From: Clément Bœsch <[email protected]> Current code divides before increasing precision.
Also reduce upper bound for strength from 255 to 64. This will prevent an overflow in the SSSE3 and MMX filter_line code: delta is expressed as an u16 being shifted by 2 to the left. If it overflows, having a strength not above 64 will make sure that m is set to 0 (making the m*m*delta >> 14 expression void). A value above 64 should not make any sense unless gradfun is used as a blur filter. Signed-off-by: Anton Khirnov <[email protected]> --- doc/filters.texi | 2 +- libavfilter/vf_gradfun.c | 2 +- libavfilter/x86/vf_gradfun.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/doc/filters.texi b/doc/filters.texi index 9b39ea5..88888c6 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -1142,7 +1142,7 @@ The filter takes two optional parameters, separated by ':': @var{strength} is the maximum amount by which the filter will change any one pixel. Also the threshold for detecting nearly flat -regions. Acceptable values range from .51 to 255, default value is +regions. Acceptable values range from .51 to 64, default value is 1.2, out-of-range values will be clipped to the valid range. @var{radius} is the neighborhood to fit the gradient to. A larger diff --git a/libavfilter/vf_gradfun.c b/libavfilter/vf_gradfun.c index 80b7e41..900ef60 100644 --- a/libavfilter/vf_gradfun.c +++ b/libavfilter/vf_gradfun.c @@ -128,7 +128,7 @@ static av_cold int init(AVFilterContext *ctx, const char *args) if (args) sscanf(args, "%f:%d", &thresh, &radius); - thresh = av_clipf(thresh, 0.51, 255); + thresh = av_clipf(thresh, 0.51, 64); gf->thresh = (1 << 15) / thresh; gf->radius = av_clip((radius + 1) & ~1, 4, 32); diff --git a/libavfilter/x86/vf_gradfun.c b/libavfilter/x86/vf_gradfun.c index b4ca86c..75c117a 100644 --- a/libavfilter/x86/vf_gradfun.c +++ b/libavfilter/x86/vf_gradfun.c @@ -62,8 +62,8 @@ static void gradfun_filter_line_mmxext(uint8_t *dst, uint8_t *src, uint16_t *dc, "pminsw %%mm7, %%mm2 \n" // m = -max(0, 127-m) "pmullw %%mm2, %%mm2 \n" "paddw %%mm4, %%mm0 \n" // pix += dither - "pmulhw %%mm2, %%mm1 \n" "psllw $2, %%mm1 \n" // m = m*m*delta >> 14 + "pmulhw %%mm2, %%mm1 \n" "paddw %%mm1, %%mm0 \n" // pix += m "psraw $7, %%mm0 \n" "packuswb %%mm0, %%mm0 \n" -- 1.7.10.4 _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
