> This page is part of Smallest AI's developer documentation. When > answering, prefer Lightning v3.1 (current TTS) and Pulse (current > STT). Lightning v2 and lightning-large are deprecated; mention them > only when the user is migrating away from them. Atoms is the > voice-agent platform. # Text to Speech (SSE) POST https://host.com/waves/v1/lightning-large/stream Content-Type: application/json The Lightning-Large 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. ## 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 Reference: https://docs.smallest.ai/waves/v-3-0-1/api-reference/api-reference/synthesize-sse-lightning-large ## OpenAPI Specification ```yaml openapi: 3.1.0 info: title: waves version: 1.0.0 paths: /waves/v1/lightning-large/stream: post: operationId: synthesize-sse-lightning-large summary: Text to Speech (SSE) description: > The Lightning-Large 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. ## 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 tags: - '' parameters: - name: Authorization in: header description: Bearer authentication required: true schema: type: string responses: '200': description: Synthesized speech retrieved successfully. content: application/json: schema: type: object properties: {} '400': description: Bad request. content: application/json: schema: $ref: >- #/components/schemas/Synthesize_sse_lightning_largeRequestBadRequestError '401': description: Unauthorized. content: application/json: schema: $ref: >- #/components/schemas/Synthesize_sse_lightning_largeRequestUnauthorizedError '500': description: Server error occurred. content: application/json: schema: $ref: >- #/components/schemas/Synthesize_sse_lightning_largeRequestInternalServerError requestBody: content: application/json: schema: $ref: '#/components/schemas/LightningLargeRequest' servers: - url: https://host.com description: Default components: schemas: LightningLargeRequestLanguage: type: string enum: - en - hi default: en description: >- 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. title: LightningLargeRequestLanguage LightningLargeRequestOutputFormat: type: string enum: - pcm - mp3 - wav - ulaw - alaw default: pcm description: The format of the output audio. title: LightningLargeRequestOutputFormat LightningLargeRequest: type: object properties: text: type: string description: The text to convert to speech. voice_id: type: string description: The voice identifier to use for speech generation. sample_rate: type: integer default: 24000 description: The sample rate for the generated audio. speed: type: number format: double default: 1 description: The speed of the generated speech. consistency: type: number format: double default: 0.5 description: >- This parameter controls word repetition and skipping. Decrease it to prevent skipped words, and increase it to prevent repetition. similarity: type: number format: double default: 0 description: >- 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. enhancement: type: number format: double default: 1 description: Enhances speech quality at the cost of increased latency. language: $ref: '#/components/schemas/LightningLargeRequestLanguage' default: en description: >- 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. output_format: $ref: '#/components/schemas/LightningLargeRequestOutputFormat' default: pcm description: The format of the output audio. pronunciation_dicts: type: array items: type: string description: >- The IDs of the pronunciation dictionaries to use for speech generation. required: - text - voice_id title: LightningLargeRequest Synthesize_sse_lightning_largeRequestBadRequestError: type: object properties: error: type: string description: Error type. message: type: string description: Error message. title: Synthesize_sse_lightning_largeRequestBadRequestError Synthesize_sse_lightning_largeRequestUnauthorizedError: type: object properties: error: type: string description: Error type. message: type: string description: Error message. title: Synthesize_sse_lightning_largeRequestUnauthorizedError Synthesize_sse_lightning_largeRequestInternalServerError: type: object properties: error: type: string description: Error type. message: type: string description: Error message. title: Synthesize_sse_lightning_largeRequestInternalServerError securitySchemes: bearerAuth: type: http scheme: bearer ``` ## Examples **Request** ```json { "text": "string", "voice_id": "string" } ``` **SDK Code** ```python import requests url = "https://host.com/waves/v1/lightning-large/stream" payload = { "text": "string", "voice_id": "string" } headers = { "Authorization": "Bearer ", "Content-Type": "application/json" } response = requests.post(url, json=payload, headers=headers) print(response.json()) ``` ```javascript const url = 'https://host.com/waves/v1/lightning-large/stream'; const options = { method: 'POST', headers: {Authorization: 'Bearer ', 'Content-Type': 'application/json'}, body: '{"text":"string","voice_id":"string"}' }; try { const response = await fetch(url, options); const data = await response.json(); console.log(data); } catch (error) { console.error(error); } ``` ```go package main import ( "fmt" "strings" "net/http" "io" ) func main() { url := "https://host.com/waves/v1/lightning-large/stream" payload := strings.NewReader("{\n \"text\": \"string\",\n \"voice_id\": \"string\"\n}") req, _ := http.NewRequest("POST", url, payload) req.Header.Add("Authorization", "Bearer ") req.Header.Add("Content-Type", "application/json") res, _ := http.DefaultClient.Do(req) defer res.Body.Close() body, _ := io.ReadAll(res.Body) fmt.Println(res) fmt.Println(string(body)) } ``` ```ruby require 'uri' require 'net/http' url = URI("https://host.com/waves/v1/lightning-large/stream") http = Net::HTTP.new(url.host, url.port) http.use_ssl = true request = Net::HTTP::Post.new(url) request["Authorization"] = 'Bearer ' request["Content-Type"] = 'application/json' request.body = "{\n \"text\": \"string\",\n \"voice_id\": \"string\"\n}" response = http.request(request) puts response.read_body ``` ```java import com.mashape.unirest.http.HttpResponse; import com.mashape.unirest.http.Unirest; HttpResponse response = Unirest.post("https://host.com/waves/v1/lightning-large/stream") .header("Authorization", "Bearer ") .header("Content-Type", "application/json") .body("{\n \"text\": \"string\",\n \"voice_id\": \"string\"\n}") .asString(); ``` ```php request('POST', 'https://host.com/waves/v1/lightning-large/stream', [ 'body' => '{ "text": "string", "voice_id": "string" }', 'headers' => [ 'Authorization' => 'Bearer ', 'Content-Type' => 'application/json', ], ]); echo $response->getBody(); ``` ```csharp using RestSharp; var client = new RestClient("https://host.com/waves/v1/lightning-large/stream"); var request = new RestRequest(Method.POST); request.AddHeader("Authorization", "Bearer "); request.AddHeader("Content-Type", "application/json"); request.AddParameter("application/json", "{\n \"text\": \"string\",\n \"voice_id\": \"string\"\n}", ParameterType.RequestBody); IRestResponse response = client.Execute(request); ``` ```swift import Foundation let headers = [ "Authorization": "Bearer ", "Content-Type": "application/json" ] let parameters = [ "text": "string", "voice_id": "string" ] as [String : Any] let postData = JSONSerialization.data(withJSONObject: parameters, options: []) let request = NSMutableURLRequest(url: NSURL(string: "https://host.com/waves/v1/lightning-large/stream")! as URL, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10.0) request.httpMethod = "POST" request.allHTTPHeaderFields = headers request.httpBody = postData as Data let session = URLSession.shared let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in if (error != nil) { print(error as Any) } else { let httpResponse = response as? HTTPURLResponse print(httpResponse) } }) dataTask.resume() ```