Start storing the duration of animations and videos in the `duration`
field on the media_assets table. This had to wait until 3d30bfd69 was
deployed, which had to wait until Postgres was upgraded in order to add
the duration column to the media_assets table without downtime.
Also add a fix script to backfill the duration on existing posts. Usage:
TAGS=animated ./script/fixes/079_fix_duration.rb
Move the metadata parsing code from MediaAsset to ExifTool::Metadata so
we can use it outside the context of a MediaAsset, in particular when
dealing with a MediaFile that hasn't been saved to disk yet.
Fix a bug where where PNG images could be incorrectly detected as
exif-rotated. This would happen when a PNG contained the
IFD0:Orientation flag. It's technically possible for a PNG to contain
this flag, but it's ignored by libvips and by browsers.
post #3762340 (nsfw) is an example of a PNG like this.
The fix is to use `autorot` to let libvips apply the rotation instead of
trying to interpret the exif data ourselves. Note that libvips-8.9 has a
bug where it doesn't strip the orientation flag after applying
`autorot`, which leads to the image being incorrectly rotated a second
time when generating the thumbnail. Use libvips-8.11 instead.
`IFD0:Orientation` is the orientation of the main image.
`IFD1:Orientation` is the orientation of the embedded thumbnail, if it
has one. Using `IFD1:Orientation` was incorrect here because some images
have a non-rotated main image but a rotated thumbnail. Post #1023563 is
an example.
Autotag `greyscale`, `non-repeating_animation`, and `exif_rotation`.
Note that this does not detect all (or even most) greyscale images.
Artists often save greyscale images as RGB instead of as greyscale.
Automatically tag animated_gif and animated_png when a post is edited.
Add them back if the user tries to remove them from an animated post,
or remove them if the user tries to add them to a non-animated post.
Before we added these tags at upload time, but it was possible for users
to remove them after upload, or to incorrectly add them to non-animated
posts. They were added at upload time because we couldn't afford to open
the file and parse the metadata on every tag edit. Now that we save the
metadata in the database, we can do this.
This also makes it so you can't tag ugoira on non-ugoira files.
Known bug: it's possible to have an animated GIF where every frame is
identical. Post #3770975 is an example. This will be detected as an
animated GIF even though visually it doesn't appear to be animated.
Fixes#4041: Animated_gif tag not added to preprocessed uploads
Add a model for storing image and video metadata for uploaded files.
Metadata is extracted using ExifTool. You will need to install ExifTool
after this commit. ExifTool 12.22 is the minimum required version
because we use the `--binary` option, which was added in this release.
The MediaMetadata model is separate from the MediaAsset model because
some files contain tons of metadata, and most of it is non-essential.
The MediaAsset model represents an uploaded file and contains essential
metadata, like the file's size and type, while the MediaMetadata model
represents all the other non-essential metadata associated with a file.
Metadata is stored as a JSON column in the database.
ExifTool returns all the file's metadata, not just the EXIF metadata.
EXIF is one of several types of image metadata, hence why we call
it MediaMetadata instead of EXIFMetadata.
A MediaAsset represents an image or video file uploaded to Danbooru. It
stores the metadata associated with the image or video. This is to work
on decoupling files from posts so that images can be uploaded separately
from posts.
