[FFmpeg-devel] [PATCH] lavfi: port perspective filter from libmpcodecs

Paul B Mahol onemda at gmail.com
Sun Jul 14 18:07:35 CEST 2013


On 7/14/13, Stefano Sabatini <stefasab at gmail.com> wrote:

You reviewed older version.

> On date Friday 2013-07-12 21:03:07 +0000, Paul B Mahol encoded:
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>>  doc/filters.texi             |  22 +++
>>  libavfilter/Makefile         |   1 +
>>  libavfilter/allfilters.c     |   1 +
>>  libavfilter/vf_perspective.c | 382
>> +++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 406 insertions(+)
>>  create mode 100644 libavfilter/vf_perspective.c
>>
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index bcc9687..9720ac2 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -5717,6 +5717,28 @@ pad="2*iw:2*ih:ow-iw:oh-ih"
>>  @end example
>>  @end itemize
>>
>> + at section perspective
>> +
>> +Correct perspective of videos not recorded perpendicular to the screen.
>> +
>> +A description of the accepted parameters follows.
>> +
>> + at table @option
>> + at item x0, y0, x1, y1, x2, y2, x3, y3,
>
> Separate line for each item
> @item x0
> @item y0
> ...

Done.

>
>> +Set coordinates of top left, top right, bottom left and bottom right
>> corners.
>> +
>> + at item interpolation
>> +Set interpolation for perspective correction.
>> +
>> +It accepts the following values:
>
>> + at table @option
>
> @table @samp

Done.

>
>> + at item linear
>> + at item cubic
>> + at end table
>> +
>> +Default one is @var{linear}.
>
> @samp{linear}

Done,

>
>> + at end table
>> +
>>  @section pixdesctest
>>
>>  Pixel format descriptor test filter, mainly useful for internal
>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>> index 306b24c..7f10409 100644
>> --- a/libavfilter/Makefile
>> +++ b/libavfilter/Makefile
>> @@ -166,6 +166,7 @@ OBJS-$(CONFIG_OVERLAY_FILTER)                +=
>> vf_overlay.o dualinput.o
>>  OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o
>>  OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
>>  OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
>> +OBJS-$(CONFIG_PERSPECTIVE_FILTER)            += vf_perspective.o
>>  OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o
>>  OBJS-$(CONFIG_PP_FILTER)                     += vf_pp.o
>>  OBJS-$(CONFIG_PSNR_FILTER)                   += vf_psnr.o dualinput.o
>> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>> index 26472f8..bda6e3c 100644
>> --- a/libavfilter/allfilters.c
>> +++ b/libavfilter/allfilters.c
>> @@ -161,6 +161,7 @@ void avfilter_register_all(void)
>>      REGISTER_FILTER(OWDENOISE,      owdenoise,      vf);
>>      REGISTER_FILTER(PAD,            pad,            vf);
>>      REGISTER_FILTER(PERMS,          perms,          vf);
>> +    REGISTER_FILTER(PERSPECTIVE,    perspective,    vf);
>>      REGISTER_FILTER(PIXDESCTEST,    pixdesctest,    vf);
>>      REGISTER_FILTER(PP,             pp,             vf);
>>      REGISTER_FILTER(PSNR,           psnr,           vf);
>> diff --git a/libavfilter/vf_perspective.c b/libavfilter/vf_perspective.c
>> new file mode 100644
>> index 0000000..09eb548
>> --- /dev/null
>> +++ b/libavfilter/vf_perspective.c
>> @@ -0,0 +1,382 @@
>> +/*
>> + * Copyright (c) 2002 Michael Niedermayer <michaelni at gmx.at>
>> + *
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2 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 General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU 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 <float.h>
>> +
>> +#include "libavutil/pixdesc.h"
>> +#include "libavutil/opt.h"
>> +#include "avfilter.h"
>> +#include "formats.h"
>> +#include "internal.h"
>> +#include "video.h"
>> +
>> +#define SUB_PIXEL_BITS  8
>> +#define SUB_PIXELS      (1 << SUB_PIXEL_BITS)
>> +#define COEFF_BITS      11
>> +
>> +#define LINEAR 0
>> +#define CUBIC  1
>> +
>> +typedef struct PerspectiveContext {
>> +    const AVClass *class;
>> +    double ref[4][2];
>> +    int32_t (*pv)[2];
>> +    int32_t coeff[SUB_PIXELS][4];
>> +    int interpolation;
>> +    int linesize;
>> +    int hsub, vsub;
>> +    int nb_planes;
>> +
>> +    void (*perspective)(struct PerspectiveContext *s,
>> +                        uint8_t *dst, int dst_linesize,
>> +                        uint8_t *src, int src_linesize,
>> +                        int w, int h, int hsub, int vsub);
>> +} PerspectiveContext;
>> +
>> +#define OFFSET(x) offsetof(PerspectiveContext, x)
>> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
>> +
>> +static const AVOption perspective_options[] = {
>> +    { "x0", "", OFFSET(ref[0][0]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "y0", "", OFFSET(ref[0][1]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "x1", "", OFFSET(ref[1][0]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "y1", "", OFFSET(ref[1][1]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "x2", "", OFFSET(ref[2][0]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "y2", "", OFFSET(ref[2][1]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "x3", "", OFFSET(ref[3][0]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>> +    { "y3", "", OFFSET(ref[3][1]), AV_OPT_TYPE_DOUBLE, {.dbl=0},
>> -DBL_MAX, DBL_MAX, FLAGS },
>
> add help here, so it is shown in the automatic output
> x0 -> set top left x position
> y0 -> set top left y position
> ...

Already done.

>
>> +    { "interpolation", "", OFFSET(interpolation), AV_OPT_TYPE_INT,
>> {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },
>
> same here

Done.

>
>> +    {      "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0,
>> FLAGS, "interpolation" },
>> +    {       "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC},  0, 0,
>> FLAGS, "interpolation" },
>
>
>> +    { NULL }
>> +};
>> +
>> +AVFILTER_DEFINE_CLASS(perspective);
>> +
>> +static int query_formats(AVFilterContext *ctx)
>> +{
>> +    static const enum AVPixelFormat pix_fmts[] = {
>> +        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
>> +        AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
>> AV_PIX_FMT_YUVJ422P,AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,
>> +        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P,
>> AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
>> +        AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8,
>> AV_PIX_FMT_NONE
>> +    };
>> +
>> +    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
>> +    return 0;
>> +}
>> +
>
>> +static inline double get_coeff(double d)
>> +{
>> +    double coeff, A = -0.60;
>> +
>> +    d = fabs(d);
>> +
>> +    if (d < 1.0)
>> +        coeff = (1.0 - (A + 3.0) * d * d + (A + 2.0) * d * d * d);
>> +    else if (d < 2.0)
>> +        coeff = (-4.0 * A + 8.0 * A * d - 5.0 * A * d * d + A * d * d *
>> d);
>> +    else
>> +        coeff = 0.0;
>> +
>> +    return coeff;
>> +}
>
> If you understand the math please add some explanation here, so the
> code is not completely obfuscated, or try to get some explanations out
> of michaelni's head.

It can be added later.

>
> [...]
>
> Should be good otherwise, assuming the output is the same as that of
> mp=perspective (I can't get mp=perspective to work here).

Applied and mp one removed.


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