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Topic: Auto-compensate signal delays

I have a project file from a customer who is having problems when he enables the "Auto-compensate signal delays" check-box in the File > Properties box.

When the check-box is enabled this is the result for Node 1, DSP - B:
DSP - B
DSP USAGE - 34.76%
MEMORY USAGE, BLOCK 0 - 105.31%
MEMORY USAGE, BLOCK 1 -   57.49%

When the check-box is not enabled this is the result for Node 1, DSP - B:
DSP - B
DSP USAGE - 82%
MEMORY USAGE, BLOCK 0 - 98%
MEMORY USAGE, BLOCK 1 -  83%

I was looking at the "details" of exactly what is assigned to each chip on the "Report" page and there are a TON of the compensating delays assigned to this chip when they are enabled. Of course when the delays are disabled, there is a pile of other stuff that is dropped in there instead.

So, finally to my question...

How is it possible for the compiler to stick all this stuff on that chip if it knows it won't fit? Can it not put these delays someplace else? I can not select them and move them anywhere. I can share the file if anyone wants to look at it.

-Josh

Josh Millward
Burnt Orange Studios

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Re: Auto-compensate signal delays

I understand there is some method to auto-compensate the signal propagation delay through sections of a project file.

Does anyone have any idea how to actually DO this?

I understand that it is possible, I just don't know how to do it.

-Josh

Josh Millward
Burnt Orange Studios

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Re: Auto-compensate signal delays

Josh,

FYI, I asked the same question in the documentation area but no responses as of yet!

http://peaveyoxford.com/forum/viewtopic.php?id=95

Actually, each new thread I've posted so far has done unanswered.  Am I being boycotted?  ...just kidding.

Thanks,

Joe

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Re: Auto-compensate signal delays

Hi Joe,
  No boycott, just busy trying to get you the right answers! 

  Here is some quick background.  When you turn on delay compensation, delay alignment devices are added in front of every output, and in from of every multi-input device that combines the inputs.  The compiler then places the devices on the DSP chips.  Finally, based on the placement, the compiler sets the alignment delay lengths to what ever is necessary to achieve the equal arrival time of signals.  Because this is done after the devices are placed, it is possible that when these delays are set the DSP memory will be over allocated.

  Here are things to try when this happens:

First, try and reduce the delay comp average size (in File/Properties.../Advanced...)  This is set to 6 by default and is probably too high.  Try and reduce this, even 0 is a valid setting.  This number provides a hint to the compiler about how much memory it should reserve for compensating for delays.

Second, reduce the processing vector length (in File/Properties...).  Reducing this uses less memory, potentially reduces the entire system delay, but consumes more DSP.  If your compile results show failure because of not enough memory but you have spare DSP cycles this has a good chance of working.

Last, you can try and hard assign some devices to DSP chips.  This might work if it is very close to working.

Regarding choosing which paths to compensate, there has been an experimental/unsupported way to do this.  I will investigate this and document what we find.  Has anyone tried this?

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Re: Auto-compensate signal delays

I time align signals currently through hard assigning devices and using XDABs creatively which works fine, it would be nice to have a shortcut though.

Thanks for the answers

Thanks,

Joe