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