Animated WebP image issue using LoadTexturesAsync

[dw8869]

using unity.webp 0.3.11

Due to our application scenario, asynchronous loading is required.
There is an issue of image output when you call the method below and use it.

WebP.Experiment.Animation.WebP.LoadTexturesAsync(byte[])

We tested 3 images.

• https://colinbendell.github.io/webperf/animated-gif-decode/2.webp
• https://colinbendell.github.io/webperf/animated-gif-decode/3.webp
• https://mathiasbynens.be/demo/animated-webp-supported.webp

There is a problem with the pixel looking broken as shown in the screenshot below.

And the error log below is also output.
[WebPDecoderWrapper] Bytes to texture error: LoadRawTextureData: not enough data provided (will result in overread).

[netpyoung]

I also have same problem of that. There is something what I can't understand when passing decoding option. So please avoid to use Experiment that function.

• check Samples/example2/animation.unity then moidfy WebpAnimation.cs logic to fit your game.

[dw8869]

@netpyoung
As I checked, the WebPDemuxGetFrame function returns the width and height values abnormally.

[netpyoung]

@dw8869

It seems so. WebP.Experiment.Animation.WebPDecoderWrapper.CreateDecoder couldn't create proper decoder.
I also tried to modify to change decoder's behaviour via options but failed until now.

[dw8869]

any updates?

[Razhagal]

Hello, I know this is relatively old issue without any updates to it but I have a need to optimize out use of animated webp in our projects. The current and easy approach is to use the first animated example with full frames for animation. This does a big hit on the memory when relatively large animated image is decoded into several big textures to animate, each taking width * height * 4 bytes.
One option is to not use full frames but only the fragments of each animation frame - only the changes to the frame. I dug again into the last Example3 code with async decoding and loading of webp for second time and found the issues you guys face.
The issue [WebPDecoderWrapper] Bytes to texture error: LoadRawTextureData: not enough data provided (will result in overread). is caused because different frames have different image size while the part where it creates the Texture2d's uses the full canvas size. This leads to the aforementioned error and skipping creation of frame textures. To fix this one must use the actual frame width and height when creating the Texture2d. All the required data is present in the WebPIterator used in WebPDecodeJob but it is not used outside the Texture2DExt.LoadRGBAFromWebP line. After fixing this the error goes away and the example animated image becomes more dynamic, but still broken.
This leads to the other issue. The way the current example treats the animated webp is entirely wrong. Using the WebPIterator to extract each frame fragment gets you only the changed part of the frame, not the whole frame. And different frame fragments can have different size and x/y offsets from the top-left corner of the whole canvas. Those are supposed to sort of overlay one another in some sort of animation, not just loop over each texture with a single RawImage object.
In my testing I simply stacked each frame one on top of another, each object with the actual size of the frame fragment and offset on required x/y (data you get from the Iterator) and it looked perfect. I haven't reached the step to actually animate them yet because I'm gonna be implementing using the WebPIterator in my own project according to my needs and structure but those 2 main issues seem to cause the confusion and error.
Hope this helps!

[zpLin]

I followed Razhagal method to create this.
https://github.com/zpLin/unity.webp/blob/master/unity_project/Assets/unity.webp/Runtime/Texture2DAnimationEx.cs