Differences From VHS

Betamax follows the useful parts of the VHS authoring model: tape files, typed input, waits, themes, frame styling, GIF output, screenshots, and simple examples. The differences below focus on actual user-visible behavior, not implementation details that produce the same result.

Summary

Area	VHS	Betamax
Terminal stack	Browser terminal stack	PTY plus libghostty-vt, rendered in process
GIF and PNG	Supported	Supported in process
MP4 and WebM	Supported	Supported through ffmpeg
State snapshots	Not a primary feature	JSON viewport, scrollback, cursor, and styles
Source	Executes included tapes	Parsed, then rejected with a clear not-implemented error
record	Records interactive sessions	Intentionally not implemented
serve	Starts a server workflow	Intentionally not implemented
publish	Upload/share workflow	Intentionally not implemented

Same Authoring Ideas

The core tape flow should feel familiar if you know VHS:

• Output declares artifacts.
• Set controls dimensions, theme, timing, typography, and frame styling.
• Type, Enter, key commands, Sleep, and waits drive the terminal.
• Hide and Show keep setup or teardown out of the final animation.
• Screenshot writes checkpoint PNGs.

Betamax also keeps the simple recording-shell idea. Common shells are started in a cleaner recording environment where possible so the default prompt is stable and VHS-like instead of a host-specific shell prompt.

Intentional Omissions

record, serve, and publish are not planned for the first stable shape. They add product and service surface area that is separate from Betamax’s primary goal: deterministic local rendering and terminal testing.

Source is parsed because existing VHS tapes may contain it. Betamax fails explicitly when running such a tape so users get a targeted migration error instead of an unknown command or silent skip.

Betamax Additions

State JSON is the main addition. Output demo.json writes final terminal state, and State checkpoint.json writes state at a specific point in the tape. The format includes plain text for easy assertions plus compact styled spans for style-aware snapshot tests.

See Terminal Testing and State JSON for that workflow.

Video Tradeoff

MP4 and WebM use ffmpeg. That keeps container encoding reliable and avoids adding native video encoder complexity to the first cut. GIF, PNG, screenshots, terminal parsing, rasterization, and state JSON are still handled in process.

Use Outputs for installation notes and output selection guidance.