Is 192Kbps AAC IN VIDEO playable on Apple TV 3?

Discussion in 'Apple TV and Home Theater' started by staknhalo, Feb 19, 2014.

  1. staknhalo macrumors newbie

    Joined:
    Feb 19, 2014
    #1
    Currently using Handbrake to convert my BR collection. I know iTunes default audio in HD video is 160Kbps AAC (not concerned about the 384Kbps AC3 track). Has anyone done a video encode with 192Kbps AAC or higher in video; and was it playable on the Apple TV 3? I searched, but couldn't find an answer. Thanks.
     
  2. dynaflash macrumors 68020

    Joined:
    Mar 27, 2003
    #2
    Yes, up to 320 is fine at the very least (maybe more).
     
  3. Idgit, Feb 21, 2014
    Last edited: Feb 21, 2014

    Idgit macrumors 6502

    Idgit

    Joined:
    Mar 14, 2004
    #3
    Why do the Handbrake Apple TV presets default to 160 Kbps AAC stereo tracks for encodes?
     
  4. Idgit macrumors 6502

    Idgit

    Joined:
    Mar 14, 2004
    #5
    Just curious. I'm no audiophile, but isn't 160 Kbps audio considered too low for good audio reproduction? The audio nerds of the Internets insist that stereo audio should be at least 256 AAC or 320 MP3 and anything less is going to sound like crap.
     
  5. jeff92k7 macrumors member

    Joined:
    Dec 14, 2012
    #6
    For full range music, yeah, higher bit rates will yield better results. However, most TV and movies are mainly spoken dialog or background sound effects. Lower bit rates are fine for acceptable sound quality. Unless you have reference monitors on your TV/Home theater, then you likely won't hear the difference between high bit rate audio and low bit rate audio even during the montage scenes while some overlaid song plays in the background.

    However, a lot of people on the "internets" like to listen with their eyes and if it isn't a big number, then they think it sounds like crap.

    If you want to do the math, a 384Kbps AC3 track yields only 64Kbps per channel (6 channels), so a 160Kbps AAC track at 80Kbps per channel (stereo) is still a higher bit rate. Of course, then you have to get into the argument about compression schemes and efficiency, and well, that just doesn't matter to the nerds of the internets who only look at the bigger numbers.
     
  6. Idgit macrumors 6502

    Idgit

    Joined:
    Mar 14, 2004
    #7
    That makes sense.

    I actually prefer the stereo AAC tracks over the AC3 tracks in some of my rips because the audio with AC3, especially the dialogue, can be so low for some reason. Strangely, I never encounter that problem with DTS tracks.
     
  7. westrock2000 macrumors 6502

    Joined:
    Oct 18, 2013
    #8
    384Kb/s was the standard for Laserdisc and DVD could go up to about 448Kb/s. However the AppleTV will support 640Kb/s which is the maximum of the AC3 (Dolby Digital) spec.

    Also I'm not sure if that is simply the "maximum" bitrate of the total stream that is allowed. In other words, you do not have to split it evenly amongst the channels, but when all summed together, you just have to stay with in that limit. So if you had a lot of sound in the center channel and subwoofer and very little out in the rear, you could vary the bitrate so that more goes to the center and LFE (like 192 or 256), while the rears drop down to 128 or 96. Again I do not know if this is true, but it would make sense to allow this.

    Handbrake also allows you to pack multiple streams into the M4V file. So for movies you generally want to have the "safe" AAC stereo stream first and then the AC3 stream second. The reason for this is so that the default sound track will play on everything, while you still have the good 5.1 for surround sound aware devices like AppleTV. And when playing on an iPad or iPhone with headphones, 160Kb/s is fine.

    But for movies that only have stereo tracks, I set the first track to 256Kb/s AAC.
     
  8. jeff92k7 macrumors member

    Joined:
    Dec 14, 2012
    #9
    Yeah...640 is the maximum for AC3 content, but the original post specifically mentioned the 384 number. I just went with that to avoid further confusion.

    I think that is actually correct. I'm not positive though. I'm not that familiar with the inner workings of the Dolby AC3 codec. That's why I made the comment about the efficiencies of the different compression formats. While I think that AC3 does work that way, and AAC does not (again, not positive), it's easier for most people to understand the simple math rather than get into a long, technical explanation that very quickly gets above most people's heads.

    That said...I wish the Apple TV would allow for DTS streams in content. I'd much rather have a 1.5Mb DTS stream than a 640kb AC3 stream. Of course, uncompressed audio would be better, but then the optical port would be useless.
     

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