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POST
/
api
/
velma-2-stt-batch
Transcribe audio file with automatic language detection
curl --request POST \
  --url https://modulate-developer-apis.com/api/velma-2-stt-batch \
  --header 'Content-Type: multipart/form-data' \
  --header 'X-API-Key: <api-key>' \
  --form upload_file='@example-file' \
  --form speaker_diarization=true \
  --form emotion_signal=false \
  --form accent_signal=false \
  --form pii_phi_tagging=false
{
  "text": "Hello, how are you? Bonjour, ça va?",
  "duration_ms": 5000,
  "utterances": [
    {
      "utterance_uuid": "e5f6a7b8-c9d0-1234-efab-345678901234",
      "text": "Hello, how are you?",
      "start_ms": 0,
      "duration_ms": 2000,
      "speaker": 1,
      "language": "en",
      "emotion": "Neutral",
      "accent": "American"
    },
    {
      "utterance_uuid": "f6a7b8c9-d0e1-2345-fabc-456789012345",
      "text": "Bonjour, ça va?",
      "start_ms": 2500,
      "duration_ms": 2500,
      "speaker": 2,
      "language": "fr",
      "emotion": "Happy",
      "accent": "British"
    }
  ]
}

Documentation Index

Fetch the complete documentation index at: https://docs.modulate.ai/llms.txt

Use this file to discover all available pages before exploring further.

Authorizations

​
X-API-Key
string
header
required

API key for authentication. Your API key must be included in the X-API-Key header for all requests. API keys are tied to your organization and determine your access to models and usage limits.

Body

multipart/form-data
​
upload_file
file
required

Audio file to transcribe. Supported formats: AAC, AIFF, FLAC, MP3, MP4, MOV, OGG, Opus, WAV, WebM. Maximum file size: 100MB. Empty files are rejected.

Content-Type Requirement: The MIME type for this part SHOULD match the audio format being uploaded. Using application/octet-stream is strongly discouraged — the server uses the content type to select the correct audio decoder, and generic binary types may cause intermittent decoding failures or empty responses.

Correct MIME types by format:

  • AAC: audio/aac
  • AIFF: audio/aiff
  • FLAC: audio/flac
  • MP3: audio/mpeg
  • MP4: video/mp4
  • MOV: video/quicktime
  • OGG: audio/ogg
  • Opus: audio/opus
  • WAV: audio/wav
  • WebM: video/webm
​
speaker_diarization
boolean
default:true

Speaker diarization identifies different speakers in the audio. When enabled, each utterance includes a speaker identifier (e.g., 1, 2).

​
emotion_signal
boolean
default:false

Emotion detection for each utterance. When enabled, each utterance includes an emotion signal detected from the speaker's voice.

​
accent_signal
boolean
default:false

Accent detection for each utterance. When enabled, each utterance includes an accent signal detected from the speaker's voice.

​
pii_phi_tagging
boolean
default:false

PII/PHI tagging in utterance text. When enabled, personally identifiable information and personal health information are wrapped with appropriate tags in the transcription text.

Response

Transcription completed successfully

​
text
string
required

The complete transcribed text from the audio file, containing all utterances concatenated together. This provides a full transcript of the audio content.

Example:

"Hello everyone. Welcome to the meeting."

​
duration_ms
integer<int32>
required

The total duration of the processed audio in milliseconds. This value represents the actual audio duration and is used for usage tracking and billing purposes.

Required range: x >= 0
Example:

45000

​
utterances
object[]
required

Array of individual utterances detected in the audio, ordered by start time. Each utterance represents a continuous segment of speech, potentially from a specific speaker if diarization is enabled.