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video: overlay-composition: try to avoid floating point maths in inner loop

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Try to avoid floating point maths for each pixel to be blended in
inner loop, and try to avoid the multiplication entirely for the
most common case of the global alpha being 1. Could probably be
refactored a bit more.
This commit is contained in:
Tim-Philipp Müller 2012-03-25 00:22:29 +00:00
parent 32679e1826
commit 79953f27a8
1 changed files with 28 additions and 14 deletions
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42
gst-libs/gst/video/video-blend.c
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@ -1342,16 +1342,16 @@ gboolean
video_blend (GstBlendVideoFormatInfo * dest,
GstBlendVideoFormatInfo * src, guint x, guint y, gfloat global_alpha)
{
guint i, j;
guint8 alpha;
guint i, j, global_alpha_val;
GetPutLine getputdest, getputsrc;
gint src_stride;
guint8 *tmpdestline = NULL, *tmpsrcline = NULL;
gboolean src_premultiplied_alpha;
g_return_val_if_fail (dest, FALSE);
g_return_val_if_fail (src, FALSE);
g_return_val_if_fail (global_alpha >= 0 && global_alpha <= 1, FALSE);
g_assert (dest != NULL);
g_assert (src != NULL);
global_alpha_val = 256.0 * global_alpha;
/* we do no support writing to premultiplied alpha, though that should
just be a matter of adding blenders below (BLEND01 and BLEND11) */
@ -1414,10 +1414,12 @@ video_blend (GstBlendVideoFormatInfo * dest,
/* Here dest and src are both either in AYUV or ARGB
* TODO: Make the orc version working properly*/
#define BLENDLOOP(blender) \
#define BLENDLOOP(blender,alpha_val,alpha_scale) \
do { \
for (j = 0; j < src->width * 4; j += 4) { \
alpha = (guint8) tmpsrcline[j] * global_alpha; \
guint8 alpha; \
\
alpha = (tmpsrcline[j] * alpha_val) / alpha_scale; \
\
blender (tmpdestline[j + 1], alpha, tmpsrcline[j + 1], tmpdestline[j + 1]); \
blender (tmpdestline[j + 2], alpha, tmpsrcline[j + 2], tmpdestline[j + 2]); \
@ -1425,14 +1427,26 @@ video_blend (GstBlendVideoFormatInfo * dest,
} \
} while(0)
if (src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND11); */
} else if (!src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND01); */
} else if (src_premultiplied_alpha && !dest->premultiplied_alpha) {
BLENDLOOP (BLEND10);
if (G_LIKELY (global_alpha == 1.0)) {
if (src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND11, 1, 1); */
} else if (!src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND01, 1, 1); */
} else if (src_premultiplied_alpha && !dest->premultiplied_alpha) {
BLENDLOOP (BLEND10, 1, 1);
} else {
BLENDLOOP (BLEND00, 1, 1);
}
} else {
BLENDLOOP (BLEND00);
if (src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND11, global_alpha_val, 256); */
} else if (!src_premultiplied_alpha && dest->premultiplied_alpha) {
/* BLENDLOOP (BLEND01, global_alpha_val, 256); */
} else if (src_premultiplied_alpha && !dest->premultiplied_alpha) {
BLENDLOOP (BLEND10, global_alpha_val, 256);
} else {
BLENDLOOP (BLEND00, global_alpha_val, 256);
}
}
#undef BLENDLOOP