DOP vs PCM

Discussion in 'Sound Science' started by endgame, Sep 16, 2017.
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DOP or PCM?

  1. DOP

    25.0%
  2. PCM

    75.0%
  1. endgame
    That's actually what I've been doing. I have several music apps that have options that let you select either DOP or PCM. So I'm listening to the exact same mastered track and just changing the way it's converted. I hear a difference in output, but again, I can't say one is better or worse.

    Just to clarify, I tend to agree that outputting in the same format to which it was encoded/mastered almost always sounds better. And in general, more conversions degrade the sound.
     
  2. endgame
    I erroneously thought this would be simpler to understand than it is. I thought it would be similar to watching a tv show in either 720P or 1080i and deciding which one you'd prefer. But sound seems to be more complicated than that. So I'm just gathering opinions to help me gain perspective.
     
  3. castleofargh Contributor
    720 vs 1080 on a screen can have 2 main reasons for a visual difference:
    1/ you're close enough to simply see the increase in resolution.
    2/ they're 2 different screens with a hundred reasons and components that could create a difference. leds of different models with different specs....

    in audio, most people under most circumstances won't have the ability to even tell 320mp3 from any highres format. so case 1/ pretty much doesn't exist when testing formats themselves. if there is a clear difference, you can start looking for what went wrong elsewhere. because something did go wrong.
    most digital formats do better than we can hear. nothing wrong with that, we can do it, we do it. but marketing keeps trying to sell audio based on resolution. so they keep pretending that it is what makes good sound when out of everything that makes the difference between crap music and brilliant sound, resolution has become irrelevant years ago.
    that's in part why audio seems more complicated. because we're being fed BS standards of quality all year long.

    about your experience, do you have a nice soundcard to record the sound coming out of the DAC? might not help tell why, but it could help tell if and how much difference there is. and how measurable it is :wink:
     
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  4. 71 dB
    I do not have a preference on this. IMO 16 bit / 44.1 kHz PCM is well enough for consumer audio when used optimally. IMO 24 bit / 96 kHz is overkill for consumer audio, waste of storage space. On studio things are different, more resolution gives necessary room to work. I believe the (real non-placebo) differences people hear (if they hear) between formats is due to ADCs and DACs operating differently with different formats (jitter etc.). A DAC optimized for 24 bit / 96 kHz is likely to give best results with that sample frequency. The benefit of lower sample rates is smaller file sizes and also that ADCs and DACs operate more accurately (they are electric circuits with non-zero time constants).

    If there is more to sound than just measurements, then measurements should be developed to address those issues too.
     
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  5. bigshot
    Are you matching the line level? What kind of difference are you hearing?
     
  6. pinnahertz
    No that's not what you're doing. There is no guarantee that there wasn't something significant done to the DoP that wasn't done to the PCM or vice versa. There are far more chances of mastering changes than any audible difference in the codecs.
    Level adjustment is the very first and most basic thing that mastering changes.
    The problem with this is just to edit DoP must be converted twice.
     
  7. TYATYA
    Off topic but a 5.1 DTS sounds far better than that of a 5.1Wav.
    Same for dts vs ac3
    Same as aac vs mp3....

    Belive or not to belive, up to you there's different sq achivement from those formats
     
  8. pinnahertz
    Where did you find DTS 5.1 and identically mastered 5.1 wav to compare?
    Same question for DTS and AAC.
     
  9. bigshot
    I'm assuming you're speaking of efficiency- one codec vs another at the same bitrate. Because if you up the bitrate of wav, ac3 and mp3, they can sound as good as the others. (except WAV which isn't a compression format.) Eventually the codec achieves transparency and everything sounds the same.
     
    Last edited: Sep 19, 2017
  10. gregorio
    Interesting statement which if true means that you personally have a preference for lower fidelity, as you think it "sounds far better".

    There are two problems for people who suggest there is more to sound than just measurements. Firstly, measurements can't be developed to address those issues because those who make that claim have no logical/rational suggestions of what it is that needs to be measured. If they have any suggestions at all, it's typically for something which is not a property of sound but a property of human perception. Secondly, if there is some property to sound itself which we don't know about and can't measure then it's irrelevant any way! Let's say there is something and we do develop a way to measure it, we'd then need a new type of recording technology because the ones we've got can only record and reproduce amplitude and frequency. Bit of a catch 22!

    G
     
  11. endgame
    So you're telling me that it's not possible for 2 headphones with near identical frequency response to sound very different?
     
  12. pinnahertz
    Funny, I don't recall reading those words, nor anything even close in meaning in gergorio's post. I would add that a full measurement profile of any transducer would include amplitude, frequency and time.

    Next it should be understood that measuring headphones in particular is difficult and prone to generating somewhat ambiguous data because, just looking at FR for now, position makes a huge difference, as does the specific artificial pinna and ear canal used in the measurement "head". Those things are based on averages of many humans, but that also means they are also a bit wrong for everyone. It's also really important to compare measurements of different headphones made by the same person with the same test setup. If you still have two "near identical" FR measurements, then we need to talk about what "near identical" is, and also look into the time domain and see what's going on past the initial arrival.

    It's all there, it's all measured, there's nothing wrong with the data other than the difficulty of making the measurements consistent in the first place. The problem is and has always been drawing direct correlation of incomplete measurements and (unbiased) perception. Once perception bias is eliminated, and measurements are complete and accurate, the correlation is good.
     
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  13. gregorio
    I didn't tell you that at all! In fact, it's entirely possible to play the same identical audio file twice, on exactly the same headphones/system and for them them to sound entirely different. You should read my posts more carefully before misrepresenting them!

    G
     
  14. gregorio
    I tend to state just amplitude and frequency and don't mention time explicitly because it's inclusion is already implicit in frequency. That's just me though.

    G
     
  15. pinnahertz
    Yes agreed. I included time in the data "cube" because a set of FR plots offset in time reveals resonances that time-blind FR misses.
     

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