Xv and alignment requirements

Daniel Stone daniel at fooishbar.org
Thu May 30 15:31:01 PDT 2013


On 30 May 2013 18:26, Daniel Drake <dsd at laptop.org> wrote:
> However, we are finding that the gco2D_FilterBlit() call that makes
> this happen requires that each plane of the I420 image is aligned to a
> 512 byte boundary. And in these problematic videos, that requirement
> is not met (it is obviously resolution dependent), so the function
> returns an error and no video is shown.
> Any suggestions for how to deal with such a requirement at the DDX level?
> Is there some way that drivers can offer I420 Xv support but only if
> its neatly aligned? What would DDX developers with more experience
> than me do here?

No bigs - pretty much all hardware has this requirement! The
QueryImageAttributes Xv hook lets you specify what the pitch has to be
for each plane, so just round up from the width and set it there.
Clients do (and have to) respect that.


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