Call Model — STT on edge

Call Model (call_model) nodes that select an edge or hybrid speech-to-text catalog model run inference on-device via cw.models.load(...).predict(...). Cloud-only STT uses client.mlmodels.run(...) and does not require edge STT packages.

Prompting for STT models is optional biasing — see Prompting Call Model.

Catalog models and dependencies

Each STT seed sets one SDK extra in metadata.edge_package. Edge-sync surfaces it in model_requirements.

Model	Runtime	Edge extra	Install
Whisper Tiny EN Q5_1	`whisper_cpp`	`ml-stt`	`pip install 'cyberwave[ml-stt]'`
Whisper Base EN Q5_1	`whisper_cpp`	`ml-stt`	same
Whisper Small EN Q5_1	`whisper_cpp`	`ml-stt`	same
Whisper Tiny Multilingual Q5_1	`whisper_cpp`	`ml-stt`	same (+ cloud fallback)
Whisper Base Multilingual Q5_1	`whisper_cpp`	`ml-stt`	same (+ cloud fallback)
Faster Whisper Tiny EN	`faster_whisper`	`ml-stt-faster`	`pip install 'cyberwave[ml-stt-faster]'`
Faster Whisper Base EN	`faster_whisper`	`ml-stt-faster`	same
Faster Whisper Small EN	`faster_whisper`	`ml-stt-faster`	same

Do not point catalog metadata at ml-all. Pick the extra for the runtime you use.

Weight paths (`edge_model_path`)

Model family	Cache / load path	Notes
whisper.cpp	File path to GGML binary, e.g. `models/whisper/ggml-tiny.en-q5_1.bin`	`download_url` in metadata; first run fetches into edge model cache
faster-whisper	Cache key = `model_external_id` (e.g. `tiny.en`); `metadata.edge_model_path` is documentation only	Edge Core pre-downloads via catalog `model_external_id`; CTranslate2 cache under `/app/models/tiny.en/`

Generated workers emit:

model = cw.models.load(
    "tiny.en",
    runtime="faster_whisper",
    faster_whisper_model_id="tiny.en",
    download_root="tiny.en",
    ...
)

Compile server

When a workflow has run_on_edge: true and a Call Model node references an on-device STT model, compile verifies imports:

Runtime	Import checked	`base.txt` package
`whisper_cpp`	`pywhispercpp.model.Model`	`pywhispercpp==1.4.1`
`faster_whisper`	`faster_whisper.WhisperModel`	`faster-whisper>=1.1.1`

Failure example:

This workflow uses Call Model with faster-whisper but faster-whisper is not installed on the compile server. Install faster-whisper (or cyberwave[ml-stt-faster]) on Django before compiling for edge.

Rebuild Django after updating requirements/base.txt — see Edge workflow dependencies.

Edge worker

Install the catalog model’s extra (ml-stt or ml-stt-faster).
Sync workflow — edge-sync lists model_requirements with edge_model_path.
First inference downloads weights (or uses pre-staged files under ~/.cyberwave/models/).

Audio input: int16 PCM @ 16 kHz mono (or WAV bytes). The worker passes sample_rate_hz, channels, and optional language / task / vad_filter (Faster Whisper built-in VAD when enabled).

Choosing whisper.cpp vs Faster Whisper

	whisper.cpp (`ml-stt`)	Faster Whisper (`ml-stt-faster`)
Hardware	Raspberry Pi 4 class	Pi 4+; Jetson/GPU for Base/Small
Weights	Quantized GGML (`.bin`)	CTranslate2 cache dir
Latency	Good for Tiny on CPU	Tiny EN optimized for real-time
Built-in VAD	No (use Audio Assistant upstream)	Yes (`builtin_vad_filter` on catalog)

Typical wiring

audio_track → audio_assistant → wake_word_engine (optional)
  → call_model (STT catalog model)
  → fuzzy_matcher ← twin
  → virtual_controller

Wire Call Model audio input from upstream audio key. Wire result (text) into Fuzzy Matcher’s Uncertain String (query).

Edge dependencies

Full matrix (all nodes + compile server)

Audio in Workflows

PCM format and pipelines

Fuzzy Matcher

Map STT text to commands

Concepts

Platform Features

Cyberwave Edge

Technical Reference

Use-Case Recipes

Call Model — STT on edge

Catalog models and dependencies

Weight paths (`edge_model_path`)

Compile server

Edge worker

Choosing whisper.cpp vs Faster Whisper

Typical wiring

Edge dependencies

Audio in Workflows

Fuzzy Matcher

​Catalog models and dependencies

​Weight paths (edge_model_path)

​Compile server

​Edge worker

​Choosing whisper.cpp vs Faster Whisper

​Typical wiring

​Related

Edge dependencies

Audio in Workflows

Fuzzy Matcher

Catalog models and dependencies

Weight paths (`edge_model_path`)

Compile server

Edge worker

Choosing whisper.cpp vs Faster Whisper

Typical wiring

Related