Optical audio output limitations

Discussion in 'Mac mini' started by BigMa, Oct 9, 2013.

  1. BigMa macrumors member

    Joined:
    May 31, 2012
    #1
    I understand optical out is restricted to 24 bit / 96 kHz PCM. :apple:
    ► Could somebody please explain if it is hardware or software related limitation? :confused:
    ► Is there any way to play 24 bit / 192 kHz PCM without using external DAC (something like Vox will probably downsample from 192 to 96...)? :confused:
     
  2. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #2
    [[ I understand optical out is restricted to 24 bit / 96 kHz PCM.
    ► Could somebody please explain if it is hardware or software related limitation? ]]

    I'm going to take a GUESS (and it's ONLY "a guess") that this is a hardware-based limitation and if you want "higher" output, you're going to have to "go around" the audio-out port. (That is, use the firewire port, the USB ports, etc.)

    If that's wrong, I'm sure others will jump in with a correction.
     
  3. jwhazel macrumors regular

    Joined:
    Sep 22, 2005
    #3
    It's a hardware limitation of the sound card. You'd have to use a USB Dac to get around this. Before you do that, here's some pretty sound scientific advise regarding 192/24: http://xiph.org/~xiphmont/demo/neil-young.html
     
  4. BigMa thread starter macrumors member

    Joined:
    May 31, 2012
    #4
    192/24 vs. 96/24 music

    Thank you for the great reference, jwhazel! :)

    I understand the Nyquist sampling theorem (96 kHz sampling frquency should be plenty enough for faithful music reproduction), and yet we often see "Audiophile 192/24" offerings (https://www.hdtracks.com/index.php?file=catalogdetail&valbum_code=HX603497920273). :confused:

    Perhaps there is something to it in the end… Maybe some musicians (by definition, people with highly trained discrimination abilities) could chime in with their impressions of 192/24 vs. 96/24 music? ;)
     
  5. Knara macrumors member

    Joined:
    Feb 12, 2010
    #5
    I am only an amateur recording guy, but I'll take a stab for you:

    Buried in that reference is the real reason why music *producers* use (in general) larger ranges for sampling than are needed for listening: Headroom and margins of error.

    Basically, if you are meticulous, you still only really need 96/16 to get a good recording. BUT, with the expanded ranges you have a lot more room to avoid mistakes from things like not properly calibrating your "0 point" and end up clipping due to the input from an instrument or mic, or due to using some production plugin that might cause the signal to clip after processing.

    So, more of a "production" thing than a "listener" thing. It's the same sort of philosophy as to why studio monitor speakers sound different than the speakers you would hook up to a sound system for home theater playback. With the studio monitors (and really usually you'll have a variety of them you can A-B with) you want as little "coloring" or "optimization" as possible. You want to hear it "flat". Now, some audiophiles may also like that sound, but the overwhelming majority of people would consider that sort of playback to sound "boring", so you have speaker systems that cater to "theater sound" and what not.

    But as for actual sound quality and accuracy, as the article points out, we're already covering the entire range of human hearing with the existing standard encoding, so anything more is lost due to biology.
     
  6. BigMa thread starter macrumors member

    Joined:
    May 31, 2012
    #6
    192/24 closer to the original live music

    Thank you Knara! :)

    Here we go: “BUT, with the expanded ranges you have a lot more room to avoid mistakes…” Maybe this is the reason 192/24 recordings are being offered? BUT, do they SOUND closer to the original live music than 96/24? :confused:

    Any musicians on the forum to chime in with their impressions of 192/24 vs. 96/24 music? ;)
     
  7. blanka macrumors 68000

    Joined:
    Jul 30, 2012
    #7
    This man will explain why 44.1/16bit delivers exactly the same:
    http://xiph.org/video/vid2.shtml

    I do however have a Phonic Firefly, Firewire interface that offers 192/24.

    You see, the biggest problem with CD's that sound crap is not the 44/16 thingy, but just that they are horrendous recordings.
     
  8. chabig macrumors 68040

    Joined:
    Sep 6, 2002
    #8
    Don't be confused. The human ear does not have the fidelity to hear any difference.
     
  9. Knara macrumors member

    Joined:
    Feb 12, 2010
    #9
    No, because the expanded range is only really perceivable by the computer during the production process.

    Make no mistake, 44/16 recordings cover the entire range of human hearing. There is nothing "left out" that makes one bit of difference to your ear.

    The linked article uses light as an analogous example: think of looking at a light bulb. Now, from science class, you know that in addition to the light that you perceive with your eyes, there are also wavelengths that are much longer (infrared on down) and much shorter (ultraviolet on up) than your eye can perceive.

    If I take a picture of that light bulb and then give it to you, does that picture reproduce the infrared and ultraviolet light? No. Can you tell with the sensor organs available to you as a human that they are missing? Absolutely not.

    ----------

    Yeah. There's some recordings from before the most recent "Remastering" craze (which really, insofar as I can tell, is just people running old recordings through compressors that are far too "strong") on CD that sound amazing.

    I actually go through used CD stores to find the original transfers from analog to CD, since it was before people started complaining that recordings were "too quiet".

    Sometimes makes life hard for my iTunes normalization setting, tho :D
     
  10. fredr500 macrumors regular

    Joined:
    Apr 12, 2007
    #10
    Experience speaking here.

    Before you spend a lot of money on high-end audio gear, get your hearing tested.

    My hearing is basically flat from 20hz to about 6Khz, then drops off a cliff. Good enough that I don't need hearing aids (then why can't I hear my wife?), but getting expensive gear to that is pretty flat 20-20,000hz was a waste of money for me. Doesn't mean my friends don't enjoy it, but me, nope.
     
  11. BigMa thread starter macrumors member

    Joined:
    May 31, 2012
    #11
    Thank you all very kindly: you put my mind at easy and I am a happy camper now! My wallet is very happy too! :)
     

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