Diarization

Diarization segments a recording by speaker. It answers “who spoke when”, not “what did they say”; pair it with transcription for both.

let result = try await RunAnywhere.diarization.diarize(AudioInput.file(path))

Options

Field	Meaning
`threshold`	How different two voices must be to count as separate speakers
`minimumDurationMs`	Ignore segments shorter than this
`mergeGapMs`	Join two segments from one speaker separated by less than this

mergeGapMs is the one to tune. Natural speech has pauses inside a turn, and without merging you get one speaker fragmented into a dozen segments.

Diarization inside transcription

For a transcript labelled by speaker rather than a separate segment list, ask the STT namespace instead:

let transcription = try await RunAnywhere.stt.transcribe(
    audio,
    options: SttOptions(diarization: true, maxSpeakers: 2)
)

Use the STT route when you want a readable transcript. Use the diarization namespace when you want timing, for example to drive a speaker timeline or to split a recording into per-speaker files.

Knowing the speaker count helps

maxSpeakers on the STT path, and a sensible threshold here, both improve accuracy a lot when you know how many people are in the room. Diarization over-segments when left to guess.

Streaming

Swift is the only SDK with a streaming diarizer:

let events = try await RunAnywhere.diarization.diarizeStream(
    audioStream,
    sampleRate: 16000,
    channels: 1,
    encoding: .pcmF32Le
)

for try await result in events {
    timeline.append(result)
}

Use it to label speakers live in a meeting view rather than after the recording ends.

Getting Started

Swift SDK

Kotlin SDK

React Native SDK

Flutter SDK

Web SDK

Electron SDK

Vibe Coding

Options

Diarization inside transcription

Knowing the speaker count helps

Streaming

​Options

​Diarization inside transcription

​Knowing the speaker count helps

​Streaming

Options

Diarization inside transcription

Knowing the speaker count helps

Streaming