[Buildroot] [PATCH v2] package/gstreamer1/gst1-plugins-good: Select GUDEV if available
Ezequiel Garcia
ezequiel at vanguardiasur.com.ar
Sun Jun 7 20:07:34 UTC 2020
On Thu, 4 Jun 2020 at 18:23, Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
>
> Ezequiel, Nicolas, All,
>
> On 2020-06-01 13:43 -0300, Ezequiel Garcia spake thusly:
> > From: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> >
> > Using udev for probes (such as Video4Linux2 devices probes)
> > and device monitor greatly improves load time and monitoring performance.
> >
> > It also enables hotplug monitoring for cameras.
> >
> > Signed-off-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> > Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
> > ---
> > v2:
> > * Enable/disable v4l2-gudev explicitly
> >
> > package/gstreamer1/gst1-plugins-good/Config.in | 1 +
> > .../gstreamer1/gst1-plugins-good/gst1-plugins-good.mk | 9 +++++++++
> > 2 files changed, 10 insertions(+)
> >
> > diff --git a/package/gstreamer1/gst1-plugins-good/Config.in b/package/gstreamer1/gst1-plugins-good/Config.in
> > index 20aebc473e89..be77f5a82e3d 100644
> > --- a/package/gstreamer1/gst1-plugins-good/Config.in
> > +++ b/package/gstreamer1/gst1-plugins-good/Config.in
> > @@ -295,6 +295,7 @@ config BR2_PACKAGE_GST1_PLUGINS_GOOD_PLUGIN_SHOUT2
> > config BR2_PACKAGE_GST1_PLUGINS_GOOD_PLUGIN_V4L2
> > bool "v4l2"
> > depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_0 # multi planar api
> > + select BR2_PACKAGE_LIBGUDEV if BR2_PACKAGE_HAS_UDEV
>
> So there is still something that evades my understanding: gudev is
> selected only when V4L2 is enabled.
>
> However...
>
> > help
> > elements for Video 4 Linux
> >
> > diff --git a/package/gstreamer1/gst1-plugins-good/gst1-plugins-good.mk b/package/gstreamer1/gst1-plugins-good/gst1-plugins-good.mk
> > index 223af9850897..bd4bdcbc1ff1 100644
> > --- a/package/gstreamer1/gst1-plugins-good/gst1-plugins-good.mk
> > +++ b/package/gstreamer1/gst1-plugins-good/gst1-plugins-good.mk
> > @@ -40,6 +40,10 @@ else
> > GST1_PLUGINS_GOOD_CONF_OPTS += -Djack=disabled
> > endif
> >
> > +ifeq ($(BR2_PACKAGE_LIBGUDEV),y)
> > +GST1_PLUGINS_GOOD_DEPENDENCIES += libgudev
> > +endif
>
> The dependency is added glbally.
>
> So we end up with this truth table:
>
> gudev | v4l2 plugin | dependency
> --------+-------------+------------
> n | n | n
> Y | n | Y
> Y | Y | Y
>
> (the fourth case is not possible, as the v4l2 plugin select gudev)
>
> Is that what you expect?
>
> From the commit log, it looks like v4l2 is only one case amongst many:
> "Using udev for probes (such as Video4Linux2 devices probes)".
>
Yes, that was the idea, but this is a mistake on my side,
as I assumed gudev was being used by other plugins.
Seems Video4Linux2 plugins are really the only gudev users.
The REQUIREMENTS file in gst-plugins-good clarifies this:
Package: gudev
Version: >= 147
DebianPackage: libgudev-1.0-dev
Plugins: v4l2 (v4l2src)
URL: http://www.freedesktop.org/software/systemd/
Notes: This dependency is entirely optional, the video4linux plugin
will work just fine without it. gudev is only required for
the device probing and monitoring functionality to detect
video4linux devices appearing/disappearing at run-time.
Let me get a new patch.
Thanks again for the review,
Ezequiel
> So, I would have expected the select to be on the main
> gst1-plugins0-good symbol:
>
> menuconfig BR2_PACKAGE_GST1_PLUGINS_GOOD
> bool "gst1-plugins-good"
> select BR2_PACKAGE_LIBGUDEV if BR2_PACKAGE_HAS_UDEV
>
> Regards,
> Yann E. MORIN.
>
> > ifeq ($(BR2_PACKAGE_LIBV4L),y)
> > GST1_PLUGINS_GOOD_CONF_OPTS += -Dv4l2-libv4l2=enabled
> > GST1_PLUGINS_GOOD_DEPENDENCIES += libv4l
> > @@ -355,6 +359,11 @@ endif
> >
> > ifeq ($(BR2_PACKAGE_GST1_PLUGINS_GOOD_PLUGIN_V4L2),y)
> > GST1_PLUGINS_GOOD_CONF_OPTS += -Dv4l2=enabled
> > +ifeq ($(BR2_PACKAGE_LIBGUDEV),y)
> > +GST1_PLUGINS_GOOD_CONF_OPTS += -Dv4l2-gudev=enabled
> > +else
> > +GST1_PLUGINS_GOOD_CONF_OPTS += -Dv4l2-gudev=disabled
> > +endif
> > else
> > GST1_PLUGINS_GOOD_CONF_OPTS += -Dv4l2=disabled
> > endif
> > --
> > 2.26.0.rc2
> >
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