[FFmpeg-devel] [PATCH v5 1/3] libavfilter/vf_find_rect: convert the object image to gray8 format instead of failed directly

[Michael Niedermayer]

On Wed, Jun 12, 2019 at 06:57:29PM +0800, lance.lmwang at gmail.com wrote:
> From: Limin Wang <lance.lmwang at gmail.com>
> 
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  doc/filters.texi           |  2 +-
>  libavfilter/vf_find_rect.c | 39 +++++++++++++++++++++++++++-----------
>  2 files changed, 29 insertions(+), 12 deletions(-)
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index ec1c7c7591..90c57430a6 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -10150,7 +10150,7 @@ It accepts the following options:
>  
>  @table @option
>  @item object
> -Filepath of the object image, needs to be in gray8.
> +Filepath of the object image.
>  
>  @item threshold
>  Detection threshold, default is 0.5.
> diff --git a/libavfilter/vf_find_rect.c b/libavfilter/vf_find_rect.c
> index d7e6579af7..ee6c3f4b45 100644
> --- a/libavfilter/vf_find_rect.c
> +++ b/libavfilter/vf_find_rect.c
> @@ -28,6 +28,7 @@
>  #include "internal.h"
>  
>  #include "lavfutils.h"
> +#include "lswsutils.h"
>  
>  #define MAX_MIPMAPS 5
>  
> @@ -244,6 +245,9 @@ static av_cold int init(AVFilterContext *ctx)
>  {
>      FOCContext *foc = ctx->priv;
>      int ret, i;
> +    uint8_t *tmp_data[4] = { NULL };
> +    int tmp_linesize[4], width, height;
> +    enum AVPixelFormat pix_fmt;
>  
>      if (!foc->obj_filename) {
>          av_log(ctx, AV_LOG_ERROR, "object filename not set\n");
> @@ -254,24 +258,37 @@ static av_cold int init(AVFilterContext *ctx)
>      if (!foc->obj_frame)
>          return AVERROR(ENOMEM);
>  
> -    if ((ret = ff_load_image(foc->obj_frame->data, foc->obj_frame->linesize,
> -                             &foc->obj_frame->width, &foc->obj_frame->height,
> -                             &foc->obj_frame->format, foc->obj_filename, ctx)) < 0)
> -        return ret;
> -
> -    if (foc->obj_frame->format != AV_PIX_FMT_GRAY8) {
> -        av_log(ctx, AV_LOG_ERROR, "object image is not a grayscale image\n");
> -        return AVERROR(EINVAL);
> -    }
> +    if ((ret = ff_load_image(tmp_data, tmp_linesize,
> +                             &width, &height,
> +                             &pix_fmt, foc->obj_filename, ctx)) < 0)
> +        goto error;
> +
> +    /* convert object image to gray8 format with same width and height */
> +    foc->obj_frame->format = AV_PIX_FMT_GRAY8;
> +    foc->obj_frame->width  = width;
> +    foc->obj_frame->height = height;
> +    if ((ret = ff_scale_image(foc->obj_frame->data, foc->obj_frame->linesize,
> +                    foc->obj_frame->width, foc->obj_frame->height, foc->obj_frame->format,
> +                    tmp_data, tmp_linesize, width, height, pix_fmt, ctx)) < 0)
> +        goto error;
> +    av_freep(&tmp_data[0]);

Iam not sure i understand what this patch is intending to do

Before a grayscale image was needed, after the patch anything is accepted but
only grayscale is used. This is quite unexpected for a user who might expect
color to be used if color is accpeted.
Generally, doing something that is unexpected by the user is not good

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

Those who are best at talking, realize last or never when they are wrong.
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