iPad Pro Apple Pencil Initial delay?

Discussion in 'iPad' started by fenjen, Nov 16, 2015.

  1. fenjen, Nov 16, 2015
    Last edited: Nov 16, 2015

    fenjen macrumors 6502


    Nov 9, 2012
    Hey guys,

    Im pretty excited for the Apple Pencil which I mostly want to use for writing down lecture notes. One thing I've noticed however is that, to me in some videos it seems like there's an initial delay between putting the pencil to the iPad and the actual line being rendered, longer than the delay when continuously tracking the pencil. Because for writing you obviously need to raise the pencil from the iPad a lot I'm worried it might not be the best tool for writing..

    As there are not that many good videos of the Apple pencil though I can't say for certain, so is there maybe anyone with a pencil or who has tried it in store who can comment on this? (There are currently no stores who have it in stock near where I live so I can't try for myself :( )
  2. supersalo macrumors 6502


    May 14, 2010
    From what I've read, the Notes app has virtually no lag or delay. Third party apps do have lag, but will need to be updated.
  3. supersalo macrumors 6502


    May 14, 2010
    I haven't used one in person yet (this is what I've read from comments of people that have used it)
  4. lewisd25 macrumors 6502a

    Jul 6, 2007
    Procreate has zero lag. Response time comes down to the developer's ability to properly implement Apple's pencil API.
  5. fenjen thread starter macrumors 6502


    Nov 9, 2012
    Well I'm not really talking about the normal lag that indeed has been discussed. To me it sometimes seems as if the iPad is waiting for something to render the line, after which the line suddenly pops in after which only the "normal lag" is still present.

    Most of the videos are just not clear enough though so I'm not really sure if I'm just seeing things.
  6. goomba478 macrumors regular

    May 10, 2012
    Fenjen, I played with one yesterday for about 15 minutes and I didn't experience any lag AT ALL in Notes. In the Photoshop sketch there may have been a slight, slight delay when shading or painting but it was still amazingly fast. I've heard Procreate is even better but it wasn't on the demo unit. It'll be a day one download for me. Trust me, this thing will be perfect for note taking, doodling, sketching, etc. Now if only we'd get them in stock!
  7. fenjen thread starter macrumors 6502


    Nov 9, 2012
    Haha that sounds great, thanks!
  8. Atomic Walrus macrumors 6502a

    Sep 24, 2012
    One of Apple's lag-reducing tricks involves predicting where the stroke is going. As far as I know there is no reliable way to predict when the user is about to initially make contact with the screen, and that might explain what you're seeing.

    I want to post some more general info about latency here because it seems like many are unfamiliar with the technical details behind it. A lot of people seem to think that every app will be as responsive as Notes and Procreate when they've been "updated," but this is not necessarily true. Plenty of x86 applications that've been around forever have laggy brush engines because the developers have never figured out how to and/or taken the time to resolve it.

    There are 3 sources of latency for pen input:
    -Hardware tracking lag is the latency introduced by the actual digtizer hardware and any interpolation that needs to be done on the raw data to get acceptable linearity. Does not vary between apps. Apple has clearly done a lot of work to bring this latency down. Some apps may not be taking complete advantage of this if they've not been rewritten to take advantage of the predictive technology, but I would expect that most apps with pressure sensitivity have already done this.

    -Brush lag. The brush engine may try to buffer a few frames of input to create a material simulation effect (some brush effects require this), it may buffer just to apply smoothing (bad design), or it may be too CPU-heavy and actually lag. Most of the difference between app performance is coming from here.

    -Display lag and vsync: Every display setup has its own latency added to the chain. On top of this, iOS does not allow an app developer to disable vsync. If you're not familiar with what vsync is, it's a way to avoid screen tearing (displaying a frame which consists of an old frame and part of a new frame because rendering is not synced to the monitor refresh rate). The problem with vsync is that, depending on the implementation, it can introduce a ton of lag. Triple buffered vsync will get you 50 ms of extra latency, usually more in my experience.

    Basically it's complicated. There's a huge low-hanging fruit there in allowing vsync to be disabled, but that doesn't sound like something Apple will be doing soon.
  9. tekchic macrumors 65816


    Apr 19, 2010
    Phoenix, AZ
    If you're looking at videos online, keep in mind that MANY of those are filmed at 240fps which is SLOW MOTION. I've heard of maybe a little lag in Adobe, but Notes and Procreate (Procreate is pretty much the gold standard for drawing on iPads) is excellent.

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8 November 16, 2015