Regarding the three experiments I mentioned my previous post:
1. Turning off compositing did not solve the problem.
2. I did not try this, as the posts I read on other forums referring to these two xorg.conf options used them to fix other problems with the Catalyst driver, not this specific problem, so I decided not to bother.
3. This worked for me. The received video in Skype was perfect. The downside is that I had to have four media players open and paused, which is not exactly convenient. A worse downside was that, when I maximised a browser window during the Skype call, my laptop spontaneously rebooted (my guess is that X Windows crashed).
I solved the problem (in my case, at least): I installed media-video/guvcview and that fixed the received video in Skype. These are the steps I followed:
1. I launched Skype and made a video call. The received video image had little red dots and purple/green/blue tinting in the bottom half of the image.
2. I Installed guvcview using the package manager.
3. I launched guvcview in a Konsole (terminal) window. After guvcview created its configuration file /home/fitzcarraldo/.config/guvcview/video0 and checked various video and audio settings it exited because my Webcam was being used by Skype (‘libv4l2: error setting pixformat: Device or resource busy‘).
4. I clicked on the Webcam icon in the Skype video call window, to turn my Webcam off.
5. I launched guvcview again. The lower half of the received video image in Skype changed from little red spots to a continuous green-coloured band, and the upper half of the image now looked reasonable but still had some red- or blue-tinged patches.
6. On the Image Controls tab in the GUVCViewer Controls window I changed the video frequency from 60 Hz to 50 Hz then back to 60 Hz again. (I was just tinkering, and I believe this had no bearing on the outcome.)
7. I clicked on the ‘Quit’ button in the guvcview window to terminate the application.
8. I clicked on the Webcam icon in the Skype call window to turn the Webcam back on, and the received Skype video image changed to a perfect image.
I checked twice by rebooting and making a video call, and the received video image in Skype remained perfect after both reboots.
So it looks like the guvcview tool can be used to fix the problem. I've documented this in more detail with some screen snapshots in my blog post: Fixing a problem with received video in Skype when using the AMD Catalyst (FGLRX) driver in Linux
By the way, heindsight
, on another of my laptops I use the open-source Radeon driver instead of the closed-source Catalyst (FGLRX) driver, and the received video image in Skype is perfect on that laptop, so I believe you are right in thinking the problem only occurs if using the closed-source driver.