calibre and .webp

[carmenchu]

Looking into a plug-in internals, I just found
IMAGE_FILES = ['.png','.jpg','.jpeg', '.gif', '.bmp', '.svg']
NO '.webp'.
Moreover, trying to update a book cover in calibre with a .webp file, it got silently converted to .jpg
Now, I have collated an epub in sigil (a guide for some Gimp plug-ins) from html pages, and both the cover and a part of the illustrations--particularly, all the animations--are .webp: it works flawlessly in both calibre e-viewer and Book Browser.
To get Sigil to deal properly with the images, I was asked to supply the MIME type, which per wikipedia is image/webp.
I dare say not all devices will accept the format--but that shouldn't put a restriction on everybody...
And, yes: it is not included in the epub 2 specification... and so isn't much CSS3, even when it works for many of us.

[kovidgoyal]

calibre covers are always going to be in a single format and that format is JPEG. trying to change that is waaaaaay to likely to break things. As for webp feel free to use it in other parts of your book if you like, calibre doesnt care, though it is quite likely your book will not work in most reading software.

[carmenchu]

Originally Posted by kovidgoyal

calibre covers are always going to be in a single format and that format is JPEG. trying to change that is waaaaaay to likely to break things.

Sorry: so, when I want a cover with transparency, I just add it in sigil...

Originally Posted by kovidgoyal

As for webp feel free to use it in other parts of your book if you like, calibre doesnt care, though it is quite likely your book will not work in most reading software.

Well, the only reader I care for is calibre e-viewer, so's mutual...
Anyway, plug-ins ought to respect existing .webp images, unless they mean to do a conversion to pander to user-agent quirks...

[Quoth]

I don't know ANY ebook reader that supports animations. So is the "ebook" just for onscreen on Mac, Windows and Linux? Or do some popular iOS and Android ereader apps support animation?

Calibre conversions work well at making sure an ebook works on the ereaders that use the format.

[carmenchu]

Originally Posted by Quoth

I don't know ANY ebook reader that supports animations. So is the "ebook" just for onscreen on Mac, Windows and Linux? Or do some popular iOS and Android ereader apps support animation?

Calibre conversions work well at making sure an ebook works on the ereaders that use the format.

1. I read at my desktop: so, calibre e-viewer--animations (.gif or .webp) OK
2. When I shared my guide to Gimp plug-ins in a Gimp forum, I tested in Book Browser (found in another mobilered forum, reads epubs in computers: try here) and everything equally fine. I conclude (without testing!) that all browser-based epub readers--which ought to work in anythink which supports a browser (computer, tablet, smartphone...) should be able to show those animations, at the very least. Those can be included as any other images in the epub (<img .../> tag): some other formats may require <object... /> or something else.

[DNSB]

I wouldn't recommend using webp images. They are not supported in the epub2 or epub3 specification. The four supported image formats are gif, jpeg, png and svg/xml. Using other formats can and does cause issues on quite a few ereaders and will get your ebook bounced from Amazon, Smashwords, etc. One author I did some work for insisted on using webp images and got rejected on multiple sites for that reason.

For a personal use only document, knock yourself out. But please don't waste other people's time by complaining that a program is attempting to follow the standard to allow generating an ebook that will work on the majority of devices, however much you feel that your preferred image format should be supported.

[carmenchu]

Originally Posted by DNSB

But please don't waste other people's time by complaining that a program is attempting to follow the standard to allow generating an ebook that will work on the majority of devices, however much you feel that your preferred image format should be supported.

I have no 'favorite format': simply, editing my own cover, maps and illustrations, I have found, as many others, that each format is better for some kind of images. And technical works are even more exacting and clamour strongly for some unusual and little know formats...

Originally Posted by DNSB

...Using other formats can and does cause issues on quite a few ereaders and will get your ebook bounced from Amazon, Smashwords, etc. One author I did some work for insisted on using webp images and got rejected on multiple sites for that reason...

I would add 'now'--not so long ago I was hearing the same about svg, wasn't I?

Personally, instead of trying to limit everybody to the intersection of what 'the most usual' would support, I would aim at using the better available and expect the 'the most usual' to update... they would, someday...?
Anyway, as lifelong reader, I would rather not voice my very personal opinion of editors and their policies--which I should thank instead for forcing me to learn english.

[DNSB]

Originally Posted by carmenchu

I would add 'now'--not so long ago I was hearing the same about svg, wasn't I?

Personally, instead of trying to limit everybody to the intersection of what 'the most usual' would support, I would aim at using the better available and expect the 'the most usual' to update... they would, someday...?
Anyway, as lifelong reader, I would rather not voice my very personal opinion of editors and their policies--which I should thank instead for forcing me to learn english.

Nothing to do with an editor. You try running an epub with webp images through epubcheck and you get error messages. That is enough to have your submission bounced back to you. You can try to explain to an automated process that your webp image is great and it doesn't matter that properties="cover-image" is not defined for a webp or that an image/webp media-type calls for a manifest fallback. Those were the two of the error messages I remember from submitting an epub with webp images.

And yes, automated pre-processing is rather popular since it saves humans from wasting their time on the "garbage in" files. Much like when interns got to read through the slush pile looking for the needle in the dung heap.

[carmenchu]

Do you mean the complaint
'Non-standard image resource of type image/webp found'?
I get as meaningful complaints about this line:
<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">,
appearing in lots of epubs from lots of sources... left bothering about it: as a reader, it means nothing. Far worse:
- typos galore (but for hut and the like)
- semantics absent (that may be the author: but editors ought to do something, especially when promoting a 'new author'...)
- unfriendly formating
- nonsensical translations...
Anyway, mine is sctrictly a personal viewpoint: I love the books in the my library and I love to give them the best layout I can contrive. No 'use and discard' for me.

[Quoth]

Originally Posted by carmenchu

I conclude (without testing!) that all browser-based epub readers--which ought to work in anythink which supports a browser (computer, tablet, smartphone...) should be able to show those animations, at the very least.

But like PDFs in a browser, ePubs in a browser is purely a convenience, though admittedly not as daft. Most browsers don't support epub at all, MS did for a while on Edge, purely for THEIR convenience.
If you want people to use a browser, then use HTML not epub.

[DNSB]

Originally Posted by carmenchu

Do you mean the complaint
'Non-standard image resource of type image/webp found'?
I get as meaningful complaints about this line:
<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">,
appearing in lots of epubs from lots of sources... left bothering about it: as a reader, it means nothing. Far worse:
- typos galore (but for hut and the like)
- semantics absent (that may be the author: but editors ought to do something, especially when promoting a 'new author'...)
- unfriendly formating
- nonsensical translations...
Anyway, mine is sctrictly a personal viewpoint: I love the books in the my library and I love to give them the best layout I can contrive. No 'use and discard' for me.

The error for the <html> tag is fairly common. And relatively harmless though adding lang="xx" to the <html> tag is not supported in epub2. One of my saved searches cleans that up. It won't keep your ebook from displaying on any platform that I am aware of.

Typos? Semantics? Homonyms? Formatting? The epub specifications don't care about what you do with your text. It's your ebook. Screw up the content to your heart's content. Hmmm... that's pretty much what ScrambleEbook and Borkify do.

Ebooks in my library? They get the formatting I prefer. Save a few bytes so I can't read them on my devices? No futtering way.

Ebooks I work on for other people? They will pass epubcheck. They will have formatting that looks good across multiple devices and reading platforms. On request, I may even do a quick read and correct any egregious errors.

You might also want to look at Usage statistics of WebP for websites. Other sites have similar statistics with the highest claiming 0.4% of websites using webp images on their survey of the "top" 500 sites. If you drop Google, the number went to 0.2%.