This involves multiple changes:
1. Brightness metadata is split into nominal peak and signal peak.
For a quick and dirty explanation: nominal peak is the brightest value
that your color space can represent (i.e. the brightness of an encoded
1.0), and signal peak is the brightest value that actually occurs in
the video (i.e. the brightest thing that's displayed).
2. vo_opengl uses a new decision logic to figure out the right nom_peak
and sig_peak for all situations. It also does a better job of picking
the right target gamut/colorspace to use for the OSD. (Which still is
and still should be treated as sRGB). This change in logic also
fixes#3293 en passant.
3. Since it was growing rapidly, the logic for auto-guessing / inferring
the right colorimetry configuration (in pass_colormanage) was split from
the logic for actually performing the adaptation (now pass_color_map).
Right now, the new logic doesn't do a whole lot since HDR metadata is
still ignored (but not for long).
Instead of doing HDR tone mapping on an ad-hoc basis inside
pass_colormanage, the reference peak of an image is now part of the
image params (alongside colorspace, gamma, etc.) and tone mapping is
done whenever peak_src != peak_dst.
To get sensible behavior when mixing HDR and SDR content and displays,
target-brightness is a generic filler for "the assumed brightness of SDR
content".
This gets rid of the weird display_scaled hack, sets the framework
for multiple HDR functions with difference reference peaks, and allows
us to (in a future commit) autodetect the right source peak from
the HDR metadata.
(Apart from metadata, the source peak can also be controlled via
vf_format. For HDR content this adjusts the overall image brightness,
for SDR content it's like simulating a different exposure)
This is now a configurable option, with tunable parameters.
I got inspiration for these algorithms off wikipedia. "simple" seems to
work pretty well, but not well enough to make it a reasonable default.
Some other notable candidates:
- Local functions (e.g. based on local contrast or gradient)
- Clamp with soft knee (linear up to a point)
- Mapping in CIE L*Ch. Map L smoothly, clamp C and h.
- Color appearance models
These will have to be implemented some other time.
Note that the parameter "peak_src" to pass_tone_map should, in
principle, be auto-detected from the SEI information of the source file
where available. This will also have to be implemented in a later
commit.
This macro takes care of rotation, swizzling, integer conversion and
normalization automatically. I found the performance impact to be
nonexistant for superxbr and debanding, although rotation *did* have an
impact due to the extra matrix multiplication. (So it gets skipped where
possible)
All of the internal hooks have been rewritten to use this new mechanism,
and the prescaler hooks have finally been separated from each other.
This also means the prescale FBO kludge is no longer required.
This fixes image corruption for image formats like 0bgr, and also fixes
prescaling under rotation. (As well as other user hooks that have
orientation-dependent access)
The "raw" attributes (tex, tex_pos, pixel_size) are still un-rotated, in
case something needs them, but ideally the hooks should be rewritten to
use the new API as much as possible. The hooked texture has been renamed
from just NAME to NAME_raw to make script authors notice the change (and
also deemphasize direct texture access).
This is also a step towards getting rid of the use_integer pass.
These are "sequence points" where the image could be rendered out to an
FBO, hooked, and re-loaded if any such hook exists. This is perfect for
things like the current user shaders system, as well as optional effects
like unsharp masking.
Note that since we have to pick *some* FBO to store the optionally
hooked texture, we just store it in an array indexed by an increasing
counter. Since we only ever store as many as MAX_TEXTURE_HOOKS + all
internal hook points entries, this is guaranteed to be enough space.
This commit also removes some of the now unused FBOs.
This is a pretty major rewrite of the internal texture binding
mechanic, which makes it more flexible.
In general, the difference between the old and current approaches is
that now, all texture description is held in a struct img_tex and only
explicitly bound with pass_bind. (Once bound, a texture unit is assumed
to be set in stone and no longer tied to the img_tex)
This approach makes the code inside pass_read_video significantly more
flexible and cuts down on the number of weird special cases and
spaghetti logic.
It also has some improvements, e.g. cutting down greatly on the number
of unnecessary conversion passes inside pass_read_video (which was
previously mostly done to cope with the fact that the alternative would
have resulted in a combinatorial explosion of code complexity).
Some other notable changes (and potential improvements):
- texture expansion is now *always* handled in pass_read_video, and the
colormatrix never does this anymore. (Which means the code could
probably be removed from the colormatrix generation logic, modulo some
other VOs)
- struct fbo_tex now stores both its "physical" and "logical"
(configured) size, which cuts down on the amount of width/height
baggage on some function calls
- vo_opengl can now technically support textures with different bit
depths (e.g. 10 bit luma, 8 bit chroma) - but the APIs it queries
inside img_format.c doesn't export this (nor does ffmpeg support it,
really) so the status quo of using the same tex_mul for all planes is
kept.
- dumb_mode is now only needed because of the indirect_fbo being in the
main rendering pipeline. If we reintroduce p->use_indirect and thread
a transform through the entire program this could be skipped where
unnecessary, allowing for the removal of dumb_mode. But I'm not sure
how to do this in a clean way. (Which is part of why it got introduced
to begin with)
- It would be trivial to resurrect source-shader now (it would just be
one extra 'if' inside pass_read_video).
Do this to make the license situation less confusing.
This change should be of no consequence, since LGPL is compatible with
GPL anyway, and making it LGPL-only does not restrict the use with GPL
code.
Additionally, the wording implies that this is allowed, and that we can
just remove the GPL part.
This turns the old scalers (inherited from MPlayer) into a pre-
processing step (after color conversion and before scaling). The code
for the "sharpen5" scaler is reused for this.
The main reason MPlayer implemented this as scalers was perhaps because
FBOs were too expensive, and making it a scaler allowed to implement
this in 1 pass. But unsharp masking is not really a scaler, and I would
guess the result is more like combining bilinear scaling and unsharp
masking.
2 things are being stupid here: Apple for requiring rectangle textures
with their IOSurface interop for no reason, and OpenGL having a
different sampler type for rectangle textures.
The removal of source-shader is a side effect, since this effectively
replaces it - and the video-reading code has been significantly
restructured to make more sense and be more readable.
This means users no longer have to constantly download and maintain a
separate deband.glsl installation alongside mpv, which was the only real
use case for source-shader that we found either way.
This is mostly to cut down somewhat on the amount of code bloat in
video.c by moving out helper functions (including scaler kernels and
color management routines) to a separate file.
It would certainly be possible to move out more functions (eg. dithering
or CMS code) with some extra effort/refactoring, but this is a start.
Signed-off-by: wm4 <wm4@nowhere>
Niklas Haas
wm4
igv