULL}},
107
108 .outputs = (AVFilterPad[]) {{ .name = "default",
109 .type = CODEC_TYPE_VIDEO, },
110 { .name = NULL}},
111 };
112 #endif /* CONFIG_ASPECT_FILTER */
113
114 #if CONFIG_PIXELASPECT_FILTER
115 AVFilter avfilter_vf_pixelaspect = {
116 .name = "pixelaspect",
117 .description = NULL_IF_CONFIG_SMALL("Set the pixel aspect ratio."),
118
119 .init = init,
120
121 .priv_size = sizeof(AspectContext),
122
123 .inputs = (AVFilterPad[]) {{ .name = "default",
124 .type = CODEC_TYPE_VIDEO,
125 .get_video_buffer = get_video_buffer,
126 .start_frame = start_frame,
127 .end_frame = end_frame },
128 { .name = NULL}},
129
130 .outputs = (AVFilterPad[]) {{ .name = "default",
131 .type = CODEC_TYPE_VIDEO, },
132 { .name = NULL}},
133 };
134 #endif /* CONFIG_PIXELASPECT_FILTER */
135