Add @mediabunny/ac3 extension package

docs/guide/extensions/ac3.md

@@ -0,0 +1,33 @@
+# @mediabunny/ac3
+
+Browsers have no support for AC-3 (Dolby Digital) or E-AC-3 (Dolby Digital Plus) in their WebCodecs implementations. This extension package provides both a decoder and encoder for use with Mediabunny, allowing you to decode and encode these codecs directly in the browser. It is implemented using Mediabunny's [custom coder API](../supported-formats-and-codecs#custom-coders) and uses a fast, size-optimized WASM build of [FFmpeg](https://ffmpeg.org/)'s AC-3 and E-AC-3 coders under the hood.
+
+<a class="!no-underline inline-flex items-center gap-1.5" :no-icon="true" href="https://github.com/Vanilagy/mediabunny/blob/main/packages/ac3/README.md">
+	GitHub page
+	<span class="vpi-arrow-right" />
+</a>
+
+## Installation
+
+This library peer-depends on Mediabunny. Install both using npm:
+```bash
+npm install mediabunny @mediabunny/ac3
+```
+
+Alternatively, directly include them using a script tag:
+```html
+<script src="mediabunny.js"></script>
+<script src="mediabunny-ac3.js"></script>
+```
+
+This will expose the global objects `Mediabunny` and `MediabunnyAc3`. Use `mediabunny-ac3.d.ts` to provide types for these globals. You can download the built distribution files from the [releases page](https://github.com/Vanilagy/mediabunny/releases).
+
+## Usage
+
+```ts
+import { registerAc3Decoder, registerAc3Encoder } from '@mediabunny/ac3';
+
+registerAc3Decoder();
+registerAc3Encoder();
+```
+That's it - Mediabunny now uses the registered AC-3/E-AC-3 decoder and encoder automatically.

docs/guide/supported-formats-and-codecs.md

@@ -59,7 +59,7 @@ Mediabunny ships with built-in decoders and encoders for all audio PCM codecs, m
 - `'ulaw'` - μ-law PCM
 - `'alaw'` - A-law PCM
 
-[^1]: AC-3 and E-AC-3 are not natively supported by WebCodecs. To encode or decode these codecs, you must provide a [custom coder](#custom-coders).
+[^1]: AC-3 and E-AC-3 are not natively supported by WebCodecs. To encode or decode these codecs, you can use the [`@mediabunny/ac3`](./extensions/ac3) extension package, or provide your own [custom coder](#custom-coders).
 
 ### Subtitle codecs