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

[Lance Wang]

On Sat, Jun 15, 2019 at 3:16 AM Michael Niedermayer <michael at niedermayer.cc>
wrote:

> 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
>
> The goal is make the common user to use it more friendly.  When I'm do the
testing,  I have got some object
file isn't gray image,  I had to use ffmpeg convert it to gray every time.
although I don't care for only gray color is used
clearly.

How about to add description to explain we use gray color only for the
compare now.


> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Those who are best at talking, realize last or never when they are wrong.
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