opencv 3.2.0-1: imshow() very slow

[René Berber]

On 5/7/2017 10:31 AM, Falk Tannhäuser wrote:

> I started to test the new OpenCV packages and I noticed that each call
> to the imshow() function delays for usually 25 seconds. Most of the
> time, the following message is displayed:
> 
> ** (Great title:11352): WARNING **: Error retrieving accessibility bus
> address: org.freedesktop.DBus.Error.NoReply: Did not receive a reply.
> Possible causes include: the remote application did not send a reply,
> the message bus security policy blocked the reply, the reply timeout
> expired, or the network connection was broken.
> 
> More rarely, a different message, as for example the following one, is
> shown:
> 
> ** (Great title:9472): WARNING **: Error retrieving accessibility bus
> address: org.freedesktop.DBus.Error.TimedOut: Failed to activate service
> 'org.a11y.Bus': timed out
[snip]

Obviously you are not running dbus-daemon, which accounts for the
time-out, and the delay, but where does that dependency come from? Is it
needed? apparently not.

According to OpenCV's documentation
(http://docs.opencv.org/2.4/doc/tutorials/introduction/linux_install/linux_install.html)
there is no such dependency.

Check out the libraries linked, and probably one of them has that
dependency.  Dbus library is linked somehow, the problem is which other
library was the one that brought it.  Perhaps checking with pkg-config
to see which one uses it would help.

Of course there's a better hint on your message: 'org.a11y.Bus'  I have
no idea what library, or program uses that Dbus ID.  Using Google I
found
https://github.com/GNOME/at-spi2-core/blob/master/bus/org.a11y.Bus.service.in
which is Gnome... so perhaps the OpenCV released only works with Gnome &
X-Windows running.
--
R. Berber


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