Bug: if ExifTool exited with status 1 because it thought the file was
corrupt, then we didn't record any of the metadata, even though it was
able to read most of it. It turns out there are thousands of posts with
minorly corrupt metadata that ExifTool is still able to read, but will
complain about.
Fix: ignore the exit code of ExifTool and always save whatever metadata
ExifTool is able to return. It will return an `ExifTool:Error` tag in
the event of errors.
Note that there are some (many?) files that are considered corrupt by
ExifTool but not by Vips, and vice versa. Probably because ExifTool only
parses the metadata while Vips only parses the image data.
Fix Exiftool not being able to get the metadata for compressed SWF
files. Exiftool requires Compress::Zlib as an optional dependency to
decompress compressed SWF files, but it wasn't in the Docker image.
Archive::Zip is required for Zip files and Digest::MD5 for certain other
metadata (see "DEPENDENCIES" in exiftool README).
Fix a bug where generating thumbnails failed for certain images when
using libvips 8.10. Specifically, it failed for single-channel greyscale
images and four-channel CMYK images without an embedded color profile.
In these cases we specified an sRGB fallback profile, but under libvips
8.10 this failed because the sRGB profile was incompatible with
single-channel and four-channel images. Before libvips 8.10 this worked,
but as of 8.10 it's a hard error.
The way libvips handles fallback color profiles differs across versions,
so we have to use different arguments for different versions. In 8.7,
vips doesn't have builtin color profiles, so we have to specify our own
manually. In 8.9, it has builtin profiles, so we can omit the import
profile, but we're still required to set the export profile to sRGB,
otherwise it will leave CMYK images as CMYK when generating thumbnails.
In 8.10, we have to _not_ to set the import or export profile to sRGB,
otherwise it will fail with an incompatible profile error when it tries
to convert CMYK images to RGB.
The builtin sRGB profile used by libvips[1] is different than the one we
used previously[2]. The builtin one comes from LCMS[3], whereas ours
came from ArgyllCMS.[4] Not all sRGB profiles are created the same[5],
so this may result in some imperceptible differences in thumbnail
output. The ArgyllCMS profile was used before because it seemed to be
the best one[6], but realistically it probably doesn't matter.
1: https://github.com/libvips/libvips/blob/v8.10.6/libvips/colour/profiles/sRGB.icm
2: 906eec190d/config/sRGB.icm
3: https://www.littlecms.com/
4: https://www.argyllcms.com/
5: https://ninedegreesbelow.com/photography/srgb-profile-comparison.html
6: https://ninedegreesbelow.com/photography/srgb-profile-comparison.html#addendum
Fix regression in ef2857667 that caused animated GIFs and PNGs to
generate thumbnails that were larger than 150x150.
Also fix a bug with cropped previews not being generated for animated
GIFs and PNGs.
* Move image thumbnail generation code to MediaFile::Image.
* Move video thumbnail generation code to MediaFile::Video.
* Move ugoira->webm conversion code to MediaFile::Ugoira.
This separates thumbnail generation from the upload process so that it's
possible to generate thumbnails outside of uploads.
* Add MediaFile abstraction. A MediaFile represents an image or video file.
* Move filetype detection and dimension parsing code from uploads to MediaFile.
