keisei/KeiSeiKit-1.0
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
KeiSeiKit-1.0/_primitives/_rust/kei-tts
History
Parfii-bot cb59b77ed2 feat(kei-tts + kei-stt): TTS/STT abstractions with 4+3 backends 
Two parallel atomars in the kei-buddy phase-1 plan. Mirror each other's
architecture: trait + feature-gated backend modules + env-driven dispatch
+ wiremock tests for HTTP backends + subprocess-error test for local.

## kei-tts (text-to-speech)
LOC: 959 across 15 files (largest src/lib.rs 121).
Trait `TtsBackend` + 4 backends behind feature flags:
  * elevenlabs — POST api.elevenlabs.io/v1/text-to-speech/{voice}/stream
  * openai     — POST api.openai.com/v1/audio/speech (tts-1, tts-1-hd)
  * google     — POST texttospeech.googleapis.com/v1/text:synthesize
                 (Wavenet voices, base64 audioContent)
  * piper      — local subprocess to piper-tts binary, raw PCM out
Default features: ["piper"]. all-backends feature gates the rest.
`from_env()` reads KEI_TTS_BACKEND (default piper). Returns Box<dyn TtsBackend>.
Tests: 9 passed (env routing + 3 wiremock backends + piper subprocess error).

## kei-stt (speech-to-text)
LOC: 935 across 13 files (largest whisper_local.rs 181).
Trait `SttBackend` + 3 backends:
  * whisper-local  — subprocess to `whisper` CLI / faster-whisper,
                     reads JSON output, parses segments
  * deepgram       — POST api.deepgram.com/v1/listen (Token auth header,
                     raw audio body, parses words → Segments)
  * openai-whisper — POST api.openai.com/v1/audio/transcriptions
                     (multipart file + model=whisper-1 +
                      response_format=verbose_json)
Default features: ["whisper-local"]. all-backends gates the rest.
`from_env()` reads KEI_STT_BACKEND (default whisper-local).
Tests: 10 passed + 1 doc-test (env routing + 5 wiremock + 2 JSON parsers
+ 1 subprocess error + 1 auth-header check).

## Common architecture decisions
  * `with_base_url(url)` constructor on each HTTP backend for wiremock
    testability — same pattern as kei-llm-router and kei-notify-telegram.
  * `tempfile` crate added to kei-stt for whisper-local audio scratch.
  * `base64 = { version = "0.22", optional = true }` in kei-tts for
    Google's base64-encoded audioContent.

## Verify-before-commit (RULE 0.13 §)
  * cargo check -p kei-tts (default + all-backends): PASS
  * cargo check -p kei-stt (default + all-backends): PASS
  * cargo test -p kei-tts --features all-backends --lib: 9/0
  * cargo test -p kei-stt --features all-backends --lib: 10/0
  * cargo check --workspace: PASS

STATUS-TRUTH from both agents: shipped=functional, stubs=0,
behaviour-verified=yes.

## Follow-up (deferred, non-blocking)
  * Real backend verification needs API keys for ElevenLabs / OpenAI /
    Google / Deepgram and piper-tts binary + .onnx model on PATH.
  * whisper-local language_detected always None — whisper CLI JSON
    schema differs across versions, parse heuristic to be added.
  * faster-whisper has different JSON schema from openai-whisper;
    current parser covers openai-whisper convention only.
2026-05-12 13:47:35 +08:00
..
src feat(kei-tts + kei-stt): TTS/STT abstractions with 4+3 backends 2026-05-12 13:47:35 +08:00
Cargo.toml feat(kei-tts + kei-stt): TTS/STT abstractions with 4+3 backends 2026-05-12 13:47:35 +08:00
README.md feat(kei-tts + kei-stt): TTS/STT abstractions with 4+3 backends 2026-05-12 13:47:35 +08:00

README.md

kei-tts

Text-to-speech abstraction crate with 4 backends selected at runtime via KEI_TTS_BACKEND. Default backend is piper (local, free, zero latency).

Backend matrix

Backend Feature flag Cost Latency Quality Language coverage
piper piper Free ~50–200 ms Good 20+ language packs
elevenlabs elevenlabs ~$0.30/1k ch 300–600 ms Excellent 30+ languages
openai openai ~$0.015/1k ch 200–500 ms Very good 50+ languages
google google ~$4/1M ch 200–400 ms Very good 40+ languages

Environment variables

Variable Backend Required Description
KEI_TTS_BACKEND all No piper (default) / elevenlabs / openai / google
ELEVENLABS_API_KEY elevenlabs Yes ElevenLabs API key
OPENAI_API_KEY openai Yes OpenAI API key
KEI_TTS_OPENAI_MODEL openai No tts-1 (default) or tts-1-hd
GOOGLE_TTS_API_KEY google Yes Google Cloud API key
KEI_TTS_PIPER_MODEL piper Yes Path to .onnx piper model file
KEI_TTS_PIPER_BINARY piper No Path to piper-tts (default: PATH)

Usage

[dependencies]
kei-tts = { path = "../kei-tts", features = ["piper"] }

#[tokio::main]
async fn main() -> Result<(), kei_tts::TtsError> {
    let backend = kei_tts::from_env()?;
    let req = kei_tts::TtsRequest::new("Hello, world!");
    let resp = backend.synth(&req).await?;
    std::fs::write("out.mp3", &resp.audio_bytes).ok();
    println!("synthesised {} bytes via {}", resp.audio_bytes.len(), backend.name());
    Ok(())
}

Compile-time features

# All backends:
kei-tts = { features = ["all-backends"] }
# Cloud only, no piper:
kei-tts = { features = ["elevenlabs", "openai", "google"], default-features = false }