It differs from query_func() in accepting arrays of input/output format
configurations to be filled as callback parameters. This allows to mark
the filter context as const, ensuring it is not modified by this
function, as it is not supposed to have any side effects beyond
returning the supported formats.
The color range should be set to match the input when creating
the VideoToolbox context. Otherwise, the new context will default
to limited range, creates inconsistencies with full range inputs.
Signed-off-by: Gnattu OC <gnattuoc@me.com>
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
The only thing this function does beyond calling av_get_pix_fmt() is
falling back onto parsing the argument as a number. No other filters
should need to do this.
The current logic hard-coded a check for v_sub == 1. We can extend this
logic slightly to cover the case of interlaced 4:1:0 (which has v_sub ==
2).
Here is a diagram explaining this scenario (with center-siting):
a a a a a a a a
b b b b b b b b
X X
a a a a a a a a
b b b b b b b b
a a a a a a a a
b b b b b b b b
Y Y
a a a a a a a a
b b b b b b b b
a = even luma rows
b = odd luma rows
X = even chroma sample
Y = odd chroma sample
In progressive mode, the chroma samples sit at (384, 384) respectively.
Relative to the 8x4 grid of even luma samples (a), the X sample sits at:
h_chr_pos = 384
v_chr_pos = 192
Relative to the 8x4 grid of odd luma samples (b), the Y sample sits at:
h_chr_pos = 384
v_chr_pos = 576
The new code calculates the correct values in all circumstances.
Currently, this just functions as a more principled and user-friendly
replacement for the (undocumented and hard to use) *_chr_pos fields.
However, the goal is to automatically infer these values from the input
frames' chroma location, and deprecate the manual use of *_chr_pos
altogether. (Indeed, my plans for an swscale replacement will most
likely also end up limiting the set of legal chroma locations to those
permissible by AVFrame properties)
The current logic only fixes it when the user does not explicitly
specify the chroma location. However, this does not make a lot of sense.
Since there is no way to specify this property per-field, it effectively
*prevents* the user from being able to correctly scale interlaced frames
with top-aligned chroma.
It makes more sense to consider the user setting in the progressive case
only, and automatically adapt it to the correct interlaced field
positions, following the details of the MPEG specification.
We check for whether subformats support storage immediately below.
Those are the ones we require storage for, rather than the base format
itself.
This permits better reuse of AVHWFrame contexts.
The patch also removes an always-false check in the subformat check.
Vulkan encoding was designed in a very... consolidated way.
You had to know the exact codec and profile that the image was going to
eventually be encoded as at... image creation time. Unfortunately, as good
as our code is, glimpsing into the exact future isn't what its capable of.
video_maintenance1 removed that requirement, which only then made encoding
images practically possible.
