"These Apple computers supply multichannel audio (up to 8 channels) and video signals over Mini DisplayPort:

• MacBook Pro (Retina, Mid 2012 and later) (1)
• Mac mini (Mid 2010 and later) (1)
• Mac Pro (Mid 2010 and Mid 2012)
• Mac Pro (Late 2013) (1)
• MacBook (Mid 2010 and later)
• MacBook Pro (Mid 2010 and later)
• MacBook Air (Late 2010 and later)
• iMac (Late 2009 and later)

(1) No additional adapter is necessary if you are connecting directly to the HDMI port on these specific models (above).

These Apple computers supply only video signals over Mini DisplayPort:

• iMac (Early 2009) and (Mid 2009)
• Mac Mini (Early 2009) and (Late 2009)
• MacBook (Late 2009)
• MacBook (13-inch Aluminum Late 2008)
• MacBook Pro (late 2008), (Mid 2009), and (Early 2009)
• MacBook Air (Late 2008) and (Mid 2009)
• Mac Pro (Early 2009)

To connect your television or other HDMI devices to your Mac, purchase a Mini DisplayPort to HDMI adapter..."

This Apple doc is also linked on the Audio/HT and Mac Basics/Tips pages. (As mentioned some years back, for 2009 Mac Pros, HDMI (and MDP I assume) audio was possible after applying Mac Pro 5,1 EFI (bootrom) using the unofficial updater originally from netkas IIRC.)
  

• How to identify MacBook Pro models
• Mac Basics Guide to Using OS X Mail
• OS X: How to migrate data from another Mac using Mountain Lion and earlier
• Error 3194, Error 17, or "This device isn't eligible for the requested build"
• What to do if OS X Installer says "OS X could not be installed on your computer" or "This disk cannot be used to start up your computer"
• Security and your Apple ID
• Identifying iPhone models
• iOS: Troubleshooting FaceTime and iMessage activation

(Topic-based page of Tips, Troubleshooting & How-To Guides for Mac/OS X/iOS Users.)
  

• Prosoft Releases Data Rescue 4
• Parallels Desktop 10 for Mac update 10.0.2 (summary)
• Superstar Designer Marc Newson is Joining Apple
• Intel's Core M Strategy: CPU Specs for 9mm Fanless Tablets & 2-in-1 Devices
• Broadcom Upgrades WiFi, Bluetooth Combo (EE times)
• QNAP TS-451 NAS Review (storagereview)
• XSLCmd Backdoor Now on OS X

Thursday Sept. 4th, 2014 News
• Apple posts info on Sept 9th event Live Stream
• OpenGL Extensions Viewer 4.2.7 update
• OWC Radio: Interview with Cinematographer/Producer Bobby Marko
• Sonnet Announces Dual-Port 10GBase-T Thunderbolt™ 2 Adapter
• "no updates" for Sims 4 Mac OS X version
• Pacifist 3.2.16 update (bugfix)
• Updated Apple Support/How-To/Troubleshooting Articles:
  - Installing or replacing memory in Late 2013 Mac Pro
  - Redeeming an iTunes Digital Copy
  - DVD or CD sharing Using Remote Disc
  - FAQ about Apple two-step verification
  - How to troubleshoot Wi-Fi connectivity
  - iOS: How to transfer or sync content to your computer
  - iOS: How to Use AirPlay to wirelessly stream content
  - Setting up iTunes and DVD Player for digital surround sound
  - Setting up Home Sharing for Apple TV (2nd and 3rd generation)
  - "You cannot install Mac OS X on this volume..." alert in Installer
  - How to verify authenticity of manually downloaded Apple Software Updates
  - About Apple video adapters and cables listing with compatible mac models
  - About the Mini DisplayPort to VGA adapter firmware update (FW update from 2009)
  - About LCD display pixel anomalies for Apple products released in 2010 & later
  - Mac notebooks: Using and maintaining your Apple MagSafe Adapter
  - Apple Portables: Troubleshooting MagSafe adapters

For links to older news pages, see the Archives.