stt_ime - Speech-to-Text Input Method for Fcitx5

Local, privacy-preserving speech-to-text that integrates as a native Fcitx5 input method.

Components

stt-stream: Rust CLI that captures audio, runs VAD, and transcribes with Whisper
fcitx5-stt: C++ Fcitx5 addon that spawns stt-stream and commits text to apps

Modes

Manual: Press Ctrl+Space or Ctrl+R to start/stop recording
Oneshot: Automatically starts on speech, commits on silence, then resets
Continuous: Always listening, commits each utterance automatically

Press Ctrl+M while STT is active to cycle between modes.

Keys (when STT input method is active)

Key	Action
`Ctrl+Space` / `Ctrl+R`	Toggle recording (manual mode)
`Ctrl+M`	Cycle mode (manual → oneshot → continuous)
`Enter`	Accept current preedit text
`Escape`	Cancel recording / clear preedit

Usage

NixOS Module

# In your host's flake.nix inputs:
stt_ime.url = "git+https://git.ros.one/josh/nixos-config?dir=flakes/stt_ime";

# In your NixOS config:
{
  imports = [ inputs.stt_ime.nixosModules.default ];

  ringofstorms.sttIme = {
    enable = true;
    model = "base.en";  # tiny, base, small, medium, large-v3 (add .en for English-only)
    useGpu = false;     # set true for CUDA acceleration
  };
}

Standalone CLI

# Run with default settings (manual mode)
stt-stream

# Run in continuous mode
stt-stream --mode continuous

# Use a specific model
stt-stream --model small-en

# Commands via stdin (manual mode):
echo "start" | stt-stream  # begin recording
echo "stop" | stt-stream   # stop and transcribe
echo "cancel" | stt-stream # cancel without transcribing
echo "shutdown" | stt-stream # exit

Output Format (NDJSON)

{"type":"ready"}
{"type":"recording_started"}
{"type":"partial","text":"hello worl"}
{"type":"partial","text":"hello world"}
{"type":"final","text":"Hello world."}
{"type":"recording_stopped"}
{"type":"shutdown"}

Models

Models are automatically downloaded from Hugging Face on first run and cached in ~/.cache/stt-stream/models/.

Model	Size	Speed	Quality
tiny.en	~75MB	Fastest	Basic
base.en	~150MB	Fast	Good (default)
small.en	~500MB	Medium	Better
medium.en	~1.5GB	Slow	Great
large-v3	~3GB	Slowest	Best (multilingual)

Environment Variables

STT_STREAM_MODEL_PATH: Path to a specific model file
STT_STREAM_MODEL: Model name (overridden by CLI)
STT_STREAM_USE_GPU: Set to "1" for GPU acceleration

Building

cd flakes/stt_ime
nix build .#stt-stream    # Rust CLI only
nix build .#fcitx5-stt    # Fcitx5 addon (includes stt-stream)
nix build                  # Default: fcitx5-stt

Integration with de_plasma

The addon is automatically added to Fcitx5 when ringofstorms.sttIme.enable = true. It appears as "Speech to Text" (STT) in the input method switcher alongside US and Mozc.

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