AVS Device SDK Features

This page provides extra information to help you implement certain AVS features with the Alexa Voice Service (AVS) Device SDK. For code samples and full implementation details, see the AVS Device SDK on GitHub or the AVS Device SDK API references.


This page isn't an exhaustive list of all SDK features available.


The Alexa Voice Service (AVS) Device SDK 1.17 adds support for captions.

In the SDK, it's disabled by default. You enable through the CMake build option CAPTIONS=ON. You must also install a new dependency – the libwebvtt parsing library. Webvtt is a C/C++ library for interpreting and authoring WebVTT content. WebVTT is a caption and subtitle format designed for use with HTML5 audio and video elements.

By default, captions works with the en-US locale. If you want to support another locale, you must modify the line break logic in the CaptionManager::onParsed() method and use a locale-safe method for determining the break points between words. For example, you can use the ICU BreakIterator to handle the task. The exact method of this implementation is determined by you.