Re: Video overlay on sabresd

[Nikolay Dimitrov <picmaster@mail.bg>]

Hi Marco,

On 05/25/2015 04:22 PM, Marco Trillo wrote:
> Hi,
>
> On 05/25/2015 11:27 AM, Nikolay Dimitrov wrote:
>> Exactly. Regarding the MXCFB_SET_OVERLAY_POS - I was thinking this
>> ioctl is related to X/Y position of the layer and not about the layers'
>> Z-order (at least this is the impression I have looking at the mxcfb
>> driver and imx lib code). Please correct me if I'm wrong, but I thing
>> the Z-order of the BG/FG IPU layers is not programmable.
>
> Issuing the MXCFB_SET_GBL_ALPHA or MXCFB_SET_LOC_ALPHA ioctls() at
> /dev/fb0 should cause the `fb0' layer to display atop the `fb1' or video
> layer, mixed according to the global or per-pixel alpha value. This is
> what the docs say (which is a bit confusing):
>
> 3.2.2 DP global alpha combination
> To enable DP global alpha combination feature, we need to use fb ioctl
> MXCFB_SET_LOC_ALPHA [sic]. [...] By default, /dev/fb0 stands for the
> background frame buffer and /dev/fb2 stands for the foreground frame
> buffer [...] If the open file descriptor of /dev/fb0 is passed to this
> ioctl, the graphics plane of DP is set to the background plane,
> otherwise, the graphics plane is set to the foreground plane.
> (from Freescale's "Image Processing Unit V3 (IPUV3) Library User's Guide")
>
> After configuring the DP via these ioctls, you can then use the
> MXCFB_SET_CLR_KEY if you need to use color keying.

Well, my experiments are showing somewhat different behavior: setting
alpha on fb0 causes color key not to work on fb1. Alpha needs to be
explicitly set to the FG layer (fb1) in order color key to work.

Regards,
Nikolay