v4l2src io-mode=4 and waylandsink rendering issue

[Nicolas Dufresne]

Le jeudi 02 août 2018 à 11:24 -0500, Matteo Valdina a écrit :
> Sure,
> I have an application that runs two GStreamer pipeline that looks
> something like that:
> Pipeline 1:
> v4l2src io-mode=4 device=/dev/video0 ! waylandsink
> Pipeline 2:
> v4l2src io-mode=4 device=/dev/video1 ! waylandsink
> 
> When both use DMAbuf (io-mode=4) the two waylandsink show both
> cameras. 
> To better describing:
> You see when both are running on the two waylandsink the same content
> from one of the camera and flicker between these two cameras.
> 
> I work around that forcing one of the camera in io-mode=2 (mmap). 

Looks like a bug in your compositor or camera driver to me. I have just
tested here on weston, no issue.

> 
> Best
> Matteo
> 
> On Thu, Aug 2, 2018 at 10:44 AM Nicolas Dufresne <
> nicolas at ndufresne.ca> wrote:
> > Le jeudi 02 août 2018 à 07:48 -0500, Matteo Valdina a écrit :
> > > Hi,
> > > I'm using two separate pipeline in the same process where the
> > input
> > > is a v4l2src and DMAbuf.
> > > The input feed is different but when I render with the
> > waylandsink
> > > the two pipelines content is mixed. Both display the same content
> > and
> > > flicker between the two contents.
> > 
> > This isn't very clear what you are doing. You should clarify.
> > 
> > > 
> > >  It looks like using DMA pool is shared across these two
> > pipelines.
> > > 
> > > I pass the wl_display and wl_surface to the waylandsink and I
> > also
> > > tried to pass two different wl_display but it doesn't make any
> > > difference.
> > > 
> > > Changing io-mode=4 (dmabuf) to something else (2 mmap) solved the
> > > issue.
> > > 
> > > Any suggestions?
> > 
> > Do you multi-plex the camera to multiple waylandsink element ?
> > 
> > > 
> > > Best
> > > Matteo Valdina
> > > -- 
> > > “There are two ways of constructing a software design: One way is
> > to
> > > make it so simple that there are obviously no deficiencies, and
> > the
> > > other way is to make it so complicated that there are no obvious
> > > deficiencies. The first method is far more difficult.”
> > > - Tony Hoare
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> 
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