[FFmpeg-devel] [PATCH] Add crop filter

[Michael Niedermayer]

On Tue, Oct 06, 2009 at 12:58:41AM +0200, Stefano Sabatini wrote:
> Hi,
> 
> let's start to add some filter to the main repo.
> 
> As long as I'll add them, I plan to remove them from the soc repo, so
> that further changes will be directly applied to the main repo.
> 
> In the meaningwhile though regression tests will be yet performed in
> soc.
> 
> In attachment there is the exact copy of the crop filter you can find
> in the soc repo.
> 
> Regards.
> -- 
> FFmpeg = Fundamental & Friendly Merciless Portable Epic Geisha

>  Makefile     |    2 
>  allfilters.c |    3 -
>  vf_crop.c    |  160 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 162 insertions(+), 3 deletions(-)
> 32cd7ccf67a2827a81eb82007922aee682411066  add-crop-filter.patch
> Index: ffmpeg/libavfilter/Makefile
> ===================================================================
> --- ffmpeg.orig/libavfilter/Makefile	2009-10-06 00:37:21.000000000 +0200
> +++ ffmpeg/libavfilter/Makefile	2009-10-06 00:37:45.000000000 +0200
> @@ -11,6 +11,6 @@
>         defaults.o                                                       \
>         formats.o                                                        \
>  
> -#OBJS-$(CONFIG_XXX_FILTER)    += vf_xxx.o
> +OBJS-$(CONFIG_CROP_FILTER)    += vf_crop.o
>  
>  include $(SUBDIR)../subdir.mak
> Index: ffmpeg/libavfilter/allfilters.c
> ===================================================================
> --- ffmpeg.orig/libavfilter/allfilters.c	2009-10-06 00:37:55.000000000 +0200
> +++ ffmpeg/libavfilter/allfilters.c	2009-10-06 00:38:06.000000000 +0200
> @@ -34,6 +34,5 @@
>          return;
>      initialized = 1;
>  
> -//    REGISTER_FILTER (CROP,crop,vf);
> -
> +    REGISTER_FILTER (CROP,crop,vf);
>  }
> Index: ffmpeg/libavfilter/vf_crop.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ ffmpeg/libavfilter/vf_crop.c	2009-10-06 00:37:11.000000000 +0200
> @@ -0,0 +1,160 @@
> +/*
> + * video crop filter
> + * copyright (c) 2007 Bobby Bingham
> + *
> + * 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 <stdio.h>
> +
> +#include "avfilter.h"
> +
> +typedef struct
> +{

> +    int  x,  y,  w,  h;
> +    int cx, cy, cw, ch;

these are missing doxygen comments explaining what they are


> +
> +    int bpp;                //< bytes per pixel
> +    int hsub, vsub;         //< chroma subsampling
> +} CropContext;
> +

> +static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
> +{
> +    CropContext *crop = ctx->priv;
> +
> +    /* default parameters */
> +    crop->x = 0;
> +    crop->y = 0;

i would assume that the context is zeroed when its allocated, is that not so?


> +    crop->w = -1;
> +    crop->h = -1;
> +
> +    if(args)
> +        sscanf(args, "%d:%d:%d:%d", &crop->x, &crop->y, &crop->w, &crop->h);
> +
> +    return 0;
> +}
> +

> +static int config_input(AVFilterLink *link)
> +{
> +    CropContext *crop = link->dst->priv;
> +
> +    crop->cx = FFMIN(crop->x, link->w - 1);
> +    crop->cy = FFMIN(crop->y, link->h - 1);
> +    crop->cw = FFMIN(crop->w, link->w - crop->cx);
> +    crop->ch = FFMIN(crop->h, link->h - crop->cy);
> +
> +    if(crop->cw <= 0) crop->cw = link->w - crop->cx;
> +    if(crop->ch <= 0) crop->ch = link->h - crop->cy;

this seems to check for w/h < 0 while x/y are not checked ...


> +
> +    switch(link->format) {
> +    case PIX_FMT_RGB32:
> +    case PIX_FMT_BGR32:
> +        crop->bpp = 4;
> +        break;
> +    case PIX_FMT_RGB24:
> +    case PIX_FMT_BGR24:
> +        crop->bpp = 3;
> +        break;
> +    case PIX_FMT_RGB565:
> +    case PIX_FMT_RGB555:
> +    case PIX_FMT_BGR565:
> +    case PIX_FMT_BGR555:
> +    case PIX_FMT_GRAY16BE:
> +    case PIX_FMT_GRAY16LE:
> +        crop->bpp = 2;
> +        break;
> +    default:
> +        crop->bpp = 1;
> +    }
> +

> +    avcodec_get_chroma_sub_sample(link->format, &crop->hsub, &crop->vsub);
> +    crop->cx &= ~((1 << crop->hsub) - 1);
> +    crop->cw &= ~((1 << crop->hsub) - 1);
> +    crop->ch &= ~((1 << crop->vsub) - 1);

and cy?


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

In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
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