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video rotation problem and VRFB

Karthik Ram
Prodigy 180 points

Hello,

In omap 3530 interfacing with ov5642 camera module i need to rotate the incoming video.

Here it is given two methods both in memory subsystem (virtual rotation frame buffer) and display subsystem (DMA).

 But it is given that VRFE is better than DMA.

In VRFE, i am confused  over virtual address space (0x7000 0000 - 0x7FFF FFFF, 0xE000 0000 - 0xFFFF FFFF) and physical address space (0x8000 0000 - 0xBFFF FFFF).

What is the purpose of virtual address space?

And one more question?

What will happen if i rotate the image 90 degrees. Will the image be cropped or the image get streched to the required screen size.

In spruf98g file it is not given clearly.

Please clarify my doubt.

 

With thanks and regards,

Karthik.

.

  • 0
    TI__Mastermind 43875 points

    Karthik,

    The VRFB method of rotation basically just creates a different view of the physical memory such that the scanning direction through the image is different for linear reading of the virtual address space. There are 4 virtual regions which each view the same physical memory but scan through in different schemes, yielding rotations of 0, 90, 180 and 270 degrees.

    The VRFB width is limited to 2048 pixels, so your application needs to understand that it is using a rotated frame buffer and hence that the line to line address delta is 2048 pixels.

    The different views of this memory allow you to put the image into the buffer in one orientation (say 0degrees) and read it out in a different orientation simply by accessing the image through a different memory window.

    BR,

    Steve