# Homepage Video Assets

> Homepage Video Assets is an Agent Skill for documents published in the remotion-dev/remotion repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Use when rendering or replacing Remotion homepage creator strip videos, especially transparent Chrome WebM and Safari MP4 assets copied into both promo-pages and docs.

- Skill name: `homepage-video-assets`
- Category: [Documents](https://www.openparable.com/skill/documents/1)
- Source: https://github.com/remotion-dev/remotion/blob/HEAD/.agents/skills/homepage-video-assets/SKILL.md
- Repository: remotion-dev/remotion (53,319 GitHub stars when collected)

## SKILL.md

# Homepage Video Assets

Use this workflow for homepage creator strip assets such as:

- `homepage-assets-master`
- `editing-vp9-chrome` / `editing-safari`
- `what-is-remotion`

## Workflow

1. Render a fresh transparent ProRes 4444 master from `packages/brand`.

```bash
cd packages/brand
bunx remotion render <composition-id> /tmp/<asset>-master.mov \
  --codec=prores \
  --prores-profile=4444 \
  --pixel-format=yuva444p10le \
  --image-format=png \
  --timeout=120000 \
  --overwrite
```

2. Convert from the ProRes master, not from a previous WebM/MOV.

Chrome WebM:

```bash
ffmpeg -y -i /tmp/<asset>-master.mov \
  -vf scale=540:540 \
  -c:v libvpx \
  -pix_fmt yuva420p \
  -auto-alt-ref 0 \
  -an /tmp/<chrome-name>.webm
```

Safari MP4:

```bash
ffmpeg -y -i /tmp/<asset>-master.mov \
  -vf scale=540:540 \
  -c:v prores_ks \
  -profile:v 4 \
  -pix_fmt yuva444p10le \
  -an /tmp/<asset>-540-prores.mov

avconvert \
  --source /tmp/<asset>-540-prores.mov \
  --preset PresetHEVCHighestQualityWithAlpha \
  --output /tmp/<safari-name>.mp4 \
  --replace
```

3. Copy both outputs into both app folders:

```bash
cp /tmp/<chrome-name>.webm ../promo-pages/public/img/<chrome-name>.webm
cp /tmp/<safari-name>.mp4 ../promo-pages/public/img/<safari-name>.mp4
cp /tmp/<chrome-name>.webm ../docs/static/img/<chrome-name>.webm
cp /tmp/<safari-name>.mp4 ../docs/static/img/<safari-name>.mp4
```

## Verification

Verify the ProRes master has real alpha before converting, and verify the Safari MP4 exists in both folders:

```bash
ffmpeg -i /tmp/<asset>-master.mov
ffmpeg -i ../promo-pages/public/img/<safari-name>.mp4
ffmpeg -y -i /tmp/<asset>-master.mov \
  -vf alphaextract -frames:v 1 /tmp/<asset>-alpha.png
```

The master should report `prores (4444)` and a `yuva...` pixel format. `alphaextract` should succeed, and the alpha image should not be fully opaque. A common failure mode is `alphaextract` succeeding but every sampled pixel is opaque; in that case, the master was rendered with a black/opaque background or a stale opaque master was reused.

Verify every copied Chrome WebM and Safari MP4 is exactly `540x540`:

```bash
for f in \
  ../promo-pages/public/img/<chrome-name>.webm \
  ../promo-pages/public/img/<safari-name>.mp4 \
  ../docs/static/img/<chrome-name>.webm \
  ../docs/static/img/<safari-name>.mp4; do
  ffmpeg -i "$f"
done
```

The Safari MP4 should look like the known-good file shape: `major_brand: mp42`, `compatible_brands: isommp41mp42`, `Video: hevc (Main) (hvc1)`, `540x540`, and `handler_name: Core Media Video`. If it reports `h264 (avc1)` or dimensions such as `960x540`, it is the wrong file and will render differently in Safari.

Do not add ProRes `.mov` files to the homepage PR; they are too large. Safari should use the small `.mp4` fallback. Chrome should use the transparent `.webm`.

---

Source: https://www.openparable.com/skill/documents/homepage-video-assets (OpenParable). Cite the canonical URL above.