Animated APNG stickers with palette are not animated
romainricard opened this issue · comments
- I have searched open and closed issues for duplicates
- I am submitting a bug report for existing functionality that does not work as intended
- This isn't a feature request or a discussion topic
Bug description
Some animated APNG stickers are not animated on Signal for iOS. While digging, I realized that the common thread between faulty stickers is that they contain a palette (i.e. PNG with a tRNS chunck).
Having a palette is very important for animated stickers, as it allows to save a lot of weight, thus allowing stickers with higher resolution/more frames to be uploaded.
Note that APNG stickers with palette do work on Signal on all other platforms.
Here are some examples:
Demo sticker with palette
This sticker is not animated on iOS. ❌
https://signal.art/addstickers/#pack_id=b020b5f29795e931cf11c4450d12ebca&pack_key=f2a19052ed4077ffbe59d7374a6a7ed7e433854abb5b5844f0af5eaf3c7f5ade
% pngcheck sticker_with_palette.png
OK: sticker_with_palette.png (304x304, 8-bit palette+trns, non-interlaced, 24.4%).
% du -h sticker_with_palette.png
72K sticker_with_palette.png
Demo sticker without palette (RGB)
This sticker is animated on iOS. ✔️
https://signal.art/addstickers/#pack_id=f30476e7bab76d9b73c289c97bc6fdb4&pack_key=0bb6189c1c7ab04b56a3aa59a69de5101a4a6b0dec54cc3c880732b7be7546d7
% pngcheck sticker_rgb.png
OK: sticker_rgb.png (300x300, 32-bit RGB+alpha, non-interlaced, 67.4%).
% du -h sticker_rgb.png
116K sticker_rgb.png
Example pack containing both with and without palette stickers
This pack's only sticker that is animated on iOS is the one without a palette:
% pngcheck *.png OK: 0.png (270x300, 8-bit palette+trns, non-interlaced, 91.5%). OK: 1.png (320x300, 8-bit palette+trns, non-interlaced, 90.3%). OK: 2.png (334x300, 8-bit palette+trns, non-interlaced, 81.7%). OK: 3.png (370x300, 8-bit palette+trns, non-interlaced, -13.6%). OK: 4.png (270x300, 32-bit RGB+alpha, non-interlaced, 91.7%). OK: 5.png (270x300, 8-bit palette+trns, non-interlaced, 82.1%). OK: 6.png (270x300, 8-bit palette+trns, non-interlaced, 84.0%). OK: 7.png (300x300, 8-bit palette+trns, non-interlaced, 90.7%). OK: 8.png (320x300, 8-bit palette+trns, non-interlaced, -6.7%). OK: 9.png (270x300, 8-bit palette+trns, non-interlaced, 91.3%). OK: 10.png (270x300, 8-bit palette+trns, non-interlaced, 89.9%). OK: 11.png (280x300, 8-bit palette+trns, non-interlaced, 63.4%). OK: 12.png (270x300, 8-bit palette+trns, non-interlaced, 76.4%). OK: 13.png (280x300, 8-bit palette+trns, non-interlaced, 59.6%). OK: 14.png (270x300, 8-bit palette+trns, non-interlaced, 71.4%). OK: 15.png (270x300, 8-bit palette+trns, non-interlaced, 89.3%). OK: 16.png (300x300, 8-bit palette+trns, non-interlaced, 68.3%). OK: 17.png (270x300, 8-bit palette+trns, non-interlaced, 73.5%). OK: 18.png (280x300, 8-bit palette+trns, non-interlaced, 59.7%). OK: 19.png (290x300, 8-bit palette+trns, non-interlaced, 68.0%). OK: 20.png (270x300, 8-bit palette+trns, non-interlaced, 42.6%). OK: 21.png (300x300, 8-bit palette+trns, non-interlaced, 69.8%). OK: 22.png (270x300, 8-bit palette+trns, non-interlaced, 50.6%). OK: 23.png (270x300, 8-bit palette+trns, non-interlaced, 86.7%). No errors were detected in 24 of the 24 files tested.
Steps to reproduce
- Download a pack containing stickers with a palette on a iOS device (see example above)
Actual result: animated stickers are not animated
Expected result: animated stickers are animated
Device info
Device: iPhone 11 Pro
iOS version: 14.1
Signal version: 3.21.0.1
Note that I don't own an iOS device, so I can't provide debug log or further information.
Thanks for the detailed report, we will look into this.
The animation doesn't work if I try to add the animated PNG that is saved in the Photo Library. All I get is just a static picture. The transparent background of the picture is just white.
The PNG I tried has no palette.
pngcheck 01.png ✔
OK: 01.png (370x300, 32-bit RGB+alpha, non-interlaced, 60.4%).
Is this still relevant? If so, what is blocking it? Is there anything you can do to help move it forward?
This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
still not working
This is an example pack that doesn't work.
https://signalstickers.com/pack/8dd301e0ed9f45dfc232774ae845780e