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This guide shows you how to convert an audio file into text using Smallest AI’s Pulse STT model.

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Pre-Recorded Audio

Transcribe pre-recorded audio files using synchronous HTTPS POST requests. Perfect for batch processing, archived media, and offline transcription workflows.
The Pre-Recorded API allows you to upload audio files and receive complete transcripts in a single request. It can process an audio file uploaded as raw bytes or take a URL to retrieve one from a remote server.

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When to Use Pre-Recorded Transcription

  • Batch processing: Transcribe multiple audio files at once
  • Archived media: Process existing recordings, podcasts, or videos
  • Offline workflows: Upload files that are already stored locally or in cloud storage
  • Complete transcripts: When you need the full transcription before proceeding

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Endpoint

POST https://waves-api.smallest.ai/api/v1/pulse/get_text

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Authentication

Head over to the smallest console to generate an API key, if not done previously. Also look at Authentication guide for more information about API keys and their usage. Include your API key in the Authorization header: 
Authorization: Bearer SMALLEST_API_KEY

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Example Request

The API supports two input methods: Raw Audio Bytes and Audio URL. For details on both methods, see the Audio Specifications guide.

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Method 1: Raw Audio Bytes

Upload audio files directly by sending raw audio data: 
curl --request POST \
  --url "https://waves-api.smallest.ai/api/v1/pulse/get_text?model=pulse&language=en&word_timestamps=true" \
  --header "Authorization: Bearer $SMALLEST_API_KEY" \
  --header "Content-Type: audio/wav" \
  --data-binary "@/path/to/audio.wav"

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Method 2: Audio URL

Provide a URL to an audio file hosted remotely. This is useful when your audio files are stored in cloud storage (S3, Google Cloud Storage, etc.) or accessible via HTTP/HTTPS: 
curl --request POST \
  --url "https://waves-api.smallest.ai/api/v1/pulse/get_text?model=pulse&language=en&word_timestamps=true" \
  --header "Authorization: Bearer $SMALLEST_API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "url": "https://example.com/audio.mp3"
  }'

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Example Response

A successful request returns a JSON object with the transcription: 
{
  "status": "success",
  "transcription": "Hello, this is a test transcription.",
  "words": [
    {"start": 0.48, "end": 1.12, "word": "Hello,"},
    {"start": 1.12, "end": 1.28, "word": "this"},
    {"start": 1.28, "end": 1.44, "word": "is"},
    {"start": 1.44, "end": 2.16, "word": "a"},
    {"start": 2.16, "end": 2.96, "word": "test"},
    {"start": 2.96, "end": 3.76, "word": "transcription."}
  ],
  "utterances": [
    {"start": 0.48, "end": 3.76, "text": "Hello, this is a test transcription."}
  ]
}

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Next Steps