> ## 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. # Which API should I use? > Modulate's model families, what each model returns, and how to choose between endpoints that overlap. Modulate's models are grouped into families by the kind of output they produce. Within a family, endpoints differ by language coverage, latency, and whether they take a file or a live stream. Each capability page below carries the full parameter, response, and audio format detail for its endpoints. ## Model families | Family | Model | Output | | - | - | - | | **Transcription** | [Multilingual Transcription](/get-started/stt) | A transcript with per-utterance timing, speaker labels, and optional emotion, accent, deepfake, and PII/PHI signals. Batch and streaming. | | | [English Fast Transcription](/get-started/stt) | An English transcript, with speaker turns when diarization is enabled. Batch and streaming. | | | [Multilingual Fast Transcription](/get-started/stt) | A transcript, its duration, and its language. No metadata. Batch and streaming, though only batch reports the language. | | **Detection** | [Deepfake Detection](/get-started/deepfake) | A `synthetic`, `non-synthetic`, or `no-content` verdict per frame, with confidence. Batch and streaming. | | | [Emotion Detection](/get-started/emotion) | A whole-file emotion label plus a per-window time series. Batch. | | | [Accent Detection](/get-started/accent) | A whole-file accent label plus a per-window time series. Batch. | | | [Music & Speech Detection](/get-started/music-detection) | Music and speech probabilities per 192 ms frame, plus clip totals. Batch and streaming. | | | [AI Music Detection](/get-started/ai-music-detection) | A clip verdict on AI-generated music, plus per-window vocal and instrumental scores. Batch and streaming. | | | [Language Detection](/get-started/language-detection) | The spoken language with a confidence score, across 100 languages. Batch. | | | [Audio Event Detection](/get-started/audio-event-detection) | A probability for each non-speech sound event detected, from a vocabulary of 42. Batch. | | **Redaction** | [PII/PHI Redaction](/get-started/pii) | A redacted transcript plus audio with the sensitive ranges silenced. Batch and streaming. | | **Triage** | [Velma Triage](/get-started/velma) | Behaviors, conversation type, participant roles, topics, sentiment, a summary, and a diarized transcript. Batch and streaming. | No Detection model returns a transcript. ## Endpoints that overlap ### Three models return a transcript Multilingual Transcription, PII/PHI Redaction, and Velma Triage all return a transcript. Pairing any of the last two with a transcription call returns the same text twice. | Requirement | Endpoint that covers it | | - | - | | A redacted transcript and audio with the sensitive ranges silenced | PII/PHI Redaction. A separate transcription call returns the same text. | | Behaviors, topics, and sentiment across a conversation | Velma Triage. The diarized transcript comes back as `clips`. | ### Four signals have two paths Each is available as a flag on Multilingual Transcription, attached per utterance, or as a dedicated endpoint that produces no transcript. English Fast and Multilingual Fast Transcription carry none of them. | Signal | Multilingual Transcription flag | Dedicated endpoint | What the dedicated endpoint adds | | - | - | - | - | | Deepfake | `deepfake_signal=true`, one score per utterance | Deepfake Detection | Frame-level verdicts, explicit `no-content` for silence, and verdicts on live audio without a transcript | | Emotion | `emotion_signal=true`, one label per utterance | Emotion Detection | A whole-file label and a per-window time series, without a transcript | | Accent | `accent_signal=true`, one label per utterance | Accent Detection | A whole-file label and a per-window time series, without a transcript | | PII/PHI | `pii_phi_tagging=true`, spans tagged in the transcript text | PII/PHI Redaction | Silenced audio, not only tagged text | ## Common scenarios | Goal | Endpoint | | - | - | | Recorded English calls, high volume | English Fast Transcription (batch). Bound parallel requests with a semaphore to stay inside the concurrency cap. | | Recorded calls in mixed or non-English languages, transcript only | Multilingual Fast Transcription (batch). Pass `language` when it is known. | | Live non-English captions, minimum latency | Multilingual Fast Transcription (streaming), for the 25 European languages it covers. The language is identified automatically and is not reported, so pair it with Language Detection if the code is needed. Outside those 25, use Multilingual Transcription (streaming). | | Captions, or search that seeks into the audio | English Fast Transcription (batch) with `time_stamps=true`. Returns a start time, end time, and alignment confidence per word, in seconds from the start of the file. | | Meeting transcription with speakers and emotion | Multilingual Transcription (batch) with `speaker_diarization=true` and `emotion_signal=true`. | | Live captions with speaker labels or non-English audio | Multilingual Transcription (streaming). | | Voice agent input, minimum latency | English Fast Transcription (streaming) with `endpointing=true`. Replace the displayed partial on each message rather than appending. | | Live English captions that attribute turns to speakers | English Fast Transcription (streaming) with `diarize=true` and `endpointing=true`. Check `speakers_capped` before trusting the labels past ten speakers. | | Screening a submitted clip for AI-generated voice | Deepfake Detection (batch). | | Anti-spoofing during a live voice-authentication flow | Deepfake Detection (streaming). Frame verdicts arrive during the call. | | A compliance recording that must be shareable | PII/PHI Redaction (batch). Returns the silenced MP3 and the tagged transcript together. | | Routing audio by spoken language | Language Detection (batch). Read `predicted_language_code`; low `confidence` means no commitment. | | Processing only speech from a live stream | Music & Speech Detection (streaming). Route on the frame classification. | | Screening uploaded tracks for AI-generated music | AI Music Detection (batch). The clip `primary_verdict` is more accurate than the per-window scores. | | Identifying non-speech sounds in a clip | Audio Event Detection (batch). Entries are independent probabilities, so threshold each event you care about; an absent key means not confidently detected, not absent from the audio. | | Fraud or compliance review on recorded calls | Velma Triage (batch) with a [detection package](/velma/detection-packages). | | Live monitoring for escalation or churn | Velma Triage (streaming). `behavior_detection` events arrive during the call. | ## Related * [Authentication and rate limits](/guides/authentication) * [Transcription signals](/get-started/stt#signals) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.