[VDPAU] ffmpeg and HEVC: Partial success, need help understanding problem

[Philip Langdale]

On Sat, 23 May 2015 11:32:13 -0700
Philip Langdale <philipl at overt.org> wrote:

> Although I've written what i think is correct reference handling code,
> until I get that NumLongTermPictureSliceHeaderBits thing sorted out, I
> don't think I can meaningfully test any of that.
> 
> So, I've been looking at an Intra-only sample, and I've actually got
> something to appear on the screen - yay.
> 
> I'm not sure how to describe what I'm seeing in technical terms,
> because I'm not familiar with all the HEVC jargon, but it shows the
> video essentially being rendered in two parts (are these slices?) with
> one part appearing to be rendered correctly, and the other rendered
> half-way down the frame, and then looping back around with the bottom
> part at the top.
> 
> Visually, this looks like part of the frame, roughly 'foreground
> elements' in the right place, and the background offset incorrectly.
> 
> Right now I can't comprehend what I've done wrong to achieve this -
> maybe incorrect scaling list transformations?

Ok, that's not right. I'd forgotten what the original sample looked
like. What I think it really looks like is that it's rendering twice as
tall as it should, alternating black lines with the actual picture
lines, and then that's wrapping around.

--phil