ANSI/SCTE 230 2021

Recommended Practice for Proper Handling of Audio-Video Synchronization in Cable Systems

Executive Summary

It has historically been a ‘given’ that television content is comprised of moving pictures and sound – and that the pictures and sound are presented in synchrony in the viewing / listening environment. Complex signal processing, distribution environments and consumer equipment have all conspired to make the synchronous presentation of pictures and the accompanying sound to a consumer a challenging task.

This document describes the nature of video and audio synchrony, how to recognize and measure the loss of synchrony, and potential identification and remediation steps when that synchrony is lost.


This Recommended Practice specifies proper procedures for the measurement of and maintenance of Audio-Video Synchronization (commonly known as “Lip Sync”) through various aspects of a cable system – including the headend and distribution architecture and devices.


This document assists the reader with recognition of the issue and where Lip Sync problems may have occurred and how to troubleshoot / mitigate those sync issues. Understanding the issues as outlined in this document will shorten the troubleshooting process and help to increase the ability of technical staff to communicate the issue to consumers as well as maintenance personnel.

Intended Audience

This document is intended for technical operations engineering and, potentially, customer contact personnel such as installers to be able to identify audio/video synchronization problems.