I’ve only had my HDHomeRun Prime and CableCard for a few weeks, so I’m way behind the curve in terms of delivering cable to my house in that manner. I also ran into an issue a few weeks ago that I was reminded of this weekend as a Catalyst Control Suite and driver update reintroduced it to me – an annoying stroble-like flicker while watching certain channels in Media Center’s Live TV.
Depending on the channel and what’s actually on, it could be a constant flicker, or as I noticed, during scenes where there is a lot of brightness in the background, with a darker image in the foreground. Imagine someone being interviewed in front of a bright light source, like a window, or being outside in the sunlight. That would really set off the flicker.
What Ifound in my Googling, is that this is related to a 29/59 bug with Media Center and Live TV. I checked one of the channel sources causing me issues by entering the debug overlay (4 1 1 Info button sequence on your remote during Live TV playback) and went through the pages until I found the frame rate (image below was borrowed from Windows Experts as I couldn’t generate one over my RDP session).
I don’t really know why this would cause the flicker, however. I could understand the report of jerkiness and judder, but not this light-to-dark/dark-to-light strobe-effect flickering. So, I kept searching and came across something else – dynamic contrast. Dynamic contrast was a breakthrough in LCD technologies that allows a supporting image to dynamically change its contrast ratio according to what’s on the screen. For example, during a dark scene, the LCD backlight would be instructed to dim itself, yet proportionately amplify the transmission via the screen. This would keep the picture from appearing overexposed by any bright areas on an otherwise dark scene. The opposite pretty much occurs in brighter scenes, so they are not completely washed out by brightness.
Anyway, video cards have settings for dynamic contrast and I have an ATI Radeon HD5450 in my two primary HTPCs. I simply launched the Catalyst Control Center, located the Video section, and selected Quality. Right there it was – Enable dynamic contrast. I unchecked it.
I applied those settings, went back into Media Center, and fired up a channel in LiveTV that was giving me trouble – no more flickering! Just like that, instantly solved.
Now, for NVIDIA users, I’m not real sure if this is an issue or not, but I have seen where some users had it also. I do have an HTPC in the spare bedroom that has an NVIDIA GeForce 210 in it, but I haven’t tried any Live TV with that system other than to initially get it set up. I don’t know if it exhibits the flicker issue or not. I did dig through the settings looking for the dynamic contrast option though. I found it under Video > Adjust video color settings and I had to set the 2. How do you make color adjustments? to NVIDIA-controlled. If you then go to the Advanced tab, you’ll have a Dynamic contrast enhancement checkbox. If you leave the fore-mentioned setting to allow your video player control, it will be greyed out. I assume you can just uncheck this and save to get a similar result. Let me know if you have to do this and I’ll update this post.
Anyway, maybe it does, or does not have anything to do with the 29/59 bug, but at any rate, this fixed it for me. It’s not new news, but it is to me and having one more place out there to find the answer can’t hurt!