[FFmpeg-devel] [PATCH] lavfi: add field filter
Clément Bœsch
ubitux at gmail.com
Tue Oct 30 21:37:52 CET 2012
On Tue, Oct 30, 2012 at 01:31:14PM +0100, Stefano Sabatini wrote:
> The filter is a port of libmpcodecs/vf_field.c, since there is no common
> code I relicensed it as LGPL, while keeping the original author
> copyright.
>
> TODO: bump lavfi minor, update Changelog
> ---
> doc/filters.texi | 25 ++++++++
> libavfilter/Makefile | 1 +
> libavfilter/allfilters.c | 1 +
> libavfilter/vf_field.c | 145 +++++++++++++++++++++++++++++++++++++++++++++
> tests/fate/avfilter.mak | 1 +
> tests/lavfi-regression.sh | 1 +
> tests/ref/lavfi/field | 83 ++++++++++++++++++++++++++
> 7 files changed, 257 insertions(+), 0 deletions(-)
> create mode 100644 libavfilter/vf_field.c
> create mode 100644 tests/ref/lavfi/field
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 0e77914..215c12a 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -2115,6 +2115,31 @@ fade=in:5:20
> fade=in:0:25:alpha=1
> @end example
>
> + at section field
> +
> +Extract a single field from an interlaced image using stride
> +arithmetic to avoid wasting CPU time. The output frames are marked as
> +non-interlaced.
> +
> +This filter accepts the following named options:
> + at table @option
> + at item type
> +Specify whether to extract the top (if the value is @code{0} or
> + at code{top}) or the bottom field (if the value is @code{1} or
> + at code{bottom}.
missing closing ')'
> + at end table
> +
> +If the option key is not specified, the first value specifies the
> +type. For example:
> + at example
> +field=type=bottom
> + at end example
> +
> +is equivalent to:
> + at example
> +field=1
> + at end example
> +
I'm still wondering about the kind of use-case for this filter though...
> @section fieldorder
>
> Transform the field order of the input video.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 3618f10..0da0645 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -98,6 +98,7 @@ OBJS-$(CONFIG_DRAWBOX_FILTER) += vf_drawbox.o
> OBJS-$(CONFIG_DRAWTEXT_FILTER) += vf_drawtext.o
> OBJS-$(CONFIG_EDGEDETECT_FILTER) += vf_edgedetect.o
> OBJS-$(CONFIG_FADE_FILTER) += vf_fade.o
> +OBJS-$(CONFIG_FIELD_FILTER) += vf_field.o
> OBJS-$(CONFIG_FIELDORDER_FILTER) += vf_fieldorder.o
> OBJS-$(CONFIG_FIFO_FILTER) += fifo.o
> OBJS-$(CONFIG_FORMAT_FILTER) += vf_format.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 348f369..fef40e9 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -90,6 +90,7 @@ void avfilter_register_all(void)
> REGISTER_FILTER (DRAWTEXT, drawtext, vf);
> REGISTER_FILTER (EDGEDETECT, edgedetect, vf);
> REGISTER_FILTER (FADE, fade, vf);
> + REGISTER_FILTER (FIELD, field, vf);
> REGISTER_FILTER (FIELDORDER, fieldorder, vf);
> REGISTER_FILTER (FIFO, fifo, vf);
> REGISTER_FILTER (FORMAT, format, vf);
> diff --git a/libavfilter/vf_field.c b/libavfilter/vf_field.c
> new file mode 100644
> index 0000000..db55b99
> --- /dev/null
> +++ b/libavfilter/vf_field.c
> @@ -0,0 +1,145 @@
> +/*
> + * 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
missing \n (I think Paul pointed that out already)
> + */
> +
> +#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 {
> + const AVClass *class;
> + enum FieldType type;
> + 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 av_cold int init(AVFilterContext *ctx, const char *args)
> +{
> + FieldContext *field = ctx->priv;
> + static const char *shorthand[] = { "type", NULL };
> +
> + field->class = &field_class;
> + av_opt_set_defaults(field);
> +
> + return av_opt_set_from_string(field, args, shorthand, "=", ":");
> +}
> +
> +static int config_props_output(AVFilterLink *outlink)
> +{
> + AVFilterContext *ctx = outlink->src;
> + FieldContext *field = ctx->priv;
> + AVFilterLink *inlink = ctx->inputs[0];
> + const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
> + int i;
> +
> + for (i = 0; i < desc->nb_components; i++)
> + field->nb_planes = FFMAX(field->nb_planes, desc->comp[i].plane);
> + field->nb_planes++;
> +
> + outlink->w = inlink->w;
> + outlink->h = inlink->h/2;
If we have an odd height, won't this drop one of the line?
> +
> + 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 start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
> +{
> + FieldContext *field = inlink->dst->priv;
> + const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
> + AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);
> + int i;
> +
> + if (!outpicref)
> + return AVERROR(ENOMEM);
> + outpicref->video->h = inpicref->video->h/2;
> + outpicref->video->interlaced = 0;
> +
> + for (i = 0; i < field->nb_planes; i++) {
> + outpicref->data[i] = inpicref->data[i] +
> + (field->type == FIELD_TYPE_BOTTOM ? inpicref->linesize[i] : 0);
> + outpicref->linesize[i] = 2 * inpicref->linesize[i];
> + }
> +
> + if (desc->flags & PIX_FMT_PAL || desc->flags & PIX_FMT_PSEUDOPAL)
> + outpicref->data[1] = inpicref->data[1];
> +
> + return ff_start_frame(inlink->dst->outputs[0], outpicref);
> +}
> +
> +static int draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
> +{
> + return ff_draw_slice(inlink->dst->outputs[0], y/2, h/2, slice_dir);
> +}
> +
> +static const AVFilterPad field_inputs[] = {
> + {
> + .name = "default",
> + .type = AVMEDIA_TYPE_VIDEO,
> + .get_video_buffer = ff_null_get_video_buffer,
> + .start_frame = start_frame,
> + .draw_slice = draw_slice,
> + .end_frame = ff_null_end_frame,
> + },
> + { NULL }
> +};
> +
> +static const AVFilterPad field_outputs[] = {
> + {
> + .name = "default",
> + .type = AVMEDIA_TYPE_VIDEO,
> + .config_props = config_props_output,
> + },
> + { NULL }
> +};
> +
> +AVFilter avfilter_vf_field = {
> + .name = "field",
> + .description = NULL_IF_CONFIG_SMALL("Extract a field from the input image."),
> +
> + .priv_size = sizeof(FieldContext),
> + .init = init,
> +
> + .inputs = field_inputs,
> + .outputs = field_outputs,
> + .priv_class = &field_class,
nit: weird align
> +};
> diff --git a/tests/fate/avfilter.mak b/tests/fate/avfilter.mak
> index b931244..239fe64 100644
> --- a/tests/fate/avfilter.mak
> +++ b/tests/fate/avfilter.mak
> @@ -11,6 +11,7 @@ FATE_LAVFI = fate-lavfi-alphaextract_rgb \
> fate-lavfi-drawbox \
> fate-lavfi-edgedetect \
> fate-lavfi-fade \
> + fate-lavfi-field \
> fate-lavfi-idet \
> fate-lavfi-life \
> fate-lavfi-null \
> diff --git a/tests/lavfi-regression.sh b/tests/lavfi-regression.sh
> index 703d56c..76b2e5a 100755
> --- a/tests/lavfi-regression.sh
> +++ b/tests/lavfi-regression.sh
> @@ -111,6 +111,7 @@ do_lavfi_pixfmts(){
> do_lavfi_pixfmts "copy" ""
> do_lavfi_pixfmts "crop" "100:100:100:100"
> do_lavfi_pixfmts "hflip" ""
> +do_lavfi_pixfmts "field" "field" "bottom"
why the double "field"?
[...]
Not much to say, that port looks pretty OK, feel free to dismiss any
comment I have, and push with the mp drop when you think it's fine (unless
someone doesn't agree).
--
Clément B.
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