[FFmpeg-devel] [PATCH v5 2/3] vf_find_rect.c: use the optimized sad function to improve the find performance

[Michael Niedermayer]

Hi

On Wed, Jun 12, 2019 at 06:57:30PM +0800, lance.lmwang at gmail.com wrote:
> From: Limin Wang <lance.lmwang at gmail.com>
> 
> benchmark on x86_64: 6.4 -> 16 with below command:
> ./ffmpeg  -i 1920x1080.mp4 -vf find_rect=./find.tif,cover_rect=./cover.jpg:mode=cover -f null -
> 6.4 fps -> 16fps
> 
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  libavfilter/vf_find_rect.c | 53 +++++++++++++++-----------------------
>  1 file changed, 21 insertions(+), 32 deletions(-)
> 
> diff --git a/libavfilter/vf_find_rect.c b/libavfilter/vf_find_rect.c
> index ee6c3f4b45..ed15885bc2 100644
> --- a/libavfilter/vf_find_rect.c
> +++ b/libavfilter/vf_find_rect.c
> @@ -26,6 +26,7 @@
>  #include "libavutil/imgutils.h"
>  #include "libavutil/opt.h"
>  #include "internal.h"
> +#include "scene_sad.h"
>  
>  #include "lavfutils.h"
>  #include "lswsutils.h"
> @@ -36,6 +37,8 @@ typedef struct FOCContext {
>      AVClass *class;
>      float threshold;
>      int mipmaps;
> +    ff_scene_sad_fn sad;
> +    int bitdepth;
>      int xmin, ymin, xmax, ymax;
>      char *obj_filename;
>      int last_x, last_y;
> @@ -103,54 +106,40 @@ static AVFrame *downscale(AVFrame *in)
>      return frame;
>  }
>  
> -static float compare(const AVFrame *haystack, const AVFrame *obj, int offx, int offy)
> +static float compare_sad(FOCContext *foc, AVFrame *haystack, AVFrame *obj, int offx, int offy)
>  {
> -    int x,y;
> -    int o_sum_v = 0;
> -    int h_sum_v = 0;
> -    int64_t oo_sum_v = 0;
> -    int64_t hh_sum_v = 0;
> -    int64_t oh_sum_v = 0;
> -    float c;
> +    uint64_t sad = 0;
>      int n = obj->height * obj->width;
> -    const uint8_t *odat = obj     ->data[0];
> +    double mafd;
> +    const uint8_t *odat = obj->data[0];
>      const uint8_t *hdat = haystack->data[0] + offx + offy * haystack->linesize[0];
> -    int64_t o_sigma, h_sigma;
> -
> -    for(y = 0; y < obj->height; y++) {
> -        for(x = 0; x < obj->width; x++) {
> -            int o_v = odat[x];
> -            int h_v = hdat[x];
> -            o_sum_v += o_v;
> -            h_sum_v += h_v;
> -            oo_sum_v += o_v * o_v;
> -            hh_sum_v += h_v * h_v;
> -            oh_sum_v += o_v * h_v;
> -        }
> -        odat += obj->linesize[0];
> -        hdat += haystack->linesize[0];
> -    }
> -    o_sigma = n*oo_sum_v - o_sum_v*(int64_t)o_sum_v;
> -    h_sigma = n*hh_sum_v - h_sum_v*(int64_t)h_sum_v;
>  
> -    if (o_sigma == 0 || h_sigma == 0)
> -        return 1.0;
> +    foc->sad(hdat, haystack->linesize[0], odat, obj->linesize[0],
> +            obj->width, obj->height, &sad);
> +    emms_c();
> +    mafd = (double)sad / n / (1ULL << foc->bitdepth);

mixing floating point and MMX in the same function is likely not
safe

also SAD wont recognize objects that are a different contrast or brightness

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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