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Problem with Song Pos Ptr

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I'm trying to run a drum machine (Jamstix) as a software instrument and to work it requires Logic to pass it song position information.  It all works fine until there is a time signature change and then the plugin loses its place.  As far as I can tell the problem is with Logic because it seems to send the wrong song position pointer once it reaches a time signature change.  It's as if it is calculating song position based on the number of beats passed and the current time signature only.

To illustrate, the attached screen capture shows the effect.  I have inserted a plugin that displays the transport information that Logic sends to plugins and you can see that when the time signature changes the song position sent goes out of sync with Logic's own bar counter display.

Am I doing something wrong or is this a Logic bug?

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Looking a little deeper it seems that the transport info plugin I used is calculating song position from beats since the beginning and time signature - hence the error.


Jamstix's developer claims that the plugin reads SPP.  Is Logic sending that information to plugins?


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5 minutes ago, David Nahmani said:

Great, thanks a lot for letting us know what it was! 

As far as I can tell, and please correct we if I'm wrong, plugins don't seem to be given song position pointer, just beats from start and current time signature, and so the plugin has to calculate it for itself.  Since playback may not begin from the song start it looks as though the plugin has to be pre-programmed with a duplicate of the same time signature map that Logic is using.  There is no way for Logic to pass all of the required information to the plugin for any given arbitrary playback start point.

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