Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch.embedded > #26626

Re: Sync to Android frame rate

Show all headers | View raw

On 5/18/2017 11:59 AM, John Speth wrote:
>> I'm looking for a way to synchronize some code activity to the Android
>> display frame rate. It's a short bit of code that will simply set the
>> color of a small display region, nothing more. Is there some sort of
>> method or hook that I can exploit for this purpose?
>
> I'll answer my own question, partially that is.  It appears one solution
> is to use the Choreographer class which provides a way to hook a
> callback function into the frame rate.  Below is the code.  It executes
> but the timing is sloppy.
>
> I can time the calls to doFrame() using System.nanoTime().  A little
> testing shows me the timing of calls to doFrame() is not uniform
> (ranging from 12 msec to 20 msec, expecting about 16 msec).  The
> callback argument is rock steady (about 16 msec) which makes me think
> it's a value that is computed at initialization time.
>
> It's a solution but it's not doing what I wanted because the callback is
> not timing precisely enough.  Still seeking advice, thank you.
>
> JJS
>
> ///////////////////////////////////////////////////////////////
>
> private FrameCallback frameCallback = null;
> private boolean frameCallbackPending = false;
>
> public void armVSyncHandler() {
>     if(!frameCallbackPending) {
>         frameCallbackPending = true;
>         if(frameCallback == null)
>         {
>             frameCallback = new FrameCallback() {
>                 @Override
>                 public void doFrame(long frameTimeNanos) {
>                     frameCallbackPending = false;
>
>                     // Do some work here
>
>                     armVSyncHandler();
>                 }
>             };
>         }
>         Choreographer.getInstance().postFrameCallback(frameCallback);
>     }
> }

Update: I ran this code on a newer and probably faster phone (Samsung 
Galaxy Grand Prime).  It seems to work like I wanted (no aliasing).  I 
conclude the original phone (ZTE X752C) was way short of compute capacity.

JJS

Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Sync to Android frame rate John Speth <johnspeth@yahoo.com> - 2017-05-17 17:23 -0700
  Re: Sync to Android frame rate John Speth <johnspeth@yahoo.com> - 2017-05-18 11:59 -0700
    Re: Sync to Android frame rate rickman <gnuarm@gmail.com> - 2017-05-18 21:53 -0400
      Re: Sync to Android frame rate Theo Markettos <theom+news@chiark.greenend.org.uk> - 2017-05-19 18:28 +0100
        Re: Sync to Android frame rate rickman <gnuarm@gmail.com> - 2017-05-19 13:47 -0400
        Re: Sync to Android frame rate John Speth <johnspeth@yahoo.com> - 2017-05-19 12:47 -0700
    Re: Sync to Android frame rate John Speth <johnspeth@yahoo.com> - 2017-05-19 12:51 -0700
      Re: Sync to Android frame rate Theo Markettos <theom+news@chiark.greenend.org.uk> - 2017-05-22 11:00 +0100
        Re: Sync to Android frame rate John Speth <johnspeth@yahoo.com> - 2017-05-22 09:24 -0700
          Re: Sync to Android frame rate Theo Markettos <theom+news@chiark.greenend.org.uk> - 2017-05-22 22:30 +0100

csiph-web