V4L2: Is it possible implement video composite with V4L2?

[Bing Song]

Can you give more information on "Hans V. handle these cases"? Do you have any useful link for those?

How driver do sync? Suppose driver will sync V4L2 buffer time stamp with system time. V4L2 M2M device can copy time stamp from sink to source.

Is it possible to write one element based on video aggregator to do video composite based on V4L2?

Do you know any driver already implement this?

Regards,
Song Bing.

________________________________________
From: gstreamer-devel <gstreamer-devel-bounces at lists.freedesktop.org> on behalf of Nicolas Dufresne <nicolas.dufresne at collabora.com>
Sent: Monday, August 31, 2015 9:50 PM
To: Discussion of the development of and with GStreamer
Subject: Re: V4L2: Is it possible implement video composite with V4L2?

Le lundi 31 août 2015 à 09:59 +0000, Bing Song a écrit :
> Forget add subdev link:
> http://linuxtv.org/downloads/v4l-dvb-apis/subdev.html

Yes, this is at least how Hans V. handle these cases. If you are to use
GStreamer on top though with existing element (v4l2src/v4l2sink) you'd
have separate pipeline for sources, and sinks. A new element would have
to be written to actually make this compositor look like a single
element. That would only be required if your driver does not do any
synchronization.

Note though that if writing a driver is your goal, you should actually
post your questions to linux-media at vger.kernel.org . Even though we use
V4L2 in GStreamer, we are no expert in driver design, and subdev or
media controller architecture design.

Nicolas