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
24 * aspect ratio modification video filter
25 */
26
27#include "avfilter.h"
28
29typedef struct {
30    AVRational aspect;
31} AspectContext;
32
33static 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
59static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
60{
61    AspectContext *aspect = link->dst->priv;
62
63    picref->pixel_aspect = aspect->aspect;
64    avfilter_start_frame(link->dst->outputs[0], picref);
65}
66
67#if CONFIG_ASPECT_FILTER
68/* for aspect filter, convert from frame aspect ratio to pixel aspect ratio */
69static int frameaspect_config_props(AVFilterLink *inlink)
70{
71    AspectContext *aspect = inlink->dst->priv;
72
73    av_reduce(&aspect->aspect.num, &aspect->aspect.den,
74               aspect->aspect.num * inlink->h,
75               aspect->aspect.den * inlink->w, 100);
76
77    return 0;
78}
79
80AVFilter avfilter_vf_aspect = {
81    .name      = "aspect",
82    .description = NULL_IF_CONFIG_SMALL("Set the frame aspect ratio."),
83
84    .init      = init,
85
86    .priv_size = sizeof(AspectContext),
87
88    .inputs    = (AVFilterPad[]) {{ .name             = "default",
89                                    .type             = AVMEDIA_TYPE_VIDEO,
90                                    .config_props     = frameaspect_config_props,
91                                    .get_video_buffer = avfilter_null_get_video_buffer,
92                                    .start_frame      = start_frame,
93                                    .end_frame        = avfilter_null_end_frame },
94                                  { .name = NULL}},
95
96    .outputs   = (AVFilterPad[]) {{ .name             = "default",
97                                    .type             = AVMEDIA_TYPE_VIDEO, },
98                                  { .name = NULL}},
99};
100#endif /* CONFIG_ASPECT_FILTER */
101
102#if CONFIG_PIXELASPECT_FILTER
103AVFilter avfilter_vf_pixelaspect = {
104    .name      = "pixelaspect",
105    .description = NULL_IF_CONFIG_SMALL("Set the pixel aspect ratio."),
106
107    .init      = init,
108
109    .priv_size = sizeof(AspectContext),
110
111    .inputs    = (AVFilterPad[]) {{ .name             = "default",
112                                    .type             = AVMEDIA_TYPE_VIDEO,
113                                    .get_video_buffer = avfilter_null_get_video_buffer,
114                                    .start_frame      = start_frame,
115                                    .end_frame        = avfilter_null_end_frame },
116                                  { .name = NULL}},
117
118    .outputs   = (AVFilterPad[]) {{ .name             = "default",
119                                    .type             = AVMEDIA_TYPE_VIDEO, },
120                                  { .name = NULL}},
121};
122#endif /* CONFIG_PIXELASPECT_FILTER */
123
124