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FFmpeg/libavfilter/vf_field.c
Andreas Rheinhardt 8be701d9f7 avfilter/avfilter: Add numbers of (in|out)pads directly to AVFilter
Up until now, an AVFilter's lists of input and output AVFilterPads
were terminated by a sentinel and the only way to get the length
of these lists was by using avfilter_pad_count(). This has two
drawbacks: first, sizeof(AVFilterPad) is not negligible
(i.e. 64B on 64bit systems); second, getting the size involves
a function call instead of just reading the data.

This commit therefore changes this. The sentinels are removed and new
private fields nb_inputs and nb_outputs are added to AVFilter that
contain the number of elements of the respective AVFilterPad array.

Given that AVFilter.(in|out)puts are the only arrays of zero-terminated
AVFilterPads an API user has access to (AVFilterContext.(in|out)put_pads
are not zero-terminated and they already have a size field) the argument
to avfilter_pad_count() is always one of these lists, so it just has to
find the filter the list belongs to and read said number. This is slower
than before, but a replacement function that just reads the internal numbers
that users are expected to switch to will be added soon; and furthermore,
avfilter_pad_count() is probably never called in hot loops anyway.

This saves about 49KiB from the binary; notice that these sentinels are
not in .bss despite being zeroed: they are in .data.rel.ro due to the
non-sentinels.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2021-08-20 12:53:58 +02:00

110 lines
3.5 KiB
C

/*
* Copyright (c) 2003 Rich Felker
* Copyright (c) 2012 Stefano Sabatini
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* field filter, based on libmpcodecs/vf_field.c by Rich Felker
*/
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "avfilter.h"
#include "internal.h"
enum FieldType { FIELD_TYPE_TOP = 0, FIELD_TYPE_BOTTOM };
typedef struct FieldContext {
const AVClass *class;
int type; ///< FieldType
int nb_planes; ///< number of planes of the current format
} FieldContext;
#define OFFSET(x) offsetof(FieldContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
static const AVOption field_options[] = {
{"type", "set field type (top or bottom)", OFFSET(type), AV_OPT_TYPE_INT, {.i64=FIELD_TYPE_TOP}, 0, 1, FLAGS, "field_type" },
{"top", "select top field", 0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_TOP}, INT_MIN, INT_MAX, FLAGS, "field_type"},
{"bottom", "select bottom field", 0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "field_type"},
{NULL}
};
AVFILTER_DEFINE_CLASS(field);
static int config_props_output(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
FieldContext *field = ctx->priv;
AVFilterLink *inlink = ctx->inputs[0];
field->nb_planes = av_pix_fmt_count_planes(outlink->format);
outlink->w = inlink->w;
outlink->h = (inlink->h + (field->type == FIELD_TYPE_TOP)) / 2;
av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d type:%s -> w:%d h:%d\n",
inlink->w, inlink->h, field->type == FIELD_TYPE_BOTTOM ? "bottom" : "top",
outlink->w, outlink->h);
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
{
FieldContext *field = inlink->dst->priv;
AVFilterLink *outlink = inlink->dst->outputs[0];
int i;
inpicref->height = outlink->h;
inpicref->interlaced_frame = 0;
for (i = 0; i < field->nb_planes; i++) {
if (field->type == FIELD_TYPE_BOTTOM)
inpicref->data[i] = inpicref->data[i] + inpicref->linesize[i];
inpicref->linesize[i] = 2 * inpicref->linesize[i];
}
return ff_filter_frame(outlink, inpicref);
}
static const AVFilterPad field_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
};
static const AVFilterPad field_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_props_output,
},
};
const AVFilter ff_vf_field = {
.name = "field",
.description = NULL_IF_CONFIG_SMALL("Extract a field from the input video."),
.priv_size = sizeof(FieldContext),
FILTER_INPUTS(field_inputs),
FILTER_OUTPUTS(field_outputs),
.priv_class = &field_class,
};