5.1 AAC vs AC3

Discussion in 'Apple TV and Home Theater' started by refulgentis, Apr 11, 2008.

  1. refulgentis macrumors regular

    May 14, 2006
    Ideally, wouldn't movies use AAC instead of AC3 to compress multichannel audio? And can't an Apple TV output 5.1 AAC properly to a receiver?

    If so, why do people go to so much trouble to get AC3 into a MP4 container? is it because most receivers can only decode AC3? If this is true, then are there any receivers that can decode AAC into 5.1, and if the Apple TV can't decode AAC into 6 channels, will it just output it in stereo?
  2. zedsdead macrumors 68040

    Jun 20, 2007
    The problem is not outputting AAC 5.1 so much as the receivers not being able to decode AAC 5.1. Almost none do.

    The recent update allows AC-3 passthrough, and it works great.
  3. refulgentis thread starter macrumors regular

    May 14, 2006
    I understand...so does this mean the best way to "future-proof" my movies would be to convert AC3 to 5.1 AAC? Is this easy with the tools available now, or is it still a mess?

    Also, do you know specifically any receivers that can decode AAC, price not being an issue?
  4. mallbritton macrumors 6502a

    Nov 26, 2006
    No, the best way to "future proof" your movie files is to encode them with AC3+Dolby Pro Logic II (AAC). This will ensure your digital movie files will play on just about any device now and the immediate future.

  5. nutmac macrumors 68040

    Mar 30, 2004
    Many receivers, particularly newer models, support multi-channel PCM audio over HDMI. Ideally, Apple TV would convert multi-channel AAC into PCM, but alas, only 2-channel signal will be sent over HDMI.

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