Fwd: Re: memory:DMABuf usage with waylandsink

[Damian Hobson-Garcia]

Hi Nicolas,

> CC: ssaito at igel.co.jp <ssaito at igel.co.jp>
> 
> Le lundi 04 septembre 2017 à 17:28 +0900, Damian Hobson-Garcia a
> écrit :
>> Hello All,
>>
>> I am working on a plugin for H/W that can output video buffers as
>> dmabufs for display on a wayland compositor via waylandsink.
>> It looks like the colour formats supported by the compositor are
>> reported by waylandsink in 2 separate caps structures, one for SHM
>> buffers and one for DMABUFs. The DMABUF structure sets the
>> GST_CAPS_FEATURE_MEMORY_DMABUF caps feature while the SHM one doesn't.
>>
>> According to the gstdmabuf.h header (plugins-base), though, this should
>> only be set for non-mappable DMABUF, but since my DMABUFs *are*
>> mappable, it seems like I shouldn't be setting this flag.  Without it,
>> though only the formats supported for SHM buffers can be negotiated.  Of
>> course, its easy enough to just lie and set the flag, but I'm wondering
>> if there is a more correct solution.
>>
>> In general, what should upstream plugins be doing to negotiate the
>> DMABUF formats with waylandsink?  I've tried to find some examples in
>> other plugins, but grep hasn't given me much to go on.
> 
> There is no solution to this problem other then using a caps feature.
> This of course prevents software element like text overlay or other in-
> place filter to work, you'll need a converter.

Ok, I see. Thank you for the feedback.

Damian