Cheese: choppy refresh

[Chris Gregan]

<Build: UNR 20080725>
<Environment: CG - 8.9">

Summary:
Web camera resolution can be lowered when being used in viewfinder mode then raised to full resolution for photos. It looks like this is not being done for web cameras connected to UNR.

Steps to Reproduce:
1) Select Graphics Category
2) Launch Cheese

Expected result:
When using camera as a viewfinder resolution is lowered so refresh rate is higher.

Actual result:
Camera is running at full resolution so refresh is slow

[Neil J. Patel (njpatel)]

It also seems to suffer from refrehs problems...maybe caused by the launcher's GL window behind it?

[Chih-Hsyuan Ho (chih)]

Neil, any idea how you will be dealing with this issue?

[Paul Larson (pwlars)]

Moving to Ubuntu distribution

[Filippo Argiolas (fargiolas)]

I don't believe the feature requested here will happen anytime soon. Photos are saved directly from the same stream of the viewfinder, a frame is taken and encoded into a jpeg file. To do what the OP suggested we will need to stop the pipeline, close the device, reopen it with an higher resolution, take a frame, stop the pipeline again and reopen it with the lower resolution.
It will take no less than 3-6 seconds just to shoot a photo. I'd say it's a wontfix.

About refresh issues I believe Neil is talking about some issue we had in the past with gtk double buffering, they should be fixed in git or in the 2.27.3 release expected in the next few days.

[Gary Lasker (gary-lasker)]

Filippo's comment #4 is an excellent description of the technical issues involved in trying to do a "real-time" webcam resolution switch when taking a photo. In fact, some test code I wrote a while back to do just this resulted in just over 5 seconds from the time the "Take a Photo" button was pressed to the point that the reduced-resolution "viewfinder" image was restored. Note that for the entire duration of the process no viewfinder image was available. The result was a completely unacceptable user experience.

The good news is that this problem can be easily worked around in current versions of Cheese by simply setting the default webcam resolution to a lower setting as desired via the Preferences dialog. This allows the user to make the tradeoff between optimal viewfinder performance and photo resolution.