On 7/15/17, Peter Grosse <pe...@friiks.de> wrote:
> Use alpha value from alpha channel instead of selected component channel.
>
> Signed-off-by: Peter Grosse <pe...@friiks.de>
> ---
> libavfilter/vf_overlay.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/libavfilter/vf_overlay.c b/libavfilter/vf_overlay.c
> index 5c9f590957..cde09f5fb3 100644
> --- a/libavfilter/vf_overlay.c
> +++ b/libavfilter/vf_overlay.c
> @@ -508,7 +508,7 @@ static av_always_inline void blend_plane(AVFilterContext
> *ctx,
> int dst_hp = AV_CEIL_RSHIFT(dst_h, vsub);
> int yp = y>>vsub;
> int xp = x>>hsub;
> - uint8_t *s, *sp, *d, *dp, *a, *ap;
> + uint8_t *s, *sp, *d, *dp, *a, *ap, *da, *dap;
> int jmax, j, k, kmax;
>
> j = FFMAX(-yp, 0);
> @@ -517,12 +517,16 @@ static av_always_inline void
> blend_plane(AVFilterContext *ctx,
> + (yp+j) * dst->linesize[dst_plane]
> + dst_offset;
> ap = src->data[3] + (j<<vsub) * src->linesize[3];
> + if (main_has_alpha)
> + dap = dst->data[3] + (j<<vsub) * dst->linesize[3];
>
> for (jmax = FFMIN(-yp + dst_hp, src_hp); j < jmax; j++) {
> k = FFMAX(-xp, 0);
> d = dp + (xp+k) * dst_step;
> s = sp + k;
> a = ap + (k<<hsub);
> + if (main_has_alpha)
> + da = dap + (k<<hsub);
>
> for (kmax = FFMIN(-xp + dst_wp, src_wp); k < kmax; k++) {
> int alpha_v, alpha_h, alpha;
> @@ -545,16 +549,16 @@ static av_always_inline void
> blend_plane(AVFilterContext *ctx,
> // average alpha for color components, improve quality
> uint8_t alpha_d;
> if (hsub && vsub && j+1 < src_hp && k+1 < src_wp) {
> - alpha_d = (d[0] + d[src->linesize[3]] +
> - d[1] + d[src->linesize[3]+1]) >> 2;
> + alpha_d = (da[0] + da[src->linesize[3]] +
> + da[1] + da[src->linesize[3]+1]) >> 2;
> } else if (hsub || vsub) {
> alpha_h = hsub && k+1 < src_wp ?
> - (d[0] + d[1]) >> 1 : d[0];
> + (da[0] + da[1]) >> 1 : da[0];
> alpha_v = vsub && j+1 < src_hp ?
> - (d[0] + d[src->linesize[3]]) >> 1 : d[0];
> + (da[0] + da[src->linesize[3]]) >> 1 : da[0];
> alpha_d = (alpha_v + alpha_h) >> 1;
> } else
> - alpha_d = d[0];
> + alpha_d = da[0];
> alpha = UNPREMULTIPLY_ALPHA(alpha, alpha_d);
> }
> *d = FAST_DIV255(*d * (255 - alpha) + *s * alpha);
> --
> 2.13.0
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
how can one reproduce this bug?
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