Not getting dolby digital - only pro logic - help please!

Discussion in 'Apple TV and Home Theater' started by pprior, Jul 4, 2008.

  1. pprior macrumors 65816

    Aug 1, 2007
    I have a ATV with updated software. It is outputting via HDMI to a RadianceXD scaler which is then sending coax digital signal to a Lexicon MC1 processor.

    The lexicon front panel states what signal it's getting, and I'm getting nothing other than prologic.

    I've enabled dolby digital in the ATV menu.

    I -think- the problem is my handbrake encoding perhaps. If I command-I a movie within itunes under summary it says channels "stereo". When ripping in handbrake however I'm using "AVC/H.264Video/AAC + AC3 audio" which should be giving me AC3, right?

    I tried some HD trailers and didn't get digital there either, just DPL. Do apple's trailers play in AC3/5.1? If they do, then I've got a problem upstream from my ATV likely.

    Hopefully that's not too confusing - hope someone can help because although I'm happy with the video quality (especially with the radiance scaler!) not having digital sound bites!
  2. Cave Man macrumors 604

    Cave Man

    You can only passthrough AC3 once - you need your ATV connected directly to your Dolby Digital receiver. (Unless your equipment breaks the rules.)

    When you open it in Quicktime, does the Show Movie Properties (cmd-J) show that both AAC (analog up to DPLII) and AC-3 (Dolby Digital)?

    All Apple Trailers are encoded in AAC, not AC3.
  3. pprior thread starter macrumors 65816

    Aug 1, 2007
    Hey thanks for the reply -

    I wasn't aware of that movie info field under quicktime.

    Some of my movies have AAC/Stereo only and some have AC3/Surround listed below that, but the ones that have AC3 have a BLANK checkbox under "enabled."

    What does that mean? Do I have to "enable" this in every movie after I rip it? that seems quite silly.

    Thanks again so much!
  4. pprior thread starter macrumors 65816

    Aug 1, 2007
  5. Cave Man macrumors 604

    Cave Man

    No, leave it as is; that's exactly how it needs to be for the Apple TV. The Quicktime that runs your Apple TV is engineered to (1) check a movie file to see if an AC3 track is there and (2) determine if there's a receiver/amp capable of decoding Dolby Digital. If both conditions are true, then the ATV Quicktime automatically passes the AC3 stream to your receiver. (The AAC track is still enabled, which is why you have to turn down the volume on a connected device that uses analog.)
  6. Cave Man macrumors 604

    Cave Man

    I don't know those details (I don't have such a setup), but others who've had this problem solved it by going directly to the receiver from their ATVs, either by HDMI cable or optical cable.

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