Lightning v3.1 (endpoint will be deprecated)

<Warning>**Endpoint scheduled for retirement.** This URL will stop accepting requests **60 days from the Lightning v3.1 Pro launch (2026-05-15)** — i.e. on **2026-07-14**. The Lightning v3.1 model itself is current and stays. Migrate to [`POST /waves/v1/tts`](/waves/api-reference/api-reference/text-to-speech/synthesize-speech) and select Lightning v3.1 via the `model` body field (default).</Warning> Synthesize speech from text in a single request. The simplest way to get audio when you have the full text up front — pass `text` + `voice_id`, get back binary audio. ## When to use this - **Use this** for short utterances you can render before playback (notifications, prompts, batch jobs, audio file generation). - **Use the SSE streaming endpoint** when you want playback to start before the full audio is ready (long passages, latency-sensitive apps). - **Use the WebSocket endpoint** when text arrives incrementally (LLM token streams, live captioning). ## Key features - 44 kHz natural, expressive synthesis - Cloned voice IDs (`voice_*`) work — same param as catalog voices - 12 documented languages — see the model card for the full list - Output formats: `pcm`, `mp3`, `wav`, `ulaw`, `alaw` - Sample rates: 8 kHz – 44.1 kHz - Speed: 0.5× – 2× - Per-call pronunciation dictionaries via `pronunciation_dicts` ## Examples **cURL** ```bash curl -X POST "https://api.smallest.ai/waves/v1/lightning-v3.1/get_speech" \ -H "Authorization: Bearer $SMALLEST_API_KEY" \ -H "Content-Type: application/json" \ -H "Accept: audio/wav" \ -d '{ "text": "Hello from Lightning v3.1.", "voice_id": "magnus", "sample_rate": 24000, "output_format": "wav" }' --output speech.wav ``` **Python** (`pip install smallestai>=4.4.0`) ```python from smallestai import SmallestAI client = SmallestAI(token="YOUR_API_KEY") with open("speech.wav", "wb") as f: for chunk in client.waves.synthesize_lightning_v3_1( text="Hello from Lightning v3.1.", voice_id="magnus", sample_rate=24000, output_format="wav", # Optional: cloned voice support # voice_id="voice_FlPKRWI7DX", # Optional: pin pronunciations for specific words # pronunciation_dicts=["<your dict id>"], ): f.write(chunk) ``` **JavaScript / TypeScript** (using `fetch`) ```typescript const res = await fetch("https://api.smallest.ai/waves/v1/lightning-v3.1/get_speech", { method: "POST", headers: { Authorization: `Bearer ${process.env.SMALLEST_API_KEY}`, "Content-Type": "application/json", Accept: "audio/wav", }, body: JSON.stringify({ text: "Hello from Lightning v3.1.", voice_id: "magnus", sample_rate: 24000, output_format: "wav", }), }); const audio = Buffer.from(await res.arrayBuffer()); require("node:fs").writeFileSync("speech.wav", audio); ``` ## Common gotchas - **Set `Accept: audio/wav`.** Omitting it can return an empty or unplayable response. - **Cloned voices** (`voice_*` from `add_voice`) work on this endpoint and support `pronunciation_dicts`. - **`pronunciation_dicts` validates IDs at request time.** Passing an unknown ID returns `Invalid input data` — create the dict first via the pronunciation-dicts endpoint and save the returned `id`. - **Pronunciation matching is case-sensitive.** Add both `Synopsis` and `synopsis` if your text uses both casings. - **44.1 kHz output** is supported but most playback environments are happy with 24 kHz — drop the sample rate if bandwidth matters. - **JavaScript / TypeScript**: the official `smallestai` npm package predates Lightning v3.1, so call this endpoint with `fetch` or `axios` as shown above.