Fix certain animated PNGs returning NaN as the duration because the
frame rate was being reported as "0/0" by FFMpeg. This happens when the
animation has zero delay between frames. This is supposed to mean a PNG
with an infinitely fast frame rate, but in practice browsers limit it to
around 10FPS. The exact frame rate browsers will use is unknown and
implementation defined.
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.
Rotate the image based on the EXIF orientation flag when generating
thumbnails and samples.
Also fix the width and height to be calculated correctly for rotated
images. Vips gives us the unrotated width and height of the image; we
have to detect whether the image is rotated and swap the width and
height manually to correct them. For example, if an image with the
"Rotate 90 CW" flag is 100x500 before rotation, then after rotation it's
500x100. This should fix#4883 (Exif rotation breaks Javascript fit-to-window)
We also have to fix it so that regenerating a post updates the width and
height of the post, in the event that it's a rotated image.
Finally we set `image-orientation: from-image;` even though it's
probably not necessary.
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.
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.
* Fix corrupted image detection. We were shelling out to vips and trying
to grep for error messages, but the error message for jpeg files changed.
Now we load the file in ruby vips, which raises an error on failure.
* Don't attempt to redownload corrupted images. If a download completes
without any errors yet the downloaded file is corrupt, then something is
wrong at the source and redownloading is unlikely to help. Let the
upload fail and the user retry if necessary.
* Validate that all uploads are uncorrupted, including files uploaded
from a computer, not just files uploaded from a source.
