# Check every render before you trust it (free sample)

> One rule, one skill and four ffmpeg commands that make Claude Code or Codex look at its own video output (frames, cuts, loudness, captions) before it tells you it is done.

- URL: https://paperchasewebb.ai/bots/marketplace/items/check-every-render-before-you-trust-it-free-sample/
- Type: Prompt pack
- Category: Creative and video
- By: PaperChaseWebb
- Works with: Claude Code, Codex (named in the listing); Plain .md
- Price: Free USD
- Difficulty: Beginner
- Setup time: 5 min
- Time to result: Five minutes to install
- Format: Markdown (.md) file, check-every-render-before-you-trust-it-free-sample.md
- Version: 1.0, updated 2026-10-26
- License: Personal and commercial use.

## What you end up with

Your agent reports problems with timestamps instead of calling a broken render finished.

## What you get

- The render check rule for AGENTS.md or CLAUDE.md
- A render-checker SKILL.md
- Four ffmpeg commands for frames, loudness and black frames

## Who it is for

Anyone whose agent renders or edits video and says done too early.

## Tools needed

- Claude Code: runs the render-checker skill
- Codex: runs the render-checker skill
- ffmpeg: extracts frames and measures audio
- You need: ffmpeg installed
- You need: A video your agent rendered

Cost to run: Free.

## Sample prompt: Check the render (Claude Code, Codex)

```
Run the render-checker skill on out/[file].
Report each problem with its timestamp and the smallest fix. Do not re-render until I have seen the list.
```

Seeing the list first keeps you in charge of the next render.

## Free preview of check-every-render-before-you-trust-it-free-sample.md

````markdown
# Check every render before you trust it (free sample)

A free sample from Video Production with AI Agents by PaperChaseWebb. Written for Claude Code and Codex.

Coding agents will tell you a video is done the moment ffmpeg exits. The builders in our October 2026 research who got good results made the agent look at its own output first. video-use from the Browser Use team checks every cut point before it shows you anything, and the 3D product spot by @0xFizzu caught a vanished liquid and a floating label in test frames, not in the final render. This sample gives you the rule, the skill and the commands.

## The rule

Add this to AGENTS.md or CLAUDE.md:

```text
Before you report any render as done, run the render-checker skill. Never modify anything in sources/. Never upload or post a video without asking me.
```

## The render-checker skill

Save as `.claude/skills/render-checker/SKILL.md` (Claude Code) or `.agents/skills/render-checker/SKILL.md` (Codex).

```markdown
---
name: render-checker
description: Use before reporting any render as done. Checks frames, cuts and audio against the plan.
---
1. Read SHOTLIST.md if it exists, otherwise ask me what the video should show.
2. Probe the file: duration, size, fps, codec. Compare with the plan.
3. Extract frames at the start, middle and end of every shot, and one frame either side of every cut.
4. Look at each frame: text cut off or overlapped, wrong colors, faces cropped, blank or black frames.
5. Measure loudness and true pe
````

## Worth knowing

- Sampling frames catches most problems but not all. Watch the final file yourself before publishing.

## Questions

**What is in the full pack?** The lane guide, project templates, 16 prompts, three more skills, publishing and privacy checklists, reported render times and 20 video project ideas.

## How to get it

Free sample. Download it directly at https://paperchasewebb.ai/bots/marketplace/items/check-every-render-before-you-trust-it-free-sample/, no signup.

Seller: PaperChaseWebb Inc., mgmt@paperchasewebb.com