Uloop Record Video

Task

Record the Unity Game View while Play Mode is running, or any Editor window with --window-name, then hand the file path to the user or inspect frames from it.

Workflow

1. For a Game View recording, ensure Play Mode is running (uloop control-play-mode --action Play) and the Game View is open; start fails in Edit Mode. With --window-name the recording targets that Editor window instead and needs no Play Mode.
2. uloop record-video --action start [options]. It returns immediately; encoding continues inside the Editor.
3. Drive the scene with other uloop commands (simulate-keyboard, simulate-mouse-input, replay-input, ...). Do not run uloop compile mid-recording: a compile that runs auto-stops and finalizes the file (when Unity's Script Changes While Playing is Recompile After Finished Playing, the compile is refused instead and the recording continues). Exiting Play Mode also auto-stops a Game View recording; a --window-name recording keeps running when Play Mode stops.
4. uloop record-video --action stop. The file is playable only after this call (or after an auto-stop).
5. Read OutputPath from the JSON and use exactly that path. The output directory holds earlier recordings too (the newest 20 per extension are kept), so ls -t can pick a stale file.
6. To inspect the content yourself, extract stills with ffmpeg (e.g. ffmpeg -i "<OutputPath>" -vf fps=1 frames_%03d.png) and view the PNGs. Otherwise report the path and duration to the user.

Tool Reference

bashCopy code
uloop record-video --action start [--frame-rate <fps>] [--max-duration-seconds <sec>] [--resolution-scale <0.1-1.0>] [--quality <low|medium|high>] [--window-name <name>] [--match-mode <exact|prefix|contains>] [--output-path <file>]
uloop record-video --action status
uloop record-video --action stop

Parameters

Actions

Output

Returns JSON containing:

• Success: Whether the request completed.
• Message: Human-readable status.
• Action: Echoes the executed action.
• IsRecording: Whether a recording is active after this call.
• OutputPath: Absolute path of the video file. Open this path; do not search the directory. A window recording uses the window_ name prefix instead of gameview_.
• Width / Height: Encoded resolution after --resolution-scale and even rounding (0 when none).
• FrameRate: Output fps (0 when none).
• Quality: Bitrate preset in use.
• EncodedFrameCount: Frames written to the encoder.
• SkippedFrameCount: Frame slots that could not be captured (Game View closed or resized, or encoder refused a frame). The video keeps its timeline; skipped slots are simply missing.
• ElapsedSeconds: Seconds since start (frozen after stop).
• StoppedBy: Why the recording ended — "cli", "max-duration", "play-mode-exit", "window-closed", "assembly-reload", or "editor-quit". Omitted while recording.

Interpreting results

• Success: false with Message "A recording is already in progress" → run stop first, then start again.
• Success: false with "Play Mode view RenderTexture is not available" → open the Game View tab (uloop focus-window) and make sure a camera renders.
• SkippedFrameCount growing while EncodedFrameCount stays flat → the Game View is closed, hidden, or resized. Restore it; recording resumes without restarting.
• EncodedFrameCount far below ElapsedSeconds × FrameRate with few skips → the Editor is unfocused and throttling draws; run uloop focus-window before the next recording.
• Success: false with "Window '...' not found" → pick the right title from the Open windows: list in the message, or use --match-mode prefix.
• StoppedBy is not "cli" → the recording ended on its own; the file is still valid up to that point.

Notes

• Odd Game View sizes are rounded down to even for H.264 (for example 1286×723 → 1286×722; the last pixel row/column is dropped).
• The recording is wall-clock paced, so Play Mode pause records a still image, not a gap.
• A window recording survives Play Mode stopping, but entering Play Mode with domain reload enabled (Unity's default) ends it with StoppedBy: "assembly-reload".
• Default output is H.264 .mp4 on macOS/Windows and VP8 .webm on Linux. An explicit .webm path uses VP8 on every host.
• Default recordings under .uloop/outputs/Videos/ keep only the newest 20 files per extension; a custom --output-path is never pruned.