Video Quality and Window Managers (or lack thereof)

We have an application where there are problems with the video quality, specifically
vertical edges show jagged edges or tearing when there is horizontal motion. This is a ptz
security system, so this is quite noticeable to the customer.

Currently the system runs with just Xorg running, the application creates a framework and
renders video into it using xvimagesink.

While investigating I reflashed the unit to the factory image and ran the application with the
ubuntu unity desktop running, and the quality was much better. Reverting back to no window manager
and the problem came back.

The Xorg command lines are the same, the Xorg log files are nearly identical.

The application is exactly the same.

Any ideas why running with the unity desktop running would result in smoother video?

Thanks in Advance


We don’t have experience in unity desktop. Please other users can share experience.

Unity is the default window manager, and I can’t say I know a lot about it, but I can think of a number of things which might (i.e., “conjecture”) be involved. Unity start-up might be calling different options (the startup scripts, not Unity itself…or…environment variables rather than directly passed arguments). When in Unity you might explore the output from “xdpyinfo” (purely X11) and “glxinfo” (for GL accelerated apps).

Perhaps double buffering occurs when running Unity. Perhaps anti-aliasing is run with Unity.