
Externally, the Apple TV 3 (1080p 3rd-Gen Apple TV) is virtually indistinguishable from the Apple TV 2nd generation. The real change again is that the Apple TV 3 now supports 1080p50 and 1080p60 over HDMI, where the previous Apple TV 2 only supported 720p50 and 720p60 at maximum over HDMI. The new Apple TV gives you access to HD movies and TV shows from iTunes and the entire Netflix streaming catalog. You can even play content from your iOS devices like iPad 3, iPhone 4S or iPod Touch on your TV using AirPlay.
The 1080p video playback really attracts most folks. But here’s your concern: will Apple TV 3 be able to support playing back 1080p H.264 MP4 movies with the AC3 5.1 (Dolby Digital) audio?
Most of you may have many Full HD 1080P MP4 movies ripped/converted from your Blu-ray discs with a Blu-ray Ripper for Apple TV 3 just for personal entertainment only. You may usually watch the movies on a 60″ HD TV through NAS streaming but not sure if Apple TV 3 will be able to play back the movies with AC3 5.1 if home sharing. From the specifications of the new Apple TV it just says “H.264 video up to 1080p, 30 frames per second, High or Main Profile level 4.0 or lower, Baseline profile level 3.0 or lower with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats”. So can the Apple TV 3 support AC3 5.1 audio?
The answer is Possible. According to my experience, the 2012 new Apple TV is not able to decode 5.1 surround sound to stereo by itself, if you want to play AC3 5.1 (Dolby Digital surround) audio you will need an AV receiver. Applet TV (including 2nd-gen and 3nd-gen) does not decode the surround audio itself, it will pass through the audio to AV receiver for decoding. If you do not have the AV receiver and connect Apple TV directly to your HD TV with HDMI, then there will be only video without sound while playing surround sound movie. But Apple TV itself just works ok with movie of stereo sound.

If you are looking for an app which makes it easy to either just watch or to convert Blu-ray movies to Apple TV 3 format at the original 1920×1080 resolution in an almost Apple-like way, and don’t mind spending $40 (they currently have a sale), I’ve had success using Pavtube’s Blu-ray to Apple TV Ripper for Mac to convert Blu-Ray discs to a format playable by Apple TV 3 and iTunes. I’ve found the quality to be excellent, and see no difference when compared to playing the discs themselves.

The steps: Ripping Blu-ray to Apple TV 3 videos with Dolby Digital 5.1 and 1080p HD quality
Step 1. Convert Blu-Ray using Pavtube Blu-ray Ripper to convert to 1080p H.264 *.mp4 (it has a preset “Apple TV” option to choose a format specific “Apple TV H.264 1920×1080(*.mp4)” to the new Apple TV).
PS: Here the profile doesn’t supply AC3 5.1 output, after several several conversions and tests I worked out the settings for converting Blu-ray to Apple TV 3 with Dolby Digital 5.1 (Select “H.264 HD Video(*.mov)” from “HD Video” category):
Video
Codec- H.264
Resolution- 1920×1080 (Full-HD)
Bitrate- 8000kbps
Framerate- 24fps
Audio
Codec- ac3
Sampling rate- 48khz
Bitrate- 128kbps
Channel- 5.1 Channels
Step 2. Import new .mp4 file into iTunes (drag .mp4 file to the iTunes icon on the dock)
On Apple TV, I browse the iTunes library for the movie and it plays the Blu-ray Rips 1080p movies smoothly and at full quality. I don’t think it could get much simpler unless of course, Apple provides native support for Blu-Ray which doesn’t seem likely.
Related posts:
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- 9 Best Ways to watch HD TV shows and Movies on your Apple iPad 3
- Enrich the movie entertainment on Amazon Kindle Fire through a “Blu-ray/DVD movie Transplant”
- Things You Gotta Known When Transferring Movies To PlayStation Vita

How do you set the Apple TV for 5.1 sound?
It should just work. Check that settings > Audio & Video >Dolby Digital hasn’t been turned off and make sure the movie you are watching actually has 5.1.