Ping-pong looping?

[vapo...@gmail.com‏]

Is it possible to create a webp animation that ping-pongs instead of looping normally? 

It would play forwards once, then backwards once and repeat

I've needed this for several of the animations I created, and ended up adding a second copy of the frames in reverse order, doubling the file size

[James Zern‏]

Hi,

On Thursday, October 13, 2016 at 11:59:14 AM UTC-7, vapo...@gmail.com wrote:

Is it possible to create a webp animation that ping-pongs instead of looping normally? 

It would play forwards once, then backwards once and repeat

Sorry, no that's not possible.

[Jon Sneyers‏]

Maybe not very relevant for this mailing list, but FLIF does support this, in a way. It has duplicate frame detection, and compresses duplicate frames away. So you only pay for the unique frames - you can repeat them in any order however often, and it will not make the file get more than a few bytes larger.

Best,
-Jon.

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[Pascal Massimino‏]

Hi,

On Fri, Oct 14, 2016 at 7:21 AM, Jon Sneyers <jon.s...@gmail.com> wrote:

Maybe not very relevant for this mailing list, but FLIF does support this, in a way. It has duplicate frame detection, and compresses duplicate frames away. So you only pay for the unique frames - you can repeat them in any order however often, and it will not make the file get more than a few bytes larger.

Best,
-Jon.

On Oct 13, 2016 20:59, <vapo...@gmail.com> wrote:

Is it possible to create a webp animation that ping-pongs instead of looping normally? 

It would play forwards once, then backwards once and repeat

I've needed this for several of the animations I created, and ended up adding a second copy of the frames in reverse order, doubling the file size

As James said, this is no possible.

Let me add some color to this (lack of) feature:

  supporting ping-pong mode efficiently would mean storing the decoder frames as you go, in order to be able to recall them in reverse order. This what animated-webp is trying to avoid by all mean: storing past frames. At all time you only need 1 buffer for the animation decoder, no more. This might reduce the possible feature and efficiencty, but It has a large positive impact on memory use.

hope it helps,

skal/