Forum Discussion

dscully's avatar
dscully
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3 years ago
Solved

Incorrect Frame Buffer Stride Validation in VVP Frame Buffer

Hello, We believe we have discovered an issue with the VVP Frame Buffer component GUI validation for checking invalid values for Inter-buffer Stride in Quartus Pro 23.2. The documentation says the ...
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  • blakes_seven's avatar
    blakes_seven
    3 years ago

    David, thanks for spotting this bug, I understand it will be fixed in 23.4. Your solution looks correct.

ZH_Intel's avatar
ZH_Intel
Icon for Frequent Contributor rankFrequent Contributor
3 years ago

Hi David,


Apologize for the delayed respond.

I understand that this is not a bug.

Only active video frame is stored in frame buffer.

For example, when Htotal = 4400 Vtotal = 2250, only H-active = 3840 and Vactive = 2160 data is stored in frame buffer. The size of a frame in frame buffer is 3840x2160x byte of a pixel.


Thank you.

Best Regards,

Zul


dscully's avatar
dscully
Icon for New Contributor rankNew Contributor
3 years ago

Hi Zul,

"The size of a frame in frame buffer is 3840x2160x byte of a pixel". This is only correct when the inter-line stride is equal to the maximum bytes per line. In general, the size of a frame in frame buffer is max_height x Inter-line stride. Which can be greater than max_width x max_height x byte_of_pixel.

In practice, we were using these settings in our video pipeline and the last 56 lines of the frame appeared to be overwritten periodically. I've attached a screenshot showing this behavior.

The behavior disappeared when we changed the Inner-Line stride from 0x4000 (16384) to 0x3000 (12288).


If it is not a bug, can you explain the behavior?

Thanks,

David