Issue 309 in webp: WebP animation can't play only once

[gn00742… via monorail]

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

New issue 309 by gn00742...@gmail.com: WebP animation can't play only once
https://bugs.chromium.org/p/webp/issues/detail?id=309


1. use webpmux make a webp animation image and set loop to 1
2. webp loop twice

According to this discuss:

https://bugs.chromium.org/p/chromium/issues/detail?id=592735

chromium change webp loop behavior.

but it's will cause webp animation can't play only once.

if you don't set loop option,loop value will default to 0 which is infinite.

maybe webpmux tool should not write loop option if user not set? or chromium should revert this change?


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[schen… via monorail]

Comment #1 on issue 309 by sche...@chromium.org: WebP animation can't play only once
https://bugs.chromium.org/p/webp/issues/detail?id=309#c1

As the description says, resolution of this issue is blocking Chromium development. Users are in a situation where they cannot play a webp video only once due to incompatibilities between webp and gif interpretations of the loop value.

For discussion of the Chrome team's reasoning, please see the linked bug: crbug.com/592735.

[pkast… via monorail]

Comment #2 on issue 309 by pkas...@chromium.org: WebP animation can't play only once
https://bugs.chromium.org/p/webp/issues/detail?id=309#c2

My suggestion:

Make the loop count in WebP be the actual number of times to loop through the image (i.e. one less than GIF). This is the more sane interpretation of the "loop count" field anyway, any eliminates the "behavior hole". Doing this assumes any GIF-to-WebP transcoding tools can make this change appropriately, and restores the original WebP behavior (pre- https://codereview.chromium.org/1780463007 ).

Then, probably leave GIF and WebP permanently disagreeing. But, if you want, try to get all browsers to change their interpretation of how GIF looping should work. At least Firefox and maybe Safari (according to one report I heard) have done things for GIF this way for parts of their lifespan. Then GIF would match.

Note that I consider this last a high-cost, low-benefit action. I don't see why we need to have GIF and WebP interpret the value of this field the same way. Just make the spec clear.

[jz… via monorail]

Updates:
Owner: jz...@google.com
Status: Fixed

Comment #3 on issue 309 by jz...@google.com: WebP animation can't play only once
https://bugs.chromium.org/p/webp/issues/detail?id=309#c3

crbug.com/649264 has been resolved. Since the webp format is finalized we decided to reduce the loop count by 1 in Chrome to allow files to be able to play once.

[jz… via monorail]

Comment #4 on issue 309 by jz...@google.com: WebP animation can't play only once
https://bugs.chromium.org/p/webp/issues/detail?id=309#c4

More info is available in the public announcement:
https://groups.google.com/a/webmproject.org/d/msg/webp-discuss/rJ2a0j1BNQI/XXqK918ZEQAJ