ASS Format: Introduce LayoutRes{X,Y} script headers #39
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It is only used from the member function RenderEx(...) and being able to rely on it not being used from the outside simplifies the next commit. Deinit(..) has users outside the class, but is also not relevant for the planned change.
Rendering ASS depends on the video’s storage resolution
for several tags. Thus transferring a subtitle file to a
different version of a video, with e.g. higher resolution
or anamorphic squeezing undone, requires adjusting all those
tags.
Affected are \be, \blur, \frx, \fry and if ScaledBorderAndShadow
is not set to "yes", also all tags related to border and shadow.
This locks all but simple subtitle files to a specific video
storage resolution. If one wants to release several different resolution
simultaneously, the same source is reencoded to undo anamorphic
squeezing, or a new higher resolution source appears, it is required
to manually adjust affected tags and each video version needs a
different subtitle file.
This is a pain point, and resulted in some releases just
relying on user overrides of players, or incompatibly patched
renderers to avoid the required manual adjustments.
By adding new headers, which will replace the original video storage
resolution in all calculations, authors will be able to create files
which can be reused across different resolutions as long as the display
aspect ratio stays the same. Hopefully this will also halt the spread of
incomapatible patches and overrides, which just result in broken files
and further ASS fragmentation.
For simplicity and to avoid surprises, LayoutRes* headers
only take effect if both are present and set to values larger
than zero.
If LayoutRes{X,Y} is set to corresponds to the actual storage resolution
of the video the subs are authored and initially released with, at least
the initial/main version will also be effectively compatible to older
renderers, which do not understand the new headers yet. This will grant
users some time to upgrade and minimise friction from this retroactive
format addition.
The header's introduction is coordinated with other renderers,
so that they'll be widely available amongt still maintain ASS
implementations.
As a followup, integration into active Aegisub forks
and other common editors will also be pursued.
Regarding the implementation in xy-VSFilter/xySubFilter:
To find out where the video storage resolution is used,
I followed the "originalVideoSize" field from include/SubRenderIntf.h
to RTS.cpp. The property is however, also used in a bunch of places
outside of src/subtitles. As I have no knowledge of those areas,
I didn't change anything there, but it seems unlikely - and prelimanry
testing seems to agree - that those have any effect on ASS rendering.
To make it easy to spot the actual functional changes,
the old original_video_size name was kept for most parts.
A follow-up patch will do cosmetic-only renaming.
Since it can now be overriden by script headers, the old name became misleading.
Without this the build cannot find yasm.exe. Adjustments copied from xy-VSFilter-with-libass found here: https://github.com/Masaiki/xy-VSFilter. It is not tested on a local VS setup, because I don't have one.
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Hi, can you share binary?? |
TheOneric
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xy-VSFilter builds may have subtle bugs, see #38. So if you want xy-VSFilter with |
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But can't pull request layout res to my fork. I want creat my binary myself |
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@TheOneric Do you plan to make a fork with pinterf updates, but with the updated vsfilters patches that are missing here? (And with the fixes in this pull request too) |
YOu don't need pull requests for pushing to your own repo. You only need to enable GitHub Actions if it isn’t already (click the “Actions” tab) and directly push the relevant commits to a suitable branch like
If the question is whether I’ll create a It hasn't even been two days yet since I opened this PR, so let’s just wait until @pinterf finds some time to look at and merge this. |
Backport of Cyberbeing/xy-VSFilter#18 (see also: Cyberbeing/xy-VSFilter#19); the header was also introduced in libass and released as part of libass 0.17.0 about a month ago and clsid2 also works on implementing this in MPC-HC’s ISR.
In a sense also a follow up to #34.