Issue 245 in webp: gif2webp -lossy produces corrupted Webp for GIFs with transparency

[we...@googlecode.com]

Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 245 by KTa...@gmail.com: gif2webp -lossy produces corrupted Webp
for GIFs with transparency
https://code.google.com/p/webp/issues/detail?id=245

What steps will reproduce the problem?
1. Run gif2webp -lossy on the attached GIF

What is the expected output? What do you see instead?
Expected: Webp that looks like the original GIF
Actual: Webp that has weird transparency, looks corrupted, does not reflect
the original GIF

What version of the product are you using? On what operating system?
libpwebp 0.4.3 on linux server

Please provide any additional information below.
This doesn't repro if I don't specify lossy


Attachments:
emu.gif 359 KB
emu-lossy.webp 195 KB

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[we...@googlecode.com]

Updates:
Status: Accepted
Owner: urv...@google.com

Comment #1 on issue 245 by urv...@google.com: gif2webp -lossy produces

corrupted Webp for GIFs with transparency
https://code.google.com/p/webp/issues/detail?id=245

Thanks for the report!
I can reproduce this offline.

The output WebP is correct when using v0.4.2, but shows these artifacts in
v0.4.3
Likely culprit is:
https://gerrit.chromium.org/gerrit/gitweb?p=webm/libwebp.git;a=commit;h=5691bdd9da9239d9dbd680bd16af98c6123b2c02

At the same time, the output is correct at HEAD in master branch:
https://gerrit.chromium.org/gerrit/gitweb?p=webm/libwebp.git
This is probably because the HEAD revision uses the new and re-written
AnimEncoder API in place of gif2webp_util.[ch].

Digging deeper in gif2webp_util to figure out the problem.

[we...@googlecode.com]

Comment #2 on issue 245 by urv...@google.com: gif2webp -lossy produces

corrupted Webp for GIFs with transparency
https://code.google.com/p/webp/issues/detail?id=245

Looks like the fix for this is in master branch:
https://gerrit.chromium.org/gerrit/#/c/72086/, but not in the v0.4.3 branch.

I'll work on getting that fix into v0.4.x as well.

[we...@googlecode.com]

Comment #3 on issue 245 by KTa...@gmail.com: gif2webp -lossy produces

corrupted Webp for GIFs with transparency
https://code.google.com/p/webp/issues/detail?id=245

Thanks for looking into this! Is there an estimated date for the next
release?

[we...@googlecode.com]

Comment #4 on issue 245 by urv...@google.com: gif2webp -lossy produces

corrupted Webp for GIFs with transparency
https://code.google.com/p/webp/issues/detail?id=245

To avoid issues like this in the future, we'll do some more verification
before the release. So, a very rough estimate for the release would be a
couple of weeks.