@blackbelt-technology/pi-dashboard-video-transcription

Transcribe local video/audio files in-place to speaker-diarized SRT subtitles using the Soniox async transcription API. Full TypeScript port of the standalone video-transcription pi skill — no Python. Its only runtime npm dependency is @blackbelt-technology/pi-dashboard-shared (the repo's safe-subprocess wrapper); everything else rides pi's bundled peers.

Exposed two ways:

• pi skill — .pi/skills/video-transcription (triggers like /transcribe).
• CLI bin — pi-transcribe [directory | file ...].

Prerequisites

• ffmpeg and ffprobe on PATH — used for audio extraction from video, duration probing, and chunk slicing. Audio-only files still need ffprobe for the long-recording duration guard.
  • macOS: brew install ffmpeg
  • Ubuntu/Debian: sudo apt install ffmpeg
  • Windows: https://ffmpeg.org/download.html
• SONIOX_API_KEY — resolved from the environment first, then from an optional gitignored .env file (current directory, then the skill dir). No secret is committed in the package.

Install

pi install @blackbelt-technology/pi-dashboard-video-transcription

Delivery is published + opt-in. The package is NOT auto-loaded by the monorepo.

Usage

pi-transcribe                      # scan ~/Movies (default)
pi-transcribe /path/to/recordings  # scan a directory
pi-transcribe a.m4a b.mp4          # transcribe explicit files

• No argument — scans ~/Movies.
• Single directory — scans it for .mkv, .mp4, .m4a, .mp3.
• One or more file paths — transcribes exactly those files.

Discovered files are processed oldest-first by modification time. A file is skipped when a sibling .srt already exists (idempotent). Output .mp3 (extracted audio) and .srt (subtitles) are written alongside each source file.

Environment overrides

Variable	Default	Meaning
SONIOX_API_KEY	(required)	Soniox API key.
MAX_CHUNK_HOURS	4.5	Chunk size for recordings over the Soniox 5 h duration limit.
MAX_AUDIO_MB	200	Reserved size guard; 0 disables.

Long recordings (>5 h)

Soniox enforces a hard per-request limit on audio duration (18000 s / 5 h), independent of file size. Recordings over the limit are split into MAX_CHUNK_HOURS-sized chunks, transcribed separately, and merged into a single SRT with correct absolute timestamps — full coverage, no truncation. Duration is probed via ffprobe since the limit is on duration, not megabytes.

Development

npm test   # vitest: pure-logic + mocked I/O (no network, no binaries)

The bin runs as TypeScript via pi's jiti loader — no build step. Standalone execution outside pi is out of scope for this package.