feat!: drop VP8/VP9 output codec support

AGENTS.md

@@ -2,13 +2,13 @@
 
 ## Project Overview
 
-`@plutotcool/fsv` is a TypeScript library that defines and implements the **FSV (Fast Scrubbing Video)** format — a custom binary video format optimized for frame-accurate scrubbing on the web, with optional alpha-channel support.
+`@plutotcool/fsv` is a TypeScript library that defines and implements the **FSV (Fast Scrubbing Video)** format — a video container format optimized for frame-accurate scrubbing on the web, using H.264 and H.265 codecs with optional alpha-channel support.
 
 The library ships two distinct APIs:
 
 | API | Environment | Purpose |
 |-----|-------------|---------|
-| **Conversion** | Node.js | Converts any video file to `.fsv` using ffmpeg (`node-av`) for encoding and config extraction |
+| **Conversion** | Node.js | Converts any video file to `.fsv` (H.264/H.265 container) using ffmpeg (`node-av`) for encoding and config extraction |
 | **Decoding / Rendering** | Browser | Loads, demuxes, decodes, and WebGL2-renders `.fsv` files using native browser WebCodecs and WebGL2 APIs |
 
 The package is published to the GitHub Packages registry (`https://npm.pkg.github.com`) under the `@plutotcool` scope.
@@ -185,8 +185,8 @@ The manifest is serialized as a compact flat number array: each frame is 4 conse
 - Uses `node-av` (ffmpeg bindings) for decoding and encoding
 - Uses a `FilterComplexAPI` for pixel format conversion to `yuv420p`
 - For alpha videos, uses ffmpeg's `alphaextract` filter to produce separate color + alpha streams
-- Supported output codecs: `libx264`, `libx265`, `libvpx-vp8`, `libvpx-vp9`
-- Default output codec: `libx264` → mp4 container
+- Supported output codecs: `libx264` (H.264), `libx265` (H.265)
+- Default output codec: `libx264`
 - Default encoder settings: `crf=20`, `gopSize=5`, `maxBFrames=0`, `threadType=FF_THREAD_FRAME`
 - Sets `AV_CODEC_FLAG_GLOBAL_HEADER` on each encoder so SPS/PPS go into extradata (not inlined in keyframes)
 - Collects raw packets in memory as `Packet[]` — no temp files or intermediate container
@@ -200,7 +200,7 @@ The manifest is serialized as a compact flat number array: each frame is 4 conse
 ### Muxer (Node.js only — `src/core/Muxer.ts`)
 
 - Accepts `Packet[]` arrays from Converter (no container demuxing)
-- Converts Annex B → AVCC bitstream for H.264/H.265 packets (VP8/VP9 pass through unchanged)
+- Converts Annex B → AVCC bitstream for H.264/H.265 packets
 - Packs packets and manifest directly into FSV binary format
 - Reads width/height from `config.codedWidth`/`config.codedHeight` for manifest serialization
 

package.json

@@ -66,6 +66,10 @@
       "import": "./dist/cli/main.mjs",
       "require": "./dist/cli/main.cjs"
     },
+    "./core/Codec": {
+      "import": "./dist/core/Codec.mjs",
+      "require": "./dist/core/Codec.cjs"
+    },
     "./core/Converter": {
       "import": "./dist/core/Converter.mjs",
       "require": "./dist/core/Converter.cjs"

readme.md

@@ -4,6 +4,11 @@ FSV (short for "Fast Scrubbing Video") is a video format optimized for fast
 scrubbing on the web, supporting alpha channel. It has been inspired by the
 [ActiveFrame](https://github.com/activetheory/activeframe) project.
 
+More specifically, FSV is a container for h264 and h265. It is designed to be
+easily demuxable on the browser, and contains additional metadata to allow for
+frame-accurate scrubbing and efficient seeking. See the [format](#format)
+section for more details.
+
 [See the demo](https://plutotcool-fsv.vercel.app)
 
 <img src="demo.gif" width="320" height="307"/>
@@ -78,8 +83,8 @@ await Converter.convert('input.webm', 'output.fsv', {
 
 The input file codec is automatically detected if not provided. Yet the
 conversion may fail (especially for alpha videos) if the input codec is not
-compatible with the conversion process. For VP8/VP9 videos, you may need to
-explicitly set the input codec to `libvpx-vp8` or `libvpx-vp9`.
+compatible with the conversion process. For VP8/VP9 input videos, you may
+need to explicitly set the input codec to `libvpx-vp8` or `libvpx-vp9`.
 
 ## Rendering
 

src/cli/convert.ts

@@ -1,5 +1,6 @@
 import { defineCommand } from 'citty'
-import { Converter, FF_ENCODER_LIBX264, type ConvertOptions } from '~/core/Converter'
+import { Converter, type ConvertOptions } from '~/core/Converter'
+import { resolveCodec } from '~/core/Codec'
 import { Logger } from '~/core/Logger'
 
 export default defineCommand({
@@ -26,7 +27,7 @@ export default defineCommand({
     },
     'output-codec': {
       type: 'string',
-      default: FF_ENCODER_LIBX264,
+      default: 'libx264',
       valueHint: 'codec',
       description: 'Codec to use for encoding the video tracks.'
     },
@@ -60,7 +61,7 @@ export default defineCommand({
       }),
 
       alpha: args.alpha,
-      outputCodec: args['output-codec'],
+      outputCodec: resolveCodec(args['output-codec']),
       inputCodec: args['input-codec'] === 'auto'
         ? undefined
         : args['input-codec'] as ConvertOptions['inputCodec'],

src/core/Codec.ts

@@ -0,0 +1,38 @@
+import {
+  FF_ENCODER_LIBX264 as H264,
+  FF_ENCODER_LIBX265 as H265
+} from 'node-av/constants'
+
+export const CODECS = [
+  H264,
+  H265
+]
+
+export const DEFAULT_CODEC = H264
+
+export {
+  H264,
+  H265
+}
+
+export type Codec = typeof CODECS[number]
+
+export function isCodec(codec: unknown): codec is Codec {
+  return CODECS.includes(codec as Codec)
+}
+
+export function assertCodec(codec: unknown): asserts codec is Codec {
+  if (!isCodec(codec)) {
+    throw new Error(`Unsupported codec: ${codec}. Supported codecs: ${CODECS}`)
+  }
+}
+
+export function resolveCodec(codec: unknown): Codec {
+  if (!codec) {
+    return DEFAULT_CODEC
+  }
+
+  assertCodec(codec)
+
+  return codec
+}