Apple has released its new Apple TV software update 4.2.1 that addresses flickering and other issues associated with the earlier update 4.2.

The latest update, which is a bug fix release and does not include any new features, comes only a couple of weeks after the initial 4.2 update.

Following table shows the issues addressed by the software update

Apple TV Software Update 4.2.1 features

FeatureSummary
TV compatibility Addresses issues that may cause the screen to flicker or display incorrect color on some older TVs.
Wake from sleep Addresses an issue where Apple TV may not wake up from sleep.
Audio Addresses an issue where audio may not be heard on some TV models after switching from another input.
Stability and performance Apple TV Software Update 4.2.1 includes stability and performance fixes for Apple TV.

Apple TV Software Update 4.2 features 

FeatureSummary
AirPlay for apps and websites Wirelessly stream video from iOS apps and websites that are enabled for AirPlay, on an iPhone, iPad, and iPod touch running iOS 4.3.
MLB.TV Watch live and on-demand Major League Baseball games in HD with an MLB.TV subscription. Pause, rewind, fast-forward, and switch between the home and away broadcast. Even non- subscribers can access real-time MLB scores and in-game stats, plus see the full-season schedule, standings, and stats. (Live games are subject to blackouts. See www.mlb.com/appletv for details.)
NBA Game Time Watch live and on-demand games with an NBA League Pass Broadband subscription. Pause, rewind, and fast-forward both live and on-demand games. And non-subscribers can access real-time NBA scores and in-game stats, plus see the full-season schedule, standings, stats, and video highlights. (Live and archived games are subject to blackouts. See www.nba.com/appletv for details.)
Netflix Dolby Digital 5.1 Enjoy Dolby Digital 5.1 surround sound when watching Netflix movies and TV shows on Apple TV. (Not available with all titles.)
New slideshow themes View photos with the new Scrapbook, Photo Mobile, and Holiday Mobile slideshow themes or use as the Apple TV screensaver.
Improved on-screen keyboard Search and enter names and passwords more easily with the redesigned on-screen keyboard.
AirPlay photo slideshow themes All Apple TV photo slideshow themes are now available when using AirPlay to wirelessly send a photo slideshow from an iPhone, iPad, or iPod touch to Apple TV.
HDMI color mode Apple TV Software Update 4.2 includes a setting for changing the color mode output over HDMI.
Connectivity and performance fixes Apple TV Software Update 4.2 includes performance and connectivity fixes for Apple TV.

 

Apple TV is Apple's digital media receiver designed to play IPTV digital content originating from the iTunes Store, Netflix, YouTube, Flickr, MobileMe or any Mac OS X or Windows computer running iTunes onto an enhanced-definition or high-definition widescreen television.

Apple offered a preview of the device in September 2006 and began shipping it the following March. But, Apple discontinued the earlier version of Apple TV.

In September 2010, Apple announced a second-generation version of the Apple TV. About a quarter of the size and one-third of the price of the original Apple TV, the new device can stream rented content from iTunes and video from computers or iOS devices via AirPlay.