[FFmpeg-devel] avfilter: add tpad filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 doc/filters.texi         |  22 ++++++
 libavfilter/Makefile     |   1 +
 libavfilter/allfilters.c |   1 +
 libavfilter/vf_tpad.c    | 166 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 190 insertions(+)
 create mode 100644 libavfilter/vf_tpad.c

On Tue, Oct 30, 2018 at 3:27 PM Paul B Mahol <onemda@gmail.com> wrote:

> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  doc/filters.texi         |  22 ++++++
>  libavfilter/Makefile     |   1 +
>  libavfilter/allfilters.c |   1 +
>  libavfilter/vf_tpad.c    | 166 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 190 insertions(+)
>  create mode 100644 libavfilter/vf_tpad.c
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 9b84b1145b..6dda780aa0 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -16676,6 +16676,28 @@ embedded peak information in display metadata is
> not reliable or when tone
>  mapping from a lower range to a higher range.
>  @end table
>
> +@section tpad
> +
> +Temporarily pad video frames.
> +
> +The filter accepts the following options:
> +
> +@table @option
> +@item start
> +Specify number of delay frames before input video stream.
> +
> +@item stop
> +Specify number of padding frames after input video stream.
> +Set to -1 to pad indefinitely.
> +
> +@item color
> +Specify the color of the padded area. For the syntax of this option,
> +check the @ref{color syntax,,"Color" section in the ffmpeg-utils
> +manual,ffmpeg-utils}.
> +
> +The default value of @var{color} is "black".
> +@end table
> +
>  @anchor{transpose}
>  @section transpose
>
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index c35cd8f422..51e48efc2e 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -383,6 +383,7 @@ OBJS-$(CONFIG_TMIX_FILTER)                   +=
> vf_mix.o framesync.o
>  OBJS-$(CONFIG_TONEMAP_FILTER)                += vf_tonemap.o colorspace.o
>  OBJS-$(CONFIG_TONEMAP_OPENCL_FILTER)         += vf_tonemap_opencl.o
> colorspace.o opencl.o \
>                                                  opencl/tonemap.o
> opencl/colorspace_common.o
> +OBJS-$(CONFIG_TPAD_FILTER)                   += vf_tpad.o
>  OBJS-$(CONFIG_TRANSPOSE_FILTER)              += vf_transpose.o
>  OBJS-$(CONFIG_TRANSPOSE_NPP_FILTER)          += vf_transpose_npp.o
>  OBJS-$(CONFIG_TRIM_FILTER)                   += trim.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index d5a211bda5..6052cb8c3c 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -365,6 +365,7 @@ extern AVFilter ff_vf_tlut2;
>  extern AVFilter ff_vf_tmix;
>  extern AVFilter ff_vf_tonemap;
>  extern AVFilter ff_vf_tonemap_opencl;
> +extern AVFilter ff_vf_tpad;
>  extern AVFilter ff_vf_transpose;
>  extern AVFilter ff_vf_transpose_npp;
>  extern AVFilter ff_vf_trim;
> diff --git a/libavfilter/vf_tpad.c b/libavfilter/vf_tpad.c
> new file mode 100644
> index 0000000000..e59037ca56
> --- /dev/null
> +++ b/libavfilter/vf_tpad.c
> @@ -0,0 +1,166 @@
> +/*
> + * Copyright (c) 2018 Paul B Mahol
> + *
> + * 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
> + */
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/channel_layout.h"
> +#include "libavutil/opt.h"
> +#include "avfilter.h"
> +#include "audio.h"
> +#include "filters.h"
> +#include "internal.h"
> +#include "formats.h"
> +#include "drawutils.h"
> +
> +typedef struct TPadContext {
> +    const AVClass *class;
> +    int pad_start;
> +    int pad_stop;
> +    uint8_t rgba_color[4];  ///< color for the padding area
> +
> +    FFDrawContext draw;
> +    FFDrawColor color;
> +    int64_t pts;
> +    int eof;
> +} TPadContext;
> +
> +#define OFFSET(x) offsetof(TPadContext, x)
> +#define VF AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
> +
> +static const AVOption tpad_options[] = {
> +    { "start", "set the number of frames to delay input",
> OFFSET(pad_start),  AV_OPT_TYPE_INT,   {.i64=0},        0, INT_MAX, VF },
> +    { "stop",  "set the number of frames to add after input finished",
> OFFSET(pad_stop),   AV_OPT_TYPE_INT,   {.i64=0},       -1, INT_MAX, VF },
> +    { "color", "set the color of the added frames",
> OFFSET(rgba_color), AV_OPT_TYPE_COLOR, {.str="black"},  0,       0, VF },
> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(tpad);
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    return ff_set_common_formats(ctx, ff_draw_supported_pixel_formats(0));
> +}
> +
> +static int activate(AVFilterContext *ctx)
> +{
> +    AVFilterLink *inlink = ctx->inputs[0];
> +    AVFilterLink *outlink = ctx->outputs[0];
> +    TPadContext *s = ctx->priv;
> +    AVFrame *frame = NULL;
> +    int ret, status;
> +    int64_t pts;
> +
> +    FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
> +
> +    if (s->pad_start > 0 && ff_outlink_frame_wanted(outlink)) {
> +        frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
> +        if (!frame)
> +            return AVERROR(ENOMEM);
> +        ff_fill_rectangle(&s->draw, &s->color,
> +                          frame->data, frame->linesize,
> +                          0, 0, frame->width, frame->height);
> +        frame->pts = s->pts;
> +        s->pts += av_rescale_q(1, av_inv_q(outlink->frame_rate),
> outlink->time_base);
> +        s->pad_start--;
> +        return ff_filter_frame(outlink, frame);
> +    }
> +
> +    if (!s->eof && !s->pad_start) {
> +        ret = ff_inlink_consume_frame(inlink, &frame);
> +        if (ret < 0)
> +            return ret;
> +        if (ret > 0) {
> +            frame->pts += s->pts;
> +            return ff_filter_frame(outlink, frame);
> +        }
> +    }
> +
> +    if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
> +        if (status == AVERROR_EOF) {
> +            if (!s->pad_stop) {
> +                ff_outlink_set_status(outlink, status, pts);
> +                return 0;
> +            }
> +            s->eof = 1;
> +            s->pts += pts;
> +        }
> +    }
> +
> +    if (s->eof) {
> +        if (!s->pad_stop) {
> +            ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
> +            return 0;
> +        }
> +        frame = ff_get_video_buffer(outlink, outlink->w, outlink->h);
> +        if (!frame)
> +            return AVERROR(ENOMEM);
> +        ff_fill_rectangle(&s->draw, &s->color,
> +                          frame->data, frame->linesize,
> +                          0, 0, frame->width, frame->height);
> +        frame->pts = s->pts;
> +        s->pts += av_rescale_q(1, av_inv_q(outlink->frame_rate),
> outlink->time_base);
> +        if (s->pad_stop > 0)
> +            s->pad_stop--;
> +        return ff_filter_frame(outlink, frame);
> +    }
> +
> +    if (!s->pad_start)
> +        FF_FILTER_FORWARD_WANTED(outlink, inlink);
> +
> +    return FFERROR_NOT_READY;
> +}
> +
> +static int config_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    TPadContext *s = ctx->priv;
> +
> +    ff_draw_init(&s->draw, inlink->format, 0);
> +    ff_draw_color(&s->draw, &s->color, s->rgba_color);
> +
> +    return 0;
> +}
> +
> +static const AVFilterPad tpad_inputs[] = {
> +    {
> +        .name         = "default",
> +        .type         = AVMEDIA_TYPE_VIDEO,
> +        .config_props = config_input,
> +    },
> +    { NULL }
> +};
> +
> +static const AVFilterPad tpad_outputs[] = {
> +    {
> +        .name = "default",
> +        .type = AVMEDIA_TYPE_VIDEO,
> +    },
> +    { NULL }
> +};
> +
> +AVFilter ff_vf_tpad = {
> +    .name          = "tpad",
> +    .description   = NULL_IF_CONFIG_SMALL("Temporarily pad video
> frames."),
> +    .priv_size     = sizeof(TPadContext),
> +    .priv_class    = &tpad_class,
> +    .query_formats = query_formats,
> +    .inputs        = tpad_inputs,
> +    .outputs       = tpad_outputs,
> +    .activate      = activate,
> +};
>

Nice. Thanks.

A couple of suggestions:

1) allow the user to supply duration as well.

2) allow cloning the nearest frame. First frame for start delay and last
frame for end padding.

Gyan