Origin coordinates of input buffer not updating when modifying frame size in sequence settings

Hi!

My question is certainly basic but I can't find a way to solve my problem and don't really understand the mechanism of input / output buffers.

I'm using the AE SDK to code a video effect plugin for Premiere Pro.

For each pixel in the output buffer, I'm trying to find the corresponding coordinates, after transformation, in the input buffer. To do that, I have to take into account that the user may choose to change the video frame size in the sequence settings. In that case, it introduces a positive or negative offset in the coordinate of the texture in the input buffer. I retrieve this information via the PF_LayeDef output->origin_x and output->origin_x variables (PF_InData in_data->output_origin_x and in_data->output_origin_y are always 0)

However I noticed that these informations are not updated when I change several times the frame size in the sequence settings. It is only updated when I close and restart Premiere.

I'd like to know where I can get this offset in real time? Or maybe I'm wrong in the process and I should do that an other way...

Thx in advance