Does Pale Moon support AVIF?

[marigold]

Recently came across this site - https://arthur.pizza/2025/12/animated-a ... odern-web/ - that talks about AVIF. Pale Moon however doesn't display the animated AVIF media in it (AV1 is enabled in PM). The site works fine on Firefox though. Doesn't Pale Moon support AVIF? (If no, I think it should). The argument for this - I am quite aware of the competing JPEG-XL format, which, like many of you, I do consider to be technically superior to other current offerings in this field. My argument for AVIF is simply from the users perspective - they particularly don't want to care about any "codec wars" and just want their browser to display a site properly. If Pale Moon doesn't support some media format and breaks any website with such media content, the lay user is likely to just assume that Pale Moon is "broken". Especially when other browsers display the site "properly". Also, while many of us may not like the way Google is pushing these formats, let's not forget that while these codecs may be inferior, they are still open source, patent-free codecs, and it is still in all our better interest that they become popular (and hopefully improve).

[RealityRipple]

Please use the search feature before making duplicate topics, particularly for things that have already been heavily discussed.

[Moonchild]

Despite this already being discussed before on the forum, providing an answer here anyway to address the particular issues with this question.

Doesn't Pale Moon support AVIF?

No, it does not. See other threads.

My argument for AVIF is simply from the users perspective - they particularly don't want to care about any "codec wars" and just want their browser to display a site properly.

Then they should use a ubiquitous image format (JPG, PNG, etc.) or leverage one of the many browser-agnostic methods to fall back to a ubiquitous format if AVIF isn't supported, e.g. content negotiation using the standard http Accept: header.

they are still open source, patent-free codecs

No, AV1 is royalty-free, at least for now, but not patent-free! It is patented and falls under a licensing scheme, which has even been contested in the EU as harming innovation. See https://en.wikipedia.org/wiki/AV1#Patent_claims

[marigold]

Thank you for your patience in kindly explaining the facts.

Then they should use a ubiquitous image format (JPG, PNG, etc.) or leverage one of the many browser-agnostic methods ...

By user, I meant the end average user browsing a site, not the web developer. Sadly, due to historic reasons we know that browser engine developers decided to be "kinder" to poorly coded HTML to make it easier for websites to be created and thus XHTML and strict parsing is not the norm. All that has just made current web developers more lazy and careless, in my opinion. Most of them today don't even bother testing their sites with any browser other than Chrome. My concern was just to make Pale Moon browser more user-friendly - to grow Pale Moon's user base, we need to be accommodating to the needs of the lay browser user who often are not advanced users like us. While AVIF with AV1 may have be an inferior product, Pale Moon should consider supporting it because it is open source and its patents are royalty-free (not, as I mistakenly assumed patent-free). If you cannot for some other reasons (like legal ones), I suggest at least displaying an in-place user-friendly message to the user informing them that AVIF is currently not supported; e.g.:

AVIF media not loaded - Pale Moon currently doesn't support rendering AVIF content for <explanation>

(Ofcourse, this doesn't mean we need to sacrifice the core values behind Pale Moon - like the reason for not including DRM in it. Instead, we need Pale Moon fail "gracefully" - in a user-friendly manner - when a Pale Moon user encounters a website with DRM or AVIF, while educating the user about the failure to load some content).

[Gemmaugr]

we need to be accommodating to the needs of the lay browser user who often are not advanced users like us.

The normal user sadly has no idea (or don't care) what's happening in the background for these kinds of API's and features, and would lead to the google monoculture having been able to implement FLoC, Topics, WEI, and now PerformanceObserver. That would mean a total absence of privacy, even more bloat, and a walled garden internet. Again, something most browser end users don't really mind..

AVIF media not loaded - Pale Moon currently doesn't support rendering AVIF content for <explanation>

(Ofcourse, this doesn't mean we need to sacrifice the core values behind Pale Moon - like the reason for not including DRM in it. Instead, we need Pale Moon fail "gracefully" - in a user-friendly manner - when a Pale Moon user encounters a website with DRM or AVIF, while educating the user about the failure to load some content).

This would be good though. Also notifying the site developers at the same time (if CSP reports aren't already doing that?).

[Moonchild]

we need Pale Moon fail "gracefully" - in a user-friendly manner - when a Pale Moon user encounters a website with DRM or AVIF, while educating the user about the failure to load some content).

So what are you expecting? That the browser informs the user instead of supporting the format with an infobar or something? That is unfortunately just not feasible - it will combat with fallbacks because it means we can't treat it as a failure on the web side; if we do it would lead to a website that does do it properly falling back to a supported format but the browser still throwing up a message which is what we don't want either. There is no way to "fail gracefully" here. We either support it or we don't. If we don't, then we either thrown an error and prevent fallbacks, or we let the website handle it (which will either succeed or fail, depending on what the webmaster does.

My remark was indeed what webmasters should do, not anything the user can or should do.

[Stargate38]

Could you please add AVIF support to PM? I don't care how bad/inefficient the format is, I just want to see support for it, preferably before v35.0.0. I see no valid reason why it could never be added, unlike DRM. There are some websites that use that image format without fallback (i.e. Quanta Magazine), and I don't want to have to use alternate browsers just to view those websites. Maybe port it over from FF, if possible.

[back2themoon]

My non-requested advice to users facing this problem: you should immediately contact these websites first. Tell them they should provide fallback because AVIF is NOT a global/ubiquitous standard where image formats are concerned, and not everyone is using Chrome and the like.

I had this problem with a single website, I contacted them and they did solve it.

As for Pale Moon native AVIF support then sure, it'd be nice to have, but I suspect there are far more pressing Web Compatibility issues than this.

I just want to see support for it, preferably before v35.0.0... ... Maybe port it over from FF, if possible.

You are assuming that it's a fairly simple "copy/paste from Firefox" affair. I can only assume it is not.

[Basilisk-Dev]

How often are websites actually using the AVIF format? Is that becoming more common?

[vannilla]

How often are websites actually using the AVIF format? Is that becoming more common?

For what it's worth I found AVIF in very few places, most of them being news websites and only one or two being "user-run" (for a lack of a better word). The news sites were "large" ones, the more local news used other long-standing formats.
It's only anecdotal evidence and it doesn't reflect anything but my own experience, but from that personal experience my point of view is that AVIF is barely in use and in places where swapping the file with something else is oftentimes trivial and all it takes is a polite e-mail or two.

[dinosaur]

How often are websites actually using the AVIF format? Is that becoming more common?

Yes, it is... Just had one of my usual sites switching to it for image previews.

It would be nice to get AVIF support in PM.

[athenian200]

I think the issue with adding it is that it would mix image processing and video processing code in a way we're not all that comfortable with. I think other formats let us separate those concerns in a way AVIF wouldn't, or at least that's my thinking.

So does this mean the worst possible format is winning? I really hope the web does not standardize on AVIF...

[back2themoon]

So does this mean the worst possible format is winning? I really hope the web does not standardize on AVIF...

I am afraid the trend is growing. Nowhere near standardized yet of course, but there's a good chance this will happen.

Or at least a Web Compatibility issue, widespread enough to significantly affect us.

[BenFenner]

Forgive my potential ignorance, but why wouldn't places for the most part move toward JPEG XL instead?
If I were moving my web site to a new image format, it would be that (lossless JXL in some cases, lossy in others).

(Especially now that Chrome and others mercifully reversed course on that.)

[athenian200]

Forgive my potential ignorance, but why wouldn't places for the most part move toward JPEG XL instead?
If I were moving my web site to a new image format, it would be that (lossless JXL in some cases, lossy in others).

(Especially now that Chrome and others mercifully reversed course on that.)

Only reason I can think of is, ironically, ignorance of alternatives. The web devs probably heard someone talking about AVIF, maybe upgraded their old GIFs to that format because it was advertised that way, and patted themselves on the back for being "modern." Or they wanted to convert a video into a moving image and thought it was easier.

Though hypothetically... if I did want to support AVIF, I'd likely want to support it as a video file rather than an image file if I detect its use. Like I would just refuse to go through the image pipeline and treat it as a video file, maybe even displaying player controls, as a way of mocking the web dev for choosing it and letting everyone know they used a video file as an image thinking it was a real image format. Only problem of course is that we're expected to accept it through an img tag, which turns the gears in motion to send it down entirely the wrong pipeline. If it were anything else, we could do it.

[back2themoon]

Here's a rather sad example. Not the norm as mentioned, but still.

https://www.rosa.gr/

[athenian200]

Here's a rather sad example. Not the norm as mentioned, but still.

https://www.rosa.gr/

That website actually displays a 403 Forbidden error for me in Pale Moon. Like, I can't even see it... works fine in Edge, though.

I can tell it's definitely an unfriendly website.

[back2themoon]

Off-topic:

That website actually displays a 403 Forbidden error for me in Pale Moon.

That's strange. Actually, I recently had a local website giving me that 403 Forbidden error on Pale Moon alone. But it was not this one (the 403 issue was solved with an email exchange).

[back2themoon]

Here what these guys are now doing: https://www.tanea.gr/ and https://www.in.gr/
I will contact them but AVIF issues keep cropping up.

The image URLs look like normal .jpg but Pale Moon prompts to open the file instead. Since PM does not support AVIF, this seems to be caused by the site/CDN serving AVIF data from .jpg URLs. (wtf)

If a harmless query string is added to the same image URL, for example `?x=1`, the image loads normally. So the site probably bypasses its optimized AVIF cache and sends a normal JPEG fallback.

Looks like bad image-format negotiation by the website/CDN: AVIF should only be sent to browsers that actually support it. Got an AI fix with this userscript:

Code: Select all

// ==UserScript==
// @name        Alter Ego AVIF image fallback for Pale Moon
// @namespace   local
// @version     0.4.0
// @description Adds a harmless query parameter to failed Alter Ego WordPress images so Pale Moon receives JPEG/PNG instead of AVIF disguised as JPG/PNG.
// @match       https://www.tanea.gr/*
// @match       https://www.in.gr/*
// @run-at      document-start
// @grant       none
// ==/UserScript==

(function () {
    'use strict';

    var PARAM = 'pm-avif-fallback=1';

    var IMAGE_URL_RE =
        /^https:\/\/(?:[^\/]+\.)?(?:in\.gr|tanea\.gr|tovima\.gr|vita\.gr)\/wp-content\/uploads\/.+\.(?:jpe?g|png)(?:$|[?#])/i;

    var SRCSET_URL_RE =
        /(https:\/\/(?:[^\/]+\.)?(?:in\.gr|tanea\.gr|tovima\.gr|vita\.gr)\/wp-content\/uploads\/[^\s,]+\.(?:jpe?g|png))(\s+\d+[wx])?/gi;

    function addFallbackParam(url) {
        if (!url || url.indexOf(PARAM) !== -1 || !IMAGE_URL_RE.test(url)) {
            return url;
        }

        return url + (url.indexOf('?') === -1 ? '?' : '&') + PARAM;
    }

    function fixSrcset(srcset) {
        if (!srcset || srcset.indexOf(PARAM) !== -1) {
            return srcset;
        }

        return srcset.replace(SRCSET_URL_RE, function (match, url, descriptor) {
            return addFallbackParam(url) + (descriptor || '');
        });
    }

    function fixElement(el) {
        if (!el || el.getAttribute('data-pm-avif-fallback-done') === '1') {
            return false;
        }

        var changed = false;

        var oldSrc = el.getAttribute('src');
        var newSrc = addFallbackParam(oldSrc);

        if (oldSrc && newSrc !== oldSrc) {
            el.setAttribute('src', newSrc);
            changed = true;
        }

        var oldSrcset = el.getAttribute('srcset');
        var newSrcset = fixSrcset(oldSrcset);

        if (oldSrcset && newSrcset !== oldSrcset) {
            el.setAttribute('srcset', newSrcset);
            changed = true;
        }

        if (changed) {
            el.setAttribute('data-pm-avif-fallback-done', '1');
        }

        return changed;
    }

    function fixPictureSources(img) {
        var parent = img && img.parentNode;

        if (!parent || !parent.tagName || parent.tagName.toLowerCase() !== 'picture') {
            return;
        }

        Array.prototype.forEach.call(parent.querySelectorAll('source[srcset]'), fixElement);
    }

    document.addEventListener('error', function (event) {
        var target = event.target;

        if (!target || !target.tagName || target.tagName.toLowerCase() !== 'img') {
            return;
        }

        fixPictureSources(target);
        fixElement(target);
    }, true);
})();

[dinosaur]

Your fix won't work for sites purposely using AVIF for images and video previews.

The only viable solution is to implement AVIF support in PM.