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Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline

From Russell King - ARM Linux <linux@armlinux.org.uk>
Newsgroups linux.kernel
Subject Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline
Date 2017-03-17 13:30 +0100
Message-ID <tlZb4-6ms-11@gated-at.bofh.it> (permalink)
References (5 earlier) <tkxAd-ys-13@gated-at.bofh.it> <tkLDb-2Dk-9@gated-at.bofh.it> <tkPx8-5ja-19@gated-at.bofh.it> <tlYyl-5OT-7@gated-at.bofh.it> <tlYRH-6bS-9@gated-at.bofh.it>
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On Fri, Mar 17, 2017 at 01:02:07PM +0100, Philipp Zabel wrote:
> I think most of the simple, fixed pipeline use cases could be handled by
> libv4l2, by allowing to pass a v4l2 subdevice path to v4l2_open. If that
> function internally would set up the media links to the
> nearest /dev/video interface, propagate format, resolution and frame
> intervals if necessary, and return an fd to the video device, there'd be
> no additional complexity for the users beyond selecting the v4l2_subdev
> instead of the video device.

... which would then require gstreamer to be modified too. The gstreamer
v4l2 plugin looks for /dev/video* or /dev/v4l2/video* devices and monitors
these for changes, so gstreamer applications know which capture devices
are available:

  const gchar *paths[] = { "/dev", "/dev/v4l2", NULL };
  const gchar *names[] = { "video", NULL };

  /* Add some depedency, so the dynamic features get updated upon changes in
   * /dev/video* */
  gst_plugin_add_dependency (plugin,
      NULL, paths, names, GST_PLUGIN_DEPENDENCY_FLAG_FILE_NAME_IS_PREFIX);

I haven't checked yet whether sys/v4l2/gstv4l2deviceprovider.c knows
anything about the v4l2 subdevs.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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Thread

Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-14 04:50 +0100
  Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-14 09:00 +0100
    Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-14 11:30 +0100
      media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH v4  14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline) Pavel Machek <pavel@ucw.cz> - 2017-03-14 23:40 +0100
        Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH  v4 14/36] [media] v4l2-mc: add a function to inherit controls from a  pipeline) Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-15 02:00 +0100
          Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH         v4 14/36] [media] v4l2-mc: add a function to inherit controls from         a pipeline) Philippe De Muyter <phdm@macq.eu> - 2017-03-15 12:10 +0100
            Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH  v4 14/36] [media] v4l2-mc: add a function to inherit controls from a  pipeline) Nicolas Dufresne <nicolas@ndufresne.ca> - 2017-03-15 20:00 +0100
              Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH  v4 14/36] [media] v4l2-mc: add a function to inherit controls from a  pipeline) Philipp Zabel <p.zabel@pengutronix.de> - 2017-03-16 10:30 +0100
                Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH         v4 14/36] [media] v4l2-mc: add a function to inherit controls from         a pipeline) Philippe De Muyter <phdm@macq.eu> - 2017-03-16 11:00 +0100
                Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH  v4 14/36] [media] v4l2-mc: add a function to inherit controls from a  pipeline) Philipp Zabel <p.zabel@pengutronix.de> - 2017-03-16 11:10 +0100
                Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH         v4 14/36] [media] v4l2-mc: add a function to inherit controls from         a pipeline) Philippe De Muyter <phdm@macq.eu> - 2017-03-16 11:30 +0100
          Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH v4  14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline) Pavel Machek <pavel@ucw.cz> - 2017-03-15 19:10 +0100
            Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH  v4 14/36] [media] v4l2-mc: add a function to inherit controls from a  pipeline) Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-15 21:30 +0100
              Re: media / v4l2-mc: wishlist for complex cameras (was Re: [PATCH v4  14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline) Pavel Machek <pavel@ucw.cz> - 2017-03-16 23:20 +0100
      Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-20 14:30 +0100
        Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-20 16:50 +0100
          Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-20 17:20 +0100
            Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-20 18:40 +0100
    Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-17 12:50 +0100
      Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Sakari Ailus <sakari.ailus@linux.intel.com> - 2017-03-17 13:00 +0100
        Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Philipp Zabel <p.zabel@pengutronix.de> - 2017-03-17 15:00 +0100
          Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-17 15:50 +0100
            Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-20 14:20 +0100
              Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-20 16:20 +0100
        Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-17 15:10 +0100
          Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Pavel Machek <pavel@ucw.cz> - 2017-03-21 12:20 +0100
        Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-20 12:20 +0100
      Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Philipp Zabel <p.zabel@pengutronix.de> - 2017-03-17 13:10 +0100
        Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-17 13:30 +0100
          Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-17 19:00 +0100
      Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit  controls from a pipeline Pavel Machek <pavel@ucw.cz> - 2017-03-19 14:30 +0100
    Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2017-03-26 18:50 +0200

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