AppleTV / Dolby Digital Problem

Discussion in 'Apple TV and Home Theater' started by eab6287, Aug 15, 2009.

  1. macrumors newbie

    Jul 2, 2007

    For some reason my ATV is not outputting Dolby digital signals during the playback of HD movies and trailers from the iTunes store. I've made sure the material has the Dolby logo, so it should be in dolby digital.

    I have the ATV connected to an onkyo receiver via HDMI and I know there's no problem here since the opening scene (when you first plug in apple tv) plays in DTS surround (reciever displays "dts" indicator)

    Any ideas? I think the dolby digital used to work....
  2. thread starter macrumors newbie

    Jul 2, 2007
    I did make sure the Dolby digital out setting in the ATV setup menu is on btw
  3. macrumors regular

    Feb 3, 2007
    I assume your other content is working (music, podcasts, all the stuff that's in stereo)? If so I had the same problem about a month ago. I too have an Onkyo receiver although I'm going in via component and optical. I ended up having to restore and update the ATV and then started fresh. I haven't had an issue since.
  4. macrumors 604

    Cave Man

    Unless something's changed, none of the trailers have Dolby Digital AC3.

    What's an example movie having this problem?

    That can't be. The ATV does not support DTS.
  5. macrumors newbie

    Aug 16, 2009
    Well,I'm sorry I am not professional...Good luck....
  6. thread starter macrumors newbie

    Jul 2, 2007
    The HD versions of trailers have always played in AC3 for me until this problem started. Apple began packaging most HD content with AC3 after the latest firmware update.

    This issue is happening with every movie that claims to have AC3. I haven't yet found one which does work.

    As far as DTS, apple tv does support it and the startup video is encoded in DTS

    By "support" I mean only that it's capable of passing a DTS signal to an appropriately equipped receiver which can then do the decoding. Same as ac3. Maybe by "support" you mean that the content in the iTunes store is not DTS encoded, which I realize.
  7. macrumors 68020

    Mar 27, 2003
    I hate to argue the point but the intro movie for the atv is done in aac and ac3. Reverse engineering that very movie is how hb first got ac3 passthru working in mp4.

    Would love to see a screenshot of that intro movie in qt player showing the dts track. I wish you were right (DTS Passthru would be awesome) but I am afraid not on this one.
  8. macrumors 604

    Cave Man

    They are AAC, not AC3.

    The first audio track must be AAC and the second audio track must be AC3 to get Dolby Digital (5.1).

    No, the startup video (see attachment) has AAC as its first audio track and AC3 as its second audio track. You cannot sync or stream any file that has DTS audio because DTS cannot be put into an MP4 container, which is required by the Apple TV.

    No, I mean the Apple TV will reject any file that has a DTS audio track.

    Attached Files:

  9. thread starter macrumors newbie

    Jul 2, 2007
    While I believe what you guys are saying, that doesn't explain the fact that my receiver displays 'DTS' during the intro movie and the DTS logo lights up (just as if I were playing a bluray or something with a DTS soundtrack). If you really don't believe me I'll take a picture of it or something. Strange...

    As far as this AAC/AC3 discussion, I don't know what AAC is. All I know is that purportedly most HD movies that you can rent on ATV are supposedly capable of playing in Dolby Digital (5.1 discrete channels). When playing one of these movies, my receiver (up until this week) displayed 'DD 5.1' (or DD EX 7.1 if I so chose), and now it doesn't; it can only be set to Pro Logic II.

    So far, I don't think anyone has explained why this is happening or how to fix it, but please correct me if I'm wrong.
  10. thread starter macrumors newbie

    Jul 2, 2007
    That can't be correct. Apple states on the AppleTV and iTunes websites that many HD titles come with Dolby Digital 5.1 surround. Therefore they must have an AC3 encoded track, right?.

    Further, this used to work. I've rented HD movies on ATV that DID have AC3 surround as indicated by the receiver's DD 5.1 display. When I rented an SD movie or an HD movie without the Dolby logo in its info page listing, the receiver just used Pro Logic II. Now it uses Pro Logic II even for movies which have the 'double d' logo that's supposed to indicate an AC3 track.

    The question is what would cause this to stop working and how might I fix it.
  11. macrumors 604

    Cave Man

    My Onkyo receiver illuminates the DD symbol with the startup video. Something about your receiver, I suspect, unless you've managed to disable DD out on your ATV.

    AAC is the 'analog' audio that is part of the MPEG-4 standard. All iTunes video and audio files use it.

    All of them have AAC audio as track 1. If they have digital audio they will have the double-D emblem denoting Dolby Digital (AC3) or explicitly state Dolby Digital 5.1.

    None of them come with 7.1, which would be Dolby Digital Plus (E-AC3). AAC is a two-channel matrix that can contain Dolby Pro Logic II (up to 5 channel surround). Since it was working for you before, there must be some setting issue on your receiver that has been changed.

    The purchased or rented TV shows and movies can have AC3 Dolby Digital (and all have AAC audio), but none of the trailers have AC3 (not even the HD trailers); they all have AAC audio tracks.

    I can't help you there (I assume you have Settings > Audio & Video > Dolby Digital enabled on your Apple TV). I haven't rented an HD movie from iTS since the early days of the 2.0 update, and I've never bought one. When I did rent Live Free Or Die Hard, it had AAC audio for track 1 and AC3 audio for track 2. All of my DVDs and Blu-rays have been transcoded for the Apple TV with AAC audio on track 1 and (when available) AC3 on track 2.
  12. thread starter macrumors newbie

    Jul 2, 2007
    I didn't disable DD out on the ATV as I've stated. There shouldn't be anything wrong with the receiver, since it works perfectly in every other scenario (Bluray, cable box, etc). Very weird...

    I realize obviously that they don't come with 7.1 discrete channels. However, if you have a receiver with DD EX processing, it creates the extra two channels for the rear using an algorithm. You can use DD EX processing on any AC3 material. DD Plus (and it's lossless sibling, DD TrueHD) are not the same thing as DD EX, and you're correct, they can contain 7.1 discrete channels.

    No setting on the receiver has been changed.

    Some of the HD trailers do have AC3 audio (or at least used to). I've played HD trailers in DD/AC3/whatever your preferred acronym is.

  13. thread starter macrumors newbie

    Jul 2, 2007
    Does anyone know how to solve this problem?

    This discussion has wandered a bunch....

    In short:

    I used to be able to play DD/AC3 5.1 soundtracks from some rented HD movies which have the 'double d' logo which indicates the presence of an AC3 track. The receiver would receive the AC3 signal and decode it, displaying 'DD 5.1'.

    This week out of nowhere, with no setting changed on the receiver or ATV and no connections changed, rented titles with the DD logo which the receiver SHOULD decode into 5.1 are no longer recognized as such. The receiver uses Pro Logic II crap decoding instead.

    If it helps, I have an Onkyo TX-SR606 and again, the signal (audio and video) are being transferred via HDMI to the receiver and then to the TV.
  14. macrumors 604

    Cave Man

    While I've not downloaded all of the Apple HD trailers, I have downloaded more than 50 and not one of them had an AC3 track. If you can point to one that does, I'll be convinced that some do. But until then, I'm skeptical.

    Now back to your problem. Have you transcoded any of your DVDs using Handbrake (0.9.3 or higher) with the Apple TV preset? If so, do these provide Dolby Digital to your receiver?
  15. macrumors 6502

    Dec 4, 2008
    I have an Onkyo 606 as well (ATV connected via HDMI), but have to agree with everyone else - the startup movie is definitely AC3 not DTS. If your receiver is showing DTS then you have the surround mode on one of the DTS equivalent Pro Logic modes, such as DTS:NEO 6 or DTS Express - the receiver lights up DTS when in these modes however these are obviously not 5.1 discrete surround.
    It should say on the front of the receiver which DTS mode it is in - if it is pure discrete 5.1 DTS, then that's all it will say.
    Are you sure you haven't accidently hit the Movie/TV button on the front of the receiver or on the remote, as this will cycle the surround modes for the channel input you are on.
    As Cave Man has mentioned, certain Movies & TV Shows are in AC3, but I've yet to see a trailer encoded with such a track.
  16. NOD
    macrumors member

    Jul 20, 2008
    I must agree w/ the above posters that DTS pass-through on :apple:TV is an impossibility unless you do a little hackage.

    As for QT trailers -- I actually could swear that I've seen a precious few that came up as 'Dolby Digital' rather than DPL on my rcvrs.

    I'll see if I can find some tomorrow.
  17. thread starter macrumors newbie

    Jul 2, 2007
    While I appreciate the discussion this question has spurred, I stilllll haven't been offered any solution to the problem. Anyone have any ideas? We seem to be talking about everything except the actual issue.

    Forgetting all this DTS/Trailers vs. Rentals/other misc. unrelated stuff...

    Why, when I watch a rented HD movie which does have AC3 encoding (as evidenced by the double d logo on the rental page), does my receiver no longer recognize this and therefore play the soundtrack in AC3/5.1 discrete?

    This used to work just as it should, and now it does not. I have tried resetting the receiver, ATV, etc. although I haven't done a full restore of the ATV.
  18. thread starter macrumors newbie

    Jul 2, 2007
    I haven't done this because I don't really have any reason to. For me, it's easier (and provides far superior video quality) to just stick discs in my Oppo Blu-Ray player, which upconverts DVDs to look as good as they possibly can. I've never really understood why it's worth the time and effort to rip DVDs. I guess it's more convenient to store them on a drive if you have a big library?

    If you think this would somehow be a good troubleshooting step I'm willing to try it.
  19. macrumors 604

    Cave Man

    If you use a DVD with Dolby Digital AC3 audio (which is virtually all of them) and use the Apple TV present in Handbrake, then you're guaranteed a movie file that will have both AAC (track 1) and AC3 (track 2) that is required by the Apple TV for Dolby Digital passthrough to your receiver. If that fails to work, then the problem likely lies with a receiver setting of some kind.
  20. macrumors 68020

    Mar 27, 2003
    I second Cave Man's reply. I have never seen an atv suddenly stop outputting a properly setup aac + ac3 soundtrack scenario.

    Fwiw, I too have an onkyo and would wager that somewhere along the way something was switched.

    As a test, try running toslink right from the atv to the onkyo and see what happens.
  21. macrumors member

    Feb 12, 2008
    iTunes Store - TV shows -Dolby Digital

    I would like just to add something:
    Definitely something changed the way TV shows are encoded on iTunes store.
    I bought LOST season 5 HD. Until episode 7 all the episodes presented Dolby Digital audio automatically recognized by my receiver( by the way is a Denon).
    After episode 8 and until the end of the show, bye bye Dolby Digital. The receiver automatically switches to Dolby Prologic.
    And guess what afterwards I bought Dexter season 3 (HD) and the same happened after episode 7!.
    I didn't had the the time to investigate the files but I'm pretty sure that something changed in the way the audio was encoded after all the receiver is the same and also the ATV SW version( and yes I didn't disabled DD audio output on my ATV).
  22. macrumors 68020

    Mar 27, 2003
    Well, there is one change in the 2.4 software itself that I know of regarding audio, you can now use *just* an ac3 track which had previously been broken by 2.3 ( not sure on the rev number to be honest ) 2.4 when i tested it will play a video with just an ac3 track again.

    Having said that, I don't know what that would have to do with any broken dd 5.1 output from existing encodes. Mine all still work fine.
  23. macrumors 6502

    Dec 4, 2008
    Did you check what I mentioned a few posts earlier? What does the front of the receiver say? DTS, DTS:Neo or DTS Express when either the ATV startup movie is playing or a known AC3 encoded movie?

    You must have something set-up wrong on the receiver. Have you cycled through the sound inputs? I would set the ATV input on your receiver to something that is not a surround mode (such as Stereo) then play a movie or TV show with an AC3 track to see if it auto-switches. This is how I have my receiver set-up so I get Stereo when listening to music, it auto-switches when I watch a movie, and then back again when finished.

    The other option, as per dynaflash's post, is to try a toslink to make sure it isn't hardware / cable

    As mentioned, I have a 606 and no problems with movies (rented or handbrake'd) or TV Shows that have an AC3 track over HDMI
  24. macrumors 6502a


    Mar 22, 2009
    I know it's a pain to go through, but you should restore your Apple TV to the factory defaults through the menu, then update to version 2.4 and re-link it to iTunes on your computer.
  25. macrumors newbie

    Sep 3, 2009

    I have to support the poster of this issue. I have a Pioneer Elite SC-07. I formerly had a Yamaha DSP A1; they are similar although the Pioneer supports more formats, HDMI, etc. I use it for EVERYTHING. I've had enough receivers to know the problem I'm experiencing w/ my new Apple TV is absolutely not a receiver setting. I have the same issue, I have it wired via HDMI Monster High Capacity cables, when the unit boots, i have it set as everything else (PS3, DirecTV, Elite Blue Ray player, etc. to auto-surround. Its not in NEO mode or any others, I have also tried PCM, Pure, Pure Direct, etc. for signaling. When I boot up, as I said, I get the Dolby Digital symbol AND it plays DD - sounds great. When I play the move or tv show previews, even the ones w/ DD, it goes immediately into Pro Logic II mode - it has never once gone to DD yet. It could be that they don't broadcast the 'previews' in DD - I have yet to rent a movie, but all is hooked up well, same hookup that works for every other device. Since I do get the broadcast during the plug in/start up, it is recognizing the DD as well when it's sent. It means to me that either a) Apple does not support Dolby Digital or b) They just don't use it for the previews but if I actually 'buy' or 'rent' the movie, it will be in DD. Any thoughts? (DD is enabled on my ATV)

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