# STT: Google Speech-to-Text v2 / Chirp Evaluation (follow-up)

Status: **in progress** — interactive benchmark page available for SysAdmin (2026-05-15).

Related: gateway `connectorVoiceGoogle.py` uses Speech v1 `SpeechClient` only.

## Goal

Benchmark STT v2 (e.g. Chirp / Chirp 2) for `de-DE` vs current v1 `latest_short` / `latest_long` on:

- Latency (time-to-first-token, final latency)
- WER / subjective quality in meeting + coaching scenarios
- Cost and quota

## Current State (2026-05-15)

- **Interactive benchmark page** added: `Administration > System > STT Benchmark` (SysAdmin only).
  - Upload or record audio; runs v1 and v2 (Chirp 2) simultaneously; shows transcription, confidence, latency side-by-side.
  - Configurable: language, v1 model, v2 model, v2 region.
  - Backend: `routeAdminSttBenchmark.py` using `google.cloud.speech` (v1) + `google.cloud.speech_v2` (v2).
  - Frontend: `SttBenchmarkPage.tsx` under `/admin/stt-benchmark`.
- **Production switch not yet done** — `connectorVoiceGoogle.py` still uses v1 only.

## Next Steps

1. Run benchmark with real meeting/coaching audio samples across `de-DE`, `de-CH`, `en-US`.
2. Compare latency + quality. Document in this file.
3. If Chirp 2 wins: add v2 client path to `connectorVoiceGoogle.py` behind feature flag.
4. Run A/B on CommCoach streaming and Teamsbot batch paths with identical audio fixtures.
5. Document decision in `wiki/b-reference/` and remove flag or make v2 default.

## Notes

- Streaming and batch config differ between v1 and v2; keep `VoiceObjects` as the single facade.
- Billing hooks (`calculateSttCostCHF`) must use measured duration (see streaming `result_end_time`), not compressed byte heuristics.
- `google-cloud-speech==2.21.0` includes `speech_v2` module — no dependency upgrade needed.
- Chirp 2 is v2-only and requires regional endpoint (`{location}-speech.googleapis.com`).