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swscale/alphablend: Support SWS_ALPHA_BLEND_CHECKERBOARD 

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2015-08-09 17:11:53 +02:00
parent 87100e828a
commit c5ebeaa308
4 changed files with 21 additions and 11 deletions
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3
doc/scaler.texi
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@ -130,6 +130,9 @@ Default value is @samp{none}.
@item uniform_color
Blend onto a uniform background color
@item checkerboard
Blend onto a checkerboard
@item none
No blending

27
libswscale/alphablend.c
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@ -32,10 +32,17 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
unsigned off = 1<<desc->comp[0].depth_minus1;
unsigned shift = desc->comp[0].depth_minus1 + 1;
unsigned max = (1<<shift) - 1;
int target_table[3];
int target_table[2][3];
for (plane = 0; plane < plane_count; plane++)
target_table[plane] = plane && !(desc->flags & AV_PIX_FMT_FLAG_RGB) ? 1<<desc->comp[0].depth_minus1 : 0;
for (plane = 0; plane < plane_count; plane++) {
int a = 0, b = 0;
if (c->alphablend == SWS_ALPHA_BLEND_CHECKERBOARD) {
a = (1<<desc->comp[0].depth_minus1)/2;
b = 3*(1<<desc->comp[0].depth_minus1)/2;
}
target_table[0][plane] = plane && !(desc->flags & AV_PIX_FMT_FLAG_RGB) ? 1<<desc->comp[0].depth_minus1 : a;
target_table[1][plane] = plane && !(desc->flags & AV_PIX_FMT_FLAG_RGB) ? 1<<desc->comp[0].depth_minus1 : b;
}
av_assert0(plane_count == nb_components - 1);
if (desc->flags & AV_PIX_FMT_FLAG_PLANAR) {
@ -47,16 +54,15 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
const uint16_t *s = src[plane ] + srcStride[plane] * y;
const uint16_t *a = src[plane_count] + srcStride[plane_count] * y;
uint16_t *d = dst[plane ] + dstStride[plane] * y;
unsigned target = target_table[plane];
if ((!isBE(c->srcFormat)) == !HAVE_BIGENDIAN) {
for (x = 0; x < w; x++) {
unsigned u = s[x]*a[x] + target*(max-a[x]) + off;
unsigned u = s[x]*a[x] + target_table[((x^y)>>5)&1][plane]*(max-a[x]) + off;
d[x] = av_clip((u + (u >> shift)) >> shift, 0, max);
}
} else {
for (x = 0; x < w; x++) {
unsigned aswap =av_bswap16(a[x]);
unsigned u = av_bswap16(s[x])*aswap + target*(max-aswap) + off;
unsigned u = av_bswap16(s[x])*aswap + target_table[((x^y)>>5)&1][plane]*(max-aswap) + off;
d[x] = av_clip((u + (u >> shift)) >> shift, 0, max);
}
}
@ -64,9 +70,8 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
const uint8_t *s = src[plane ] + srcStride[plane] * y;
const uint8_t *a = src[plane_count] + srcStride[plane_count] * y;
uint8_t *d = dst[plane ] + dstStride[plane] * y;
unsigned target = target_table[plane];
for (x = 0; x < w; x++) {
unsigned u = s[x]*a[x] + target*(255-a[x]) + 128;
unsigned u = s[x]*a[x] + target_table[((x^y)>>5)&1][plane]*(255-a[x]) + 128;
d[x] = (257*u) >> 16;
}
}
@ -84,7 +89,7 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
for (x = 0; x < w; x++) {
for (plane = 0; plane < plane_count; plane++) {
int x_index = (plane_count + 1) * x;
unsigned u = s[x_index + plane]*a[x_index] + target_table[plane]*(max-a[x_index]) + off;
unsigned u = s[x_index + plane]*a[x_index] + target_table[((x^y)>>5)&1][plane]*(max-a[x_index]) + off;
d[plane_count*x + plane] = av_clip((u + (u >> shift)) >> shift, 0, max);
}
}
@ -93,7 +98,7 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
for (plane = 0; plane < plane_count; plane++) {
int x_index = (plane_count + 1) * x;
unsigned aswap =av_bswap16(a[x_index]);
unsigned u = av_bswap16(s[x_index + plane])*aswap + target_table[plane]*(max-aswap) + off;
unsigned u = av_bswap16(s[x_index + plane])*aswap + target_table[((x^y)>>5)&1][plane]*(max-aswap) + off;
d[plane_count*x + plane] = av_clip((u + (u >> shift)) >> shift, 0, max);
}
}
@ -105,7 +110,7 @@ int ff_sws_alphablendaway(SwsContext *c, const uint8_t *src[],
for (x = 0; x < w; x++) {
for (plane = 0; plane < plane_count; plane++) {
int x_index = (plane_count + 1) * x;
unsigned u = s[x_index + plane]*a[x_index] + target_table[plane]*(255-a[x_index]) + 128;
unsigned u = s[x_index + plane]*a[x_index] + target_table[((x^y)>>5)&1][plane]*(255-a[x_index]) + 128;
d[plane_count*x + plane] = (257*u) >> 16;
}
}

1
libswscale/options.c
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@ -81,6 +81,7 @@ static const AVOption swscale_options[] = {
{ "alphablend", "mode for alpha -> non alpha", OFFSET(alphablend),AV_OPT_TYPE_INT, { .i64 = SWS_ALPHA_BLEND_NONE}, 0, SWS_ALPHA_BLEND_NB-1, VE, "alphablend" },
{ "none", "ignore alpha", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_ALPHA_BLEND_NONE}, INT_MIN, INT_MAX, VE, "alphablend" },
{ "uniform_color", "blend onto a uniform color", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_ALPHA_BLEND_UNIFORM},INT_MIN, INT_MAX, VE, "alphablend" },
{ "checkerboard", "blend onto a checkerboard", 0, AV_OPT_TYPE_CONST, { .i64 = SWS_ALPHA_BLEND_CHECKERBOARD},INT_MIN, INT_MAX, VE, "alphablend" },
{ NULL }
};

1
libswscale/swscale_internal.h
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@ -78,6 +78,7 @@ typedef enum SwsDither {
typedef enum SwsAlphaBlend {
SWS_ALPHA_BLEND_NONE = 0,
SWS_ALPHA_BLEND_UNIFORM,
SWS_ALPHA_BLEND_CHECKERBOARD,
SWS_ALPHA_BLEND_NB,
} SwsAlphaBlend;