Lew Pitcher  wrote:
> Gareth's was W7 now W10 Downstairs Computer wrote:
>
> > One part of the GPU must be simply concerned with taking the frame
> > buffer and emitting it as a composite video stream, so I wonder how
> > the aspect ratio is set up?
>
> I'm not familiar with the internals of the VideoCore GPU, so I can't answer
> this question.

Display sizes are communicated to the GPU via the mailbox property
interface, or the mailbox framebuffer interface:

https://github.com/raspberrypi/firmware/wiki/Mailbox-framebuffer-interface
https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface

I'm not sure if the GPU-side registers for changing output video timing
(rather than just resolution) are exposed to the ARM.

Theo

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