Video Debug

Video Debug Protocol

When the user provides a path to a video file (.mp4, .mov, .webm, .mkv, or .gif), follow this protocol.

Step 1: Extract frames

Run the extractor against the video path the user gave you:

bash scripts/extract.sh 

The script will:

1. Verify ffmpeg is installed, and if not, offer to install it (you may need to relay a [y/N] prompt to the user).
2. Probe the video's duration, resolution, and estimated scene-change count.
3. Decide whether the video is "small enough to process directly" or "large enough to need a strategy."

Step 2: Handle large videos

If extract.sh exits with code 10, the video is large (currently: duration > 60 seconds). The script will have printed a single JSON line to stdout with this shape:

{"large": true, "duration_seconds": 248.5, "resolution": "1920x1080"}

Surface these numbers to the user and present them with these four options:

• a) Process all frames as-is (may use many tokens).
• b) Sample down to ~30 evenly-distributed frames.
• c) Focus on a specific time range — ask the user for start–end in MM:SS or seconds.
• d) Use a stricter scene threshold (fewer, more distinct frames).

Then re-run with the chosen strategy:

bash scripts/extract.sh  --strategy= [--range=START-END]

For option c, pass --range=MM:SS-MM:SS (or --range=12-30 for raw seconds).

Step 3: Read the timeline

When extract.sh exits with code 0, its last stdout line is the absolute path to a timeline.md file.

1. Read timeline.md. It lists each extracted frame with its timestamp in the source video.
2. Read each frame .jpg in order. Your Read tool natively handles images — open them visually.

Step 4: Correlate with the codebase

• For UI bugs: identify which component is on screen at the moment of the glitch. Use Glob and Grep to locate that component in the user's project. Inspect the relevant CSS, layout, state hooks, or animation logic.
• For terminal/console errors: read the error text directly off the frame. Search the codebase for the stack-trace symbols.
• For state bugs: look at what differs between consecutive frames. The change between frame N and frame N+1 is usually the bug.

Step 5: Propose a fix

Always cite the specific frame timestamps that evidenced the problem. For example:

> At 00:04.12 (frame_003.jpg) the sidebar's transform jumps from translateX(0) to translateX(-100%) instantly instead of animating. The issue is the missing transition-transform utility on ` in components/Sidebar.tsx`.

Triggering this skill

Trigger automatically whenever the user references a video file path in the contexts described in the frontmatter. The user can also invoke this skill explicitly with:

/video-debug 

Treat the explicit invocation identically.

What this skill does NOT do

• No audio transcription. This is a purely visual debugging tool. If the user expects voice-narrated analysis, tell them this skill doesn't transcribe audio.
• No OCR pre-pass. Read text directly from frames using your multimodal Read capability.
• No frame editing, annotation, or re-encoding. Frames are read-only.

Failure modes to handle

• Video file doesn't exist → extract.sh exits 2. Ask the user to re-check the path.
• Unsupported container → extract.sh exits 3. Tell the user which extensions are supported.
• ffmpeg install declined by user → extract.sh exits 4. Point the user at https://ffmpeg.org/download.html.
• No scene changes detected → extract.sh will emit a single representative frame from the middle of the video and note this in timeline.md. Tell the user the video looked static.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: vladzima
• Source: vladzima/video-debug
• License: MIT

Install and usage instructions live in the source repository linked above.