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Betamax

Differences from VHS

Betamax supports VHS-style tape files with typed input, waits, themes, frame styling, GIF output, and screenshots. This page lists the differences to consider when moving tapes from VHS.

Summary

Section titled “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

Section titled “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

Section titled “Intentional omissions”

record, serve, and publish are not planned for the first stable release. Betamax focuses on 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

Section titled “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

Section titled “Video tradeoff”

MP4 and WebM use ffmpeg, so video output requires it on PATH. Betamax handles GIF, PNG, screenshots, terminal parsing, rendering, and state JSON in process.

Use Outputs for installation notes and output selection guidance.