Speech-to-Text

This document explains how to use the IMKit SDK to convert voice message audio content into text.

Prerequisites

Ensure your SDK version is ≥ 5.22.0 and the speech-to-text feature is enabled in the RC Console.

tip

This feature is supported from version 5.22.0 onward and only applies to voice messages sent with SDK 5.22.0 or later. High-definition voice messages must meet these requirements: 8000Hz or 16000Hz sample rate, mono channel, aac format, and duration ≤ 60 seconds. Historical voice messages don't support this feature.

Demo

Overview

The IMKit SDK supports recording voice messages up to 60 seconds. In the chat UI, users can long-press a voice message bubble, select Convert to Text from the menu to invoke IMLib SDK's speech-to-text conversion. The SDK tracks visibility states of converted text, displaying text UI based on visibility settings when re-entering the conversation.

tip

The Convert to Text option won't appear if: the feature is disabled, message delivery failed, or conversion is in progress.

Component Diagram

Key Classes

Class	Purpose	Description
RCSTTContentView	STT content view	Displays conversion states.
RCSTTDetailView	Converted text view	Shows converted text.
RCSTTFailureView	Failure view	Displays conversion failure.
RCDotLoadingView	Loading view	Shows loading state during conversion.
RCSTTContentViewModel	Core STT class	Initiates requests, calculates text height, notifies RCSTTContentView to refresh.
RCSpeechToTextModel	STT data model	Tracks current conversion state.
RCSTTObserverContext	STT observer context	Handles all STT requests, registers/deregisters listeners.

Class diagram:

RCSpeechToTextModel is the data model used by IMKit SDK to track STT states. Key properties are listed below (see API docs for full details).

RCSpeechToTextModel properties:

Property	Type	Description
status	RCSpeechToTextStatus	Conversion status.
sttInfo	RCSpeechToTextInfo	Corresponds to database sttInfo.
isVisible	BOOL	Whether sttInfo view is visible (default: NO).

tip

• After initiating conversion, the default RCSpeechToTextInfo object in database has isVisible set to YES.

Workflow

RCSTTContentViewModel binds to RCSTTContentView via RCSTTContentViewModelDelegate. When RCSpeechToTextModel state changes, the ViewModel notifies RCSTTContentView to update UI.