It may be completely useless, and I can't verify it as no known samples
or other known/accessible software using it, but why not?
Putting this together with he 422 code requires making it slightly more
generic. I'm still staying with a "huge" if tree instead of a table to
select the scanline worker callback, because it's actually small and not
huge (although it not being generic still feels slightly painful).
Remove the vaguely defined plane_bits and component_bits fields from
struct mp_imgfmt_desc. Add weird replacements for existing uses. Remove
the bytes[] field, replace uses with bpp[].
Fix some potential alignment issues in existing code. As a compromise,
split mp_image_pixel_ptr() into 2 functions, because I think it's a bad
idea to implicitly round, but for some callers being slightly less
strict is convenient.
This shouldn't really change anything. In fact, it's a 100% useless
change. I'm just cleaning up what I started almost 8 years ago (see
commit 00653a3eb0). With this I've decided to keep mp_imgfmt_desc,
just removing the weird parts, and keeping the saner parts.
This checked params->color.space for being RGB. If the colorspace is
unset, this did dumb things because even if the imgfmt was a RGB one,
the colorspace was not set to RGB. This actually also happened to the
tests.
(Short-cutting RGB like this is actually wrong, since RGB could still
have strange gamma or primaries, which would warrant a full conversion.
So you'd need to check for these other parameters as well. To be fixed
later.)
Maybe this is useful for some of the lesser VOs. It's preferable over
bad ad-hoc solutions based on the more complex sub_bitmap data
structures (as observed e.g. in vo_vaapi.c), and does not use that much
more code since draw_bmp already created such an overlay internally.
But I still wanted something that avoids having to upload/render a full
screen-sized overlay if for example there's only a tiny subtitle line on
the bottom of the screen. So the new API can return a list of modified
pixels (for upload) and non-transparent pixels (for display). The way
these pixel rectangles are computed is a bit dumb and returns dumb
results, but it should be usable, and the implementation can change.
draw_bmp.c is the software blender for subtitles and OSD. It's used by
encoding mode (burning subtitles), and some VOs, like vo_drm, vo_x11,
vo_xv, and possibly more.
This changes the algorithm from upsampling the video to 4:4:4 and then
blending to downsampling the OSD and then blending directly to video.
This has far-reaching consequences for its internals, and results in an
effective rewrite.
Since I wanted to avoid un-premultiplying, all blending is done with
premultiplied alpha. That's actually the sane thing to do. The old code
just didn't do it, because it's very weird in YUV fixed point.
Essentially, you'd have to compensate for the chroma centering constant
by subtracting src_alpha/255*128. This seemed so hairy (especially with
correct rounding and high bit depths involved) that I went for using
float.
I think it turned out mostly OK, although it's more complex and less
maintainable than before. reinit() is certainly a bit too long. While it
should be possible to optimize the RGB path more (for example by
blending directly instead of doing the stupid float conversion), this is
probably slower. vo_xv users probably lose in this, because it takes the
slowest path (due to subsampling requirements and using YUV).
Why this rewrite? Nobody knows. I simply forgot the reason. But you'll
have it anyway. Whether or not this would have required a full rewrite,
at least it supports target alpha now (you can for example hard sub
transparent PNGs, if you ever wanted to use mpv for this).
Remove the check in vf_sub. The new draw_bmp.c is not as reliant on
libswscale anymore (mostly uses repack.c now), and osd.c shows an
error message on missing support instead now.
Formats with chroma subsampling of 4 are not supported, because FFmpeg
doesn't provide pixfmt definitions for alpha variants. We could provide
those ourselves (relatively trivial), but why bother.
Was broken with a zimg wrapper refucktor before the previous commit. In
addition, it seems this didn't match the vo_drm format, or the format
naming convention. So the order actually changes, and the format is
redefined. (The img_format.h comment was probably wrong.)
Change vo_gpu to the new format as well, so we can still test it.
For whatever purpose. If anything, this makes the zimg wrapper cleaner.
The added tests are not particular exhaustive, but nice to have. This
also makes the scale_zimg.c test pretty useless, because it only tests
repacking (going through the zimg wrapper). In theory, the repack_tests
things could also be used on scalers, but I guess it doesn't matter.
Some things are added over the previous zimg wrapper code. For example,
some fringe formats can now be expanded to 8 bit per component for
convenience.
wm4