Without resetting it, if there was a previous set of varstreams with
subtitles, it would subtract from all the streams, leading to chaos and
segfaults when trying to access for example stream -1.
In the absence of an RPU header, we can consult the colorspace tags to
make a more informed guess about whether we're looking at profile 5 or
profile 8.
This implements limited metadata compression. To be a bit more lenient,
we try and re-order the static extension blocks when testing for an
exact match.
For sanity, and to avoid producing bitstreams we couldn't ourselves
decode, we don't accept partial matches - if some extension blocks
change while others remain static, compression is disabled for the
entire frame.
This shouldn't be an issue in practice because static extension blocks
are stated to remain constant throughout the entire sequence.
This implements the limited DM metadata compression scheme described in
chapter 9 of the dolby vision bitstream specification.
The spec is a bit unclear about how to handle the presence of static
metadata inside compressed frames; in that it doesn't explicitly forbid
an encoder from repeating redundant metadata. In theory, we would need
to detect this case and then strip the corresponding duplicate metadata
from the existing set of static metadata. However, this is difficult to
implement - esspecially for the case of metadata blocks which may be
internally repeated (e.g. level 10).
That said, the spec states outright that static metadata should be
constant throughout the entire sequence, so a sane bitstream should not
have any static metadata values changing from one frame to the next (at
least up to a keyframe boundary), and therefore they should never be
present in compressed frames. As a consequence, it makes sense to treat
this as an error state regardless. (Ignoring them by default, or
erroring if either AV_EF_EXPLODE or AV_EF_AGGRESSIVE are set)
I was not able to find such samples in the wild (outside of artificially
produced test cases for this exact scenario), so I don't think we need
to worry about it until somebody produces one.
Keyframes must reset the metadata compression state, so we need to
also signal this at rpu generation time.
Default to uncompressed, because encoders cannot generally know if
a given frame will be a keyframe before they finish encoding, but also
cannot retroactively attach the RPU. (Within the confines of current
APIs)
And move the choice of desired container to `flags`. This is needed to
handle differing API requirements (e.g. libx265 requires the NAL RBSP,
but CBS BSF requires the unescaped bytes).
Limited mode can only ever maintain a single VDR RPU reference, and
furthermore requires vdr_rpu_id == 0. So in practice, it will only ever
use VDR RPU slot 0. All remaining slots get flushed in this case, to
avoid leaking partial state.
As the comment implies, DOVIContext.ext_blocks should also reflect the
current state after ff_dovi_rpu_generate().
Fluff for now, but will be needed once we start implementing metadata
compression for extension blocks as well.
Replace the manually specified chroma location by one using standard
notation, arbitrarily "bottomleft" as it is a less common path.
Required if we want to phase out the use of manual chroma locations.
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.
When dealing with 4x subsampling ratios (log2 == 2), such as can arise
with 4:1:1 or 4:1:0, a value range of 512 is not enough to cover the
range of possible scenarios.
For example, bottom-sited chroma in 4:1:0 would require an offset of 768
(three luma rows). Simply double the limit to 1024. I don't see any
place in initFilter() that would experience overflow as a result of this
change, especially since get_local_pos() right-shifts it by the
subsampling ratio again.
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.
The issue is that enabling features requires that the device
extension is supported. The extensions bitfield was set later,
so it was always 0, leading to no features being added.
The validation layer option only supported GPU-assisted validation.
This is mutually exclusive with shader debug printfs, so we need to
differentiate between the two.
This also fixes issues with user-given layers, and leaks in case of
errors.
Specifically those that should be visible to filters, but hidden from
API callers. Such properties are currently located at the end of the
public AVFilterLink struct, demarcated by a comment marking them as
private. However it is generally better to hide them explicitly, using
the same pattern already employed in avformat or avcodec.
The new struct is currently trivial, but will become more useful in
following commits.
