Sharp removes GIF animation

[Spedwards]

Possible bug

When passing a path to an animated GIF and using either toFile(..) or toBuffer(), the returned GIF has no animation. The toBuffer() method is important to me as I need it to upload images to an image host.

Is this a possible bug in a feature of sharp, unrelated to installation?

• Running npm install sharp completes without error.
• Running node -e "require('sharp')" completes without error.

If you cannot confirm both of these, please open an installation issue instead.

Are you using the latest version of sharp?

• I am using the latest version of sharp as reported by npm view sharp dist-tags.latest.

If you cannot confirm this, please upgrade to the latest version and try again before opening an issue.

If you are using another package which depends on a version of sharp that is not the latest, please open an issue against that package instead.

What is the output of running npx envinfo --binaries --system --npmPackages=sharp --npmGlobalPackages=sharp?

  System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz
    Memory: 9.15 GB / 31.92 GB
  Binaries:
    Node: 16.15.0 - ~\.nvm\versions\node\v16.15.0\bin\node.EXE
    Yarn: 1.22.4 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 8.5.5 - ~\.nvm\versions\node\v16.15.0\bin\npm.CMD
  npmPackages:
    sharp: ^0.32.0 => 0.32.0

What are the steps to reproduce?

await sharp(pathToAnimatedGif).gif().toFile('sample.gif')

The file, sample.gif, will not be animated. This also applies to the toBuffer() method but I'm unsure how best to showcase that.

What is the expected behaviour?

The returned image/buffer should include the animation data. According to the AnimationOptions interface, loop should default to 0 (infinite). I'm unsure if that's even the issue as 1 would at least show the other frames. All I'm getting is a static image.

Please provide a minimal, standalone code sample, without other dependencies, that demonstrates this problem

const sharp = require('sharp')

const pathToAnimatedGif = 'some_animated_gif.gif'
sharp(pathToAnimatedGif).gif().toFile('sample.gif')

Please provide sample image(s) that help explain this problem

some_animated_gif.zip or imgur link

[Spedwards]

Hmm... I ended up doing some exploring after posting this to see if I could find another library to handles GIFs in the meantime, but something referenced sharp and included a second argument to the sharp constructor, { animated: true }. That resolved the animation issue however it appears to more than double the file size of that example image I've included. Is there anyway around that?

[lovell]

It looks like the some_animated_gif.gif file has been highly optimised via a tool such as gifsicle, including some clever use of different transparent palette indexes per frame:

gifsicle --info some_animated_gif.gif 
* some_animated_gif.gif 36 images
  logical screen 700x700
  global color table [256]
  background 0
  loop forever
  + image #0 700x700
    disposal asis delay 0.04s
  + image #1 700x693 at 0,7 transparent 153
    disposal asis delay 0.04s
  + image #2 700x693 at 0,7 transparent 150
    disposal asis delay 0.04s
  + image #3 700x625 at 0,75 transparent 151
    disposal asis delay 0.04s
  + image #4 686x585 at 14,115 transparent 146
    disposal asis delay 0.04s
...

Please see #3610 for a previous related question and a possible suggestion to create a wrapper that brute forces its way through various configuration options to find the smallest output, as this is what GIF optimisation tools do.

[lovell]

I hope this information helped. Please feel free to re-open with more details if further assistance is required.