Encoding settings for Apple TV (Gen 2 & 3)

[andboom]

Whilst I'm aware that within Quicktime Pro it is easy to export a file for AppleTV, I am curious exactly what codecs and specific settings are a) playable and b) optimum for the highest picture & audio quality on both a second and third generation Apple TV respectively. As a professional video editor I'd like to be able to manually control my encoding settings to ensure that I am pushing the hardware of these AppleTVs to their maximum to deliver the highest bitrate and quality available. I am also curious, if I encode a clip as 1080P for a generation 3 AppleTV, will the same clip be playable on a generation 2 AppleTV, albeit at downrezzed 720P, or will the AppleTV require a separate 720P encoded version to work? Also, what forms of surround sound are supported by AppleTV? Thanks for any help.

[ipsychedelic]

I think you'll find this an interesting read.

[Pyromonkey83]

Originally Posted by andboom

Whilst I'm aware that within Quicktime Pro it is easy to export a file for AppleTV, I am curious exactly what codecs and specific settings are a) playable and b) optimum for the highest picture & audio quality on both a second and third generation Apple TV respectively. As a professional video editor I'd like to be able to manually control my encoding settings to ensure that I am pushing the hardware of these AppleTVs to their maximum to deliver the highest bitrate and quality available. I am also curious, if I encode a clip as 1080P for a generation 3 AppleTV, will the same clip be playable on a generation 2 AppleTV, albeit at downrezzed 720P, or will the AppleTV require a separate 720P encoded version to work? Also, what forms of surround sound are supported by AppleTV? Thanks for any help.

Ill try to answer your questions one by one as best I can.

Settings playable are the same as the High @ 4.0 h.264 profile settings. This is outlined as:

Max resolution: 1920x1080 @ 30 FPS
Max Bitrate: 25,000 kbps

The optimal settings I have found are:

Resolution: 1920x1080 @ 23.396 FPS
Bitrate: 19,000 kbps video / 640kbps AC3 Audio

More than that seems to cause some slight lag every once and a while and stuttering during high bitrate scenes. I recommend using a 2-pass VBR encode for this process (The CQ function in handbrake also works very well, but I like doing 2-pass as it helps keep files under a certain size).

The 2nd Gen Apple TV can also play these files, and iTunes will automatically downmix them to 720p, however higher bitrate files will require a high end processor to reduce stuttering.

The Apple TV itself supports AAC 2-channel files ONLY. If you do AAC 6-channel it will downmix it to a weird 3.0 audio as I learned from Dynaflash and verified with a file played on my surround sound system.

If you put a 6-channel AC3 file, the Apple TV can pass-through these files to your receiver and your receiver will decode properly if it supports AC3 decoding (most after 2005 or so will do this without a problem). To do this, you must set the audio settings in the Apple TV to support this.

You do this by going to Settings -> Audio and Video -> Dolby Digital -> ON (not auto).

I hope this answers your questions. Also keep in mind it is best to have 2 audio tracks, the primary being the 2-channel AAC, the secondary being the 6-channel AC3. This will allow universal support to all iPhones and iPads using the A4 processor and newer.