[FFmpeg-devel] [PATCH] lavfi: add inverse telecine filter

[Michael Niedermayer]

On Fri, Mar 27, 2015 at 11:07:18AM +0530, Himangi Saraogi wrote:
> ---
>  Changelog                   |   1 +
>  doc/filters.texi            |  27 ++++
>  libavfilter/Makefile        |   1 +
>  libavfilter/allfilters.c    |   1 +
>  libavfilter/vf_detelecine.c | 345 ++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 375 insertions(+)
>  create mode 100644 libavfilter/vf_detelecine.c
> 
> diff --git a/Changelog b/Changelog
> index b0d0414..81c6eab 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -9,6 +9,7 @@ version <next>:
>  - libdcadec wrapper
>  - Drop support for nvenc API before 5.0
>  - nvenc H265 encoder
> +- Detelecine filter
>  
>  
>  version 2.6:
> diff --git a/doc/filters.texi b/doc/filters.texi
> index f2999f2..15f8ed5 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -3728,6 +3728,33 @@ FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
>  
>  @end table
>  
> + at section detelecine
> +
> +Apply an exact inverse of the telecine operation. It requires a predefined
> +pattern specified using the pattern option which must be the same as that passed
> +to the telecine filter.
> +
> +This filter accepts the following options:
> +
> + at table @option
> + at item first_field
> + at table @samp
> + at item top, t
> +top field first
> + at item bottom, b
> +bottom field first
> +The default value is @code{top}.
> + at end table
> +
> + at item pattern
> +A string of numbers representing the pulldown pattern you wish to apply.
> +The default value is @code{23}.
> +
> + at item start_frame
> +A number representing position of the first frame with respect to the telecine
> +pattern. This is to be used if the stream is cut. The default value is @code{0}.
> + at end table
> +
>  @section drawbox
>  
>  Draw a colored box on the input image.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 2cde029..73e7adf 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -112,6 +112,7 @@ OBJS-$(CONFIG_DECIMATE_FILTER)               += vf_decimate.o
>  OBJS-$(CONFIG_DEJUDDER_FILTER)               += vf_dejudder.o
>  OBJS-$(CONFIG_DELOGO_FILTER)                 += vf_delogo.o
>  OBJS-$(CONFIG_DESHAKE_FILTER)                += vf_deshake.o
> +OBJS-$(CONFIG_DETELECINE_FILTER)             += vf_detelecine.o
>  OBJS-$(CONFIG_DRAWBOX_FILTER)                += vf_drawbox.o
>  OBJS-$(CONFIG_DRAWGRID_FILTER)               += vf_drawbox.o
>  OBJS-$(CONFIG_DRAWTEXT_FILTER)               += vf_drawtext.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 0288082..6bc01c5 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -128,6 +128,7 @@ void avfilter_register_all(void)
>      REGISTER_FILTER(DEJUDDER,       dejudder,       vf);
>      REGISTER_FILTER(DELOGO,         delogo,         vf);
>      REGISTER_FILTER(DESHAKE,        deshake,        vf);
> +    REGISTER_FILTER(DETELECINE,     detelecine,     vf);
>      REGISTER_FILTER(DRAWBOX,        drawbox,        vf);
>      REGISTER_FILTER(DRAWGRID,       drawgrid,       vf);
>      REGISTER_FILTER(DRAWTEXT,       drawtext,       vf);
> diff --git a/libavfilter/vf_detelecine.c b/libavfilter/vf_detelecine.c
> new file mode 100644
> index 0000000..27463fe
> --- /dev/null
> +++ b/libavfilter/vf_detelecine.c
> @@ -0,0 +1,345 @@
> +/*
> + * Copyright (c) 2015 Himangi Saraogi <himangi774 at gmail.com>
> + *
> + * 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 detelecine filter.
> + */
> +
> +
> +#include "libavutil/avstring.h"
> +#include "libavutil/imgutils.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/pixdesc.h"
> +#include "avfilter.h"
> +#include "formats.h"
> +#include "internal.h"
> +#include "video.h"
> +
> +typedef struct {
> +    const AVClass *class;
> +    int first_field;
> +    char *pattern;
> +    int start_frame;
> +    unsigned int pattern_pos;
> +    unsigned int nskip_fields;
> +    int64_t start_time;
> +
> +    AVRational pts;

> +    double ts_unit;

this should be a AVRational or some int64_t / int64_t in case there is
insufficient precission in AVRational.
floating point should be avoided so that the same values are
produced on every platform, which is important for regression testig



[...]
> +        frame->pts = ((s->start_time == AV_NOPTS_VALUE) ? 0 : s->start_time) +
> +                     outlink->frame_count * s->ts_unit;

this could use av_rescale()

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct answer.
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