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POST
/
api
/
v1
/
lightning-v2
/
stream
Generate speech from text (Lightning v2)
curl --request POST \
  --url https://waves-api.smallest.ai/api/v1/lightning-v2/stream \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "text": "<string>",
  "voice_id": "<string>",
  "sample_rate": 24000,
  "speed": 1,
  "consistency": 0.5,
  "similarity": 0,
  "enhancement": 1,
  "language": "en",
  "output_format": "pcm",
  "pronunciation_dicts": [
    "<string>"
  ]
}
'
{
  "data": "event: chunk\ndata: <WAV_DATA>\ndone: false\n"
}

​
Overview

The Lightning v2 SSE API provides real-time text-to-speech streaming capabilities with high-quality voice synthesis. This API uses Server-Sent Events (SSE) to deliver audio chunks as they’re generated, enabling low-latency audio playback without waiting for the entire audio file to process. For an end-to-end example of how to use the Lightning v2 SSE API, check out Text to Speech (SSE) Example

​
When to Use

  • Interactive Applications: Perfect for chatbots, virtual assistants, and other applications requiring immediate voice responses
  • Long-Form Content: Efficiently stream audio for articles, stories, or other long-form content without buffering delays
  • Voice User Interfaces: Create natural-sounding voice interfaces with minimal perceived latency
  • Accessibility Solutions: Provide real-time audio versions of written content for users with visual impairments

​
How It Works

  1. Make a POST Request: Send your text and voice settings to the API endpoint
  2. Receive Audio Chunks: The API processes your text and streams audio back as base64-encoded chunks with 1024 byte size
  3. Process the Stream: Handle the SSE events to decode and play audio chunks sequentially
  4. End of Stream: The API sends a completion event when all audio has been delivered

Authorizations

​
Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json
​
text
string
required

The text to convert to speech.

​
voice_id
string
required

The voice identifier to use for speech generation.

​
sample_rate
integer
default:24000

The sample rate for the generated audio.

Required range: 8000 <= x <= 24000
​
speed
number
default:1

The speed of the generated speech.

Required range: 0.5 <= x <= 2
​
consistency
number
default:0.5

This parameter controls word repetition and skipping. Decrease it to prevent skipped words, and increase it to prevent repetition.

Required range: 0 <= x <= 1
​
similarity
number
default:0

This parameter controls the similarity between the generated speech and the reference audio. Increase it to make the speech more similar to the reference audio.

Required range: 0 <= x <= 1
​
enhancement
number
default:1

Enhances speech quality at the cost of increased latency.

Required range: 0 <= x <= 2
​
language
enum<string>
default:en

Determines how numbers are spelled out. If set to 'en', numbers will be read as individual digits in English. If set to 'hi', numbers will be read as individual digits in Hindi.

Available options:
en,
hi,
ta,
kn,
mr,
bn,
gu,
ar,
he,
fr,
de,
pl,
ru,
it,
nl,
es,
sv,
ml,
te
​
output_format
enum<string>
default:pcm

The format of the output audio.

Available options:
pcm,
mp3,
wav,
mulaw
​
pronunciation_dicts
string[]

The IDs of the pronunciation dictionaries to use for speech generation.

The ID of the pronunciation dictionary to use for speech generation.

Response

Synthesized speech retrieved successfully.