Speech

Speech

Use Drawcall Speech for spoken output: NPC dialogue, narration, tutorial voice, accessibility readouts, and UI voice lines. It turns text into an audio clip URL that an app can load and play.

Endpoint

Drawcall Speech turns text into an audio URL.

GET https://v1.speech.drawcall.ai/?text=Hello+world&voice=Zephyr

• text: required, URL-encoded, trimmed, max 1000 chars.
• style: optional, URL-encoded, trimmed, max 1000 chars. Use it for delivery instructions such as tone, emotion, accent, pace, and pauses.
• voice: optional, URL-encoded, defaults to Zephyr.
• Unknown voice names also fall back to Zephyr; put character roles and delivery notes in style.
• Response: audio file, usually audio/wav.
• Cache: generated clips are cached by text, style, and voice; reuse identical URLs for repeatable playback.
• Errors: plain text 400 for invalid input, 502 for generation failures.

Style

Use text and voice for ordinary lines. Add style only when a whole line or clip needs broad delivery guidance. This follows the common TTS split: transcript text is separate from voice selection, while delivery control is optional. style is Drawcall Speech's public name for natural-language delivery instructions; it is a convenience name rather than a universal TTS standard, but it maps well to Gemini style prompts and Azure-style SSML naming without exposing model prompt mechanics.

Keep the words to speak in text, and put line-level delivery notes in style when the whole line needs tone, emotion, accent, pace, or pauses. If all control is local to specific words or beats, inline stage directions in text are usually enough and a separate style is not needed. Style is best-effort rather than sample-accurate timing; for exact timing, pre-generate and edit audio assets.

Good style values:

• Say warmly and excitedly, with a long pause after the first sentence.
• Read this as a spooky whisper, slowly, with a nervous laugh near the end.
• Use a calm British narrator tone and leave a short pause between clauses.

Inline stage directions in text are better for local changes at specific points. Use bracketed directions such as [pause], [long pause], [whispers], [shouting], [happy], [sad], [laughs], or [very slow]. The service asks the model to treat bracketed directions as performance notes rather than spoken words, but this is still model-dependent. Put broad direction in style; put timed or local switches in text.

GET https://v1.speech.drawcall.ai/?text=Hello+from+Drawcall.+Now+we+continue.&voice=Puck&style=Say+warmly+and+excitedly,+with+a+long+dramatic+pause+after+the+first+sentence.

GET https://v1.speech.drawcall.ai/?text=[whispers]+I+found+it.+[long+pause]+[shouting]+Run+now!&voice=Puck&style=Start+tense,+then+turn+urgent.

First Request Delay

The first time a specific text, style, and voice combination is requested, the endpoint has to generate the clip before it can serve it. That short delay can corrupt in-app behavior if a test expects instant playback, animation sync, or deterministic timing.

If that matters, warm the cache before testing by calling the endpoint once for each needed line, style, and voice. Later requests for the same URL are cached and should be instant.

For tighter control, download and store the audio files locally, then serve them from the app. A good middle ground is a small speech script that predownloads every line while keeping the voice line text in one source file, so changing a line remains a single source change.

Examples

HTML audio:

<audio
  controls
  src="https://v1.speech.drawcall.ai/?text=Welcome+to+Drawcall&voice=Zephyr"
></audio>

Three.js positional audio:

import * as THREE from "three";

const listener = new THREE.AudioListener();
camera.add(listener);

const speaker = new THREE.Object3D();
speaker.position.set(2, 1.5, -3);
scene.add(speaker);

const audio = new THREE.PositionalAudio(listener);
audio.setRefDistance(2);
audio.setRolloffFactor(1.5);
speaker.add(audio);

const text = encodeURIComponent("I am speaking from over here.");
const voice = encodeURIComponent("Puck");
new THREE.AudioLoader().load(
  `https://v1.speech.drawcall.ai/?text=${text}&voice=${voice}`,
  (buffer) => {
    audio.setBuffer(buffer);
    audio.setVolume(1);
    audio.play();
  },
);

Voice

Known voices include Zephyr, Puck, Charon, Kore, Fenrir, Leda, Orus, Aoede, Callirrhoe, Autonoe, Enceladus, Iapetus, Umbriel, Algieba, Despina, Erinome, Algenib, Rasalgethi, Laomedeia, Achernar, Alnilam, Schedar, Gacrux, Pulcherrima, Achird, Zubenelgenubi, Vindemiatrix, Sadachbia, Sadaltager, and Sulafat.

Browsers usually require a click/tap before audio can play. In UI, start playback from a user gesture and resume the audio context first if needed.