Error converting animated gif to animated webp

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Convert monster-hunter-3-ulti51ozt.gif to an animated webp file using 
gif2webp.exe.
2. Extract frames using webpmux.exe.
3. Frames after around 100 are corrupted.

What is the expected output? What do you see instead?

Expected to see the same frames as the GIF. Resultant frames seem to have a 
value overflow.

What version of the product are you using? On what operating system?

gif2webp.exe and webpmux.exe from libwebp 0.30rc6. Running on Windows XP 
service pack 3. Used both lossless and lossy compression, both formats had this 
error.

Please provide any additional information below.

Attached original gif and frame 166 from the resultant animated webp file.

Original issue reported on code.google.com by file.xtr...@gmail.com on 21 Mar 2013 at 7:50

Attachments:

• monster-hunter-3-ulti51ozt.gif
• frame166.webp

[GoogleCodeExporter]

i had a look and here are some remarks:

* first 'faulty' frame is actually frame #91.
* the animation plays fine with 'vwebp' tool
* the 'noise' one sees on the individually decoded frames seems to be actually 
transparent pixels, that let the background color show through. That's why 
vwebp plays correctly, although individual frame look strange.

Original comment by pascal.m...@gmail.com on 21 Mar 2013 at 10:17

• Changed state: Started

[GoogleCodeExporter]

This is WAI.

Original comment by jz...@google.com on 30 Mar 2013 at 4:08

• Changed state: Invalid