Add webp and avif conversion to strapi-plugin-upload

rfcs/xxxx-template.md

@@ -0,0 +1,76 @@
+- Start Date: 2022-08-16
+- RFC PR: (leave this empty)
+
+# Summary
+
+Add the option to convert all uploaded images to WebP or AVIF instead of just resizing them.  This would be done via a **opt-in** parameter in `./config/plugins.js`. 
+
+# Motivation
+
+WebP and AVIF are superior formats for the web and support is growing very fast.
+
+It got to a point where some projects could decide to **only** work with these formats to improuve the user experience without adding engeneering complexity or hosting costs.
+
+One could even argue that this could make your service more ecologically friendly, by reducing the data transfered on every page load.
+
+### How much better?
+
+"WebP typically achieves an average of 30% more compression than JPEG" -- [Google WebP FAQ](https://developers.google.com/speed/webp/faq#:~:text=WebP%20typically%20achieves%20an%20average,help%20make%20the%20web%20faster.)
+
+- [Comparative study of WebP, JPEG and JPEG 2000, September 2010 - by Google](https://developers.google.com/speed/webp/docs/c_study)
+- [WebP Compression Study - by Google](https://developers.google.com/speed/webp/docs/webp_studyhttps://developers.google.com/speed/webp/docs/webp_studyhttps://developers.google.com/speed/webp/docs/webp_study)
+- [WebP vs AVIF - by avif.org](https://avif.io/blog/comparisons/avif-vs-webp/)
+
+### How good is browser support?
+
+As of Agust 2022 of the major browsers that don't support it are:
+- WebP: Only IE does not support it
+- AVIF: Edge and other smaller browsers don't have support, and Safari desktop has partial support
+
+Sources:
+- [https://caniuse.com/webp](https://caniuse.com/webp)
+- [https://caniuse.com/avif](https://caniuse.com/avif)
+
+# Detailed design
+
+This could be done directly in [/packages/core/upload/server/services/image-manipulation.js](https://github.com/strapi/strapi/blob/master/packages/core/upload/server/services/image-manipulation.js) file.
+
+A member of the community already had a prototype (no affiliation):
+https://github.com/devgar/strapi/blob/243d914efeebfdb44b236af76689c30b73fed646/packages/strapi-plugin-upload/services/image-manipulation.js
+
+Basically it would instruct `sharp` package to transform to `webp` or `avif`. This would **not** require an aditional dependency, not even a new import in the file.
+
+It will of course still resizes images like before (e.g. `large`, `medium` ...).
+
+These changes being applied only at the upload phase, would not require all the images to be reformatted making it pretty safe for retro-compatibility. And it can be turned on and off without much consequences.
+
+# Example
+
+Something like this:
+```ts
+// path: ./config/plugins.ts
+
+export default ({ env }) => ({
+  upload: {
+    config: {
+        convertAllImagesTo: 'webp' | 'avif'; // To be defined
+    },
+  },
+});
+```
+
+# Tradeoffs
+
+- Even if I'm pretty confident that is a good decision for many of us, it is **opinionated**. This could be mitigated by adding more formats as targets like `png` or `jpeg`.
+- I don't know how computer intensive it is to do the transformation.
+
+# Alternatives
+
+I guess this could be done in a plugin. But this would require replacing the official `strapi-plugin-update` for a community one. This plugin is quite big and important, I wouldn't recommend replacing it with a community-maintained plugin.
+
+If is not in the official one, I wouldn't bother doing it.
+
+# Unresolved questions
+
+- Should it support many different formats (e.g. `png` and `jpeg`) or just work with `webp` and `avif` which are the ones that should be used? More formats would make it less opinionated but would add more maintenance, and may not be that relevant.
+- How should the `./config/plugins.ts` look like?