AssemblyAI
AssemblyAI Universal-3 Pro is a promptable speech-to-text model with language detection, formatting, speaker labels, and vocabulary guidance.
AssemblyAI documentation:
Model
| Model ID | Notes |
|---|---|
assemblyai/universal-3-pro | Universal-3 Pro cloud transcription model. OSTT sends this as speech_models = ["universal-3-pro"]. |
Params
toml
[assemblyai.universal-3-pro.params]
language_detection = true
format_text = true
speaker_labels = true
keyterms_prompt = ["OSTT", "Whisper", "Rust"]bash
ostt transcribe meeting.mp3 -m assemblyai/universal-3-pro --param speaker_labels=true --param keyterms_prompt=OSTT,Whisper
ostt model params assemblyai/universal-3-pro --format jsonDo not set prompt and keyterms_prompt together. AssemblyAI documents them as alternatives: use prompt for transcription style and behavior, and keyterms_prompt when you know the specific terms that should be recognized. OSTT validates this before sending a request.
| Param | Type | Description |
|---|---|---|
prompt | string | Natural-language instruction for transcription style, vocabulary, speaker roles, or domain context. AssemblyAI supports up to 1,500 words for Universal-3 Pro. |
keyterms_prompt | string list | Terms to bias recognition. AssemblyAI supports up to 1,000 words or phrases for Universal-3 Pro, with a maximum of 6 words per phrase. Saved ostt keyword terms are used as fallback only when keyterms_prompt and prompt are not set. |
language_code | string | Known source language code. |
language_detection | boolean | Detect language automatically. |
format_text | boolean | Apply punctuation, casing, and numeric formatting. |
punctuate | boolean | Add punctuation. |
disfluencies | boolean | Include filler words and false starts. |
filter_profanity | boolean | Mask profanity. |
speaker_labels | boolean | Enable speaker labels. |
speakers_expected | integer | Expected speaker count. |
speech_threshold | number | Threshold for speech detection. |
temperature | number | Sampling temperature, 0.0 to 1.0. |
word_boost | string list | Vocabulary boost terms. |
boost_param | string | Boost strength parameter. |