On 01.08.2017 15:31, Paul B Mahol wrote:
On 8/1/17, Tobias Rapp <t.r...@noa-archive.com> wrote:
On 01.08.2017 13:03, Paul B Mahol wrote:
Signed-off-by: Paul B Mahol <one...@gmail.com>
---
doc/filters.texi | 13 ++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_premultiply.c | 307
++++++++++++++++++++++++++++++++++++-------
4 files changed, 277 insertions(+), 45 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 4089135..a50696a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -14532,6 +14532,19 @@ ffmpeg -i INPUT -vf trim=duration=1
@end itemize
+@section unpremultiply
+Apply alpha unpremultiply effect to input video stream using first plane
+of second stream as alpha.
+
+Both streams must have same dimensions and same pixel format.
+
+The filter accepts the following option:
+
+@table @option
+@item planes
+Set which planes will be processed, unprocessed planes will be copied.
+By default value 0xf, all planes will be processed.
+@end table
IMHO using a flags-like string "planes=rgb" would be more user-friendly
than a bitmask. At least the documentation should tell which bit refers
to what channel.
It is directly related to pixel format.
I'm just wondering whether I can apply the logic of
AVPixFmtDescriptor.comp to the planes bitmask or not:
/**
* Parameters that describe how pixels are packed.
* If the format has 1 or 2 components, then luma is 0.
* If the format has 3 or 4 components:
* if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
* otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
*
* If present, the Alpha channel is always the last component.
*/
Regards,
Tobias
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