Issue 517 in webp: Exporting to animated WebP doesn't preserve the channels

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marti… via monorail

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Apr 15, 2021, 12:23:59 PMApr 15
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Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 517 by marti...@gmail.com: Exporting to animated WebP doesn't preserve the channels
https://bugs.chromium.org/p/webp/issues/detail?id=517

What steps will reproduce the problem?
I'm doing third party API ingegration. Running the example from the documentation page.
```
WebPAnimEncoder* enc = WebPAnimEncoderNew(width, height, &enc_options);
while(<there are more frames>) {
WebPConfig config;
WebPConfigInit(&config);
WebPAnimEncoderAdd(enc, frame, timestamp_ms, &config);
}
WebPAnimEncoderAdd(enc, NULL, timestamp_ms, NULL);
WebPAnimEncoderAssemble(enc, webp_data);
WebPAnimEncoderDelete(enc);

```

What is the expected output? What do you see instead?
Issue is related to exporting animated image with a wrong number of channels.
When I export animated webp image from 5 images, whose numbers of channels are equal to 3, animated webp image contains 5 images with channels {3, 4,4,4,4}(Means it preserves right number of channels only for the first frame)


What version of the product are you using? On what operating system?
I'm on Linux Ubuntu 20.04
I'm using the current webp master.

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jz… via monorail

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Apr 23, 2021, 4:23:32 PMApr 23
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Comment #1 on issue 517 by jz...@google.com: Exporting to animated WebP doesn't preserve the channels
https://bugs.chromium.org/p/webp/issues/detail?id=517#c1

Thanks for the report.

How are you determining the number of channels in the animated webp? Does the image render incorrectly?

How did you import the data into the WebPPicture (frame)? If there was non-trivial alpha data then that may explain the difference, though it sounds like your source is expected to have three channels only. If you have some sample frames or a more complete code snippet it may help diagnose the issue.

jz… via monorail

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Jul 3, 2021, 2:15:06 PMJul 3
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Updates:
Labels: Needs-Feedback

Comment #2 on issue 517 by jz...@google.com: Exporting to animated WebP doesn't preserve the channels
https://bugs.chromium.org/p/webp/issues/detail?id=517#c2

Any update on this one? Are you able to provide the source images, a sample encode and the code used to produce it so we can take a look?
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