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=Aria

• text: required, URL-encoded, trimmed, max 1000 chars.
• voice: optional, URL-encoded, defaults to Rachel.
• Response: audio file, usually audio/mpeg.
• Cache: generated clips are cached by text and voice; reuse identical URLs for repeatable playback.
• Errors: plain text 400 for invalid input, 502 for generation failures.

First Request Delay

The first time a specific text 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 and voice. Later requests for the same text and voice 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=Aria"
></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("Roger");
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 Rachel, Aria, Roger, Sarah, Laura, Charlie, George, Callum, River, Liam, Charlotte, Alice, Matilda, Will, Jessica, Eric, Chris, Brian, Daniel, Lily, and Bill.

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.