ffmpeg/libavfilter/vf_field.c

   1 /*
   2  * Copyright (c) 2003 Rich Felker
   3  * Copyright (c) 2012 Stefano Sabatini
   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  * field filter, based on libmpcodecs/vf_field.c by Rich Felker
  25  */
  26
  27 #include "libavutil/opt.h"
  28 #include "libavutil/pixdesc.h"
  29 #include "avfilter.h"
  30 #include "internal.h"
  31
  32 enum FieldType { FIELD_TYPE_TOP = 0, FIELD_TYPE_BOTTOM };
  33
  34 typedef struct {
  35     const AVClass *class;
  36     enum FieldType type;
  37     int nb_planes;              ///< number of planes of the current format
  38 } FieldContext;
  39
  40 #define OFFSET(x) offsetof(FieldContext, x)
  41 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  42
  43 static const AVOption field_options[] = {
  44     {"type", "set field type (top or bottom)", OFFSET(type), AV_OPT_TYPE_INT, {.i64=FIELD_TYPE_TOP}, 0, 1, FLAGS, "field_type" },
  45     {"top",    "select top field",    0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_TOP},    INT_MIN, INT_MAX, FLAGS, "field_type"},
  46     {"bottom", "select bottom field", 0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "field_type"},
  47     {NULL}
  48 };
  49
  50 AVFILTER_DEFINE_CLASS(field);
  51
  52 static int config_props_output(AVFilterLink *outlink)
  53 {
  54     AVFilterContext *ctx = outlink->src;
  55     FieldContext *field = ctx->priv;
  56     AVFilterLink *inlink = ctx->inputs[0];
  57
  58     field->nb_planes = av_pix_fmt_count_planes(outlink->format);
  59
  60     outlink->w = inlink->w;
  61     outlink->h = (inlink->h + (field->type == FIELD_TYPE_TOP)) / 2;
  62
  63     av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d type:%s -> w:%d h:%d\n",
  64            inlink->w, inlink->h, field->type == FIELD_TYPE_BOTTOM ? "bottom" : "top",
  65            outlink->w, outlink->h);
  66     return 0;
  67 }
  68
  69 static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
  70 {
  71     FieldContext *field = inlink->dst->priv;
  72     AVFilterLink *outlink = inlink->dst->outputs[0];
  73     int i;
  74
  75     inpicref->height = outlink->h;
  76     inpicref->interlaced_frame = 0;
  77
  78     for (i = 0; i < field->nb_planes; i++) {
  79         if (field->type == FIELD_TYPE_BOTTOM)
  80             inpicref->data[i] = inpicref->data[i] + inpicref->linesize[i];
  81         inpicref->linesize[i] = 2 * inpicref->linesize[i];
  82     }
  83     return ff_filter_frame(outlink, inpicref);
  84 }
  85
  86 static const AVFilterPad field_inputs[] = {
  87     {
  88         .name         = "default",
  89         .type         = AVMEDIA_TYPE_VIDEO,
  90         .filter_frame = filter_frame,
  91     },
  92     { NULL }
  93 };
  94
  95 static const AVFilterPad field_outputs[] = {
  96     {
  97         .name         = "default",
  98         .type         = AVMEDIA_TYPE_VIDEO,
  99         .config_props = config_props_output,
 100     },
 101     { NULL }
 102 };
 103
 104 AVFilter ff_vf_field = {
 105     .name        = "field",
 106     .description = NULL_IF_CONFIG_SMALL("Extract a field from the input video."),
 107     .priv_size   = sizeof(FieldContext),
 108     .inputs      = field_inputs,
 109     .outputs     = field_outputs,
 110     .priv_class  = &field_class,
 111 };