Weird artifacts on TV-Out (radeon driver)
Since the "radeon" open-source driver got support for TV-Out, I get weird artifacts in the video overlay. It looks like parts of the image that should contain pure white (RGB 255 255 255) are replaced by some kind of white noise. I made an old school screenshot with my digital camera:
The center of both the explosion and the clouds should be white.
This happens only on the TV screen. On my Laptop's panel, everythink looks fine. Also, only the video overlay (both traditional an textured video) is affected.
Hardware is a Mobility Radeon 9700 with 32MB. I use the newest radeon driver from the git repository.
Okay, I have to correct some things I got wrong in my first posting.
1. It's not only the video overlay, normal windows are also affected.
2. It has nothing to do with "pure white" (RGB 255 255 255). Instead, 7 colors are affected. All of them have an R- and G-value of 255. The B-value ranges from 242 to 248. The noise intensity relates to this value. See my newest screenshot below:
3. The values above are valid for an X gamma of 1.0. Changing gamma via the "xgamma" tool changes the range of colors that are affected.
Looks all very mysterious to me. Please, can someone help?
I'll hazard a guess, here, though I may be completely wrong.
As I recall, TV's generally run conformant to the NTSC color standard (CCIR-601), which has a luminescence range from 16-235, rather than 0-255. My guess is the driver isn't clamping the output to those ranges, and the TV-out circuitry is delivering garbage, or an out of range signal which overloads your TV's circuit.
Can anyone with knowledge of the driver check on this?
I see this using my AGP 9500 too (at least the additional noise with white) with a S-video -> composite converter going to a composite input on the TV. I'm using 22.214.171.124 with the latest git driver using EXA+Textured Video in kmplayer. It does seem something like what TechMage89 says with more likely the input into the DAC being wrong. I'm guessing that my AGP card and a laptop's DAC can't both be outputting the wrong analog signal. I could be totally wrong there though, don't know enough about the driver or TV-out DACs.
Last edited by audi100quattro; 04-30-2008 at 09:42 AM.
I think Alex recently mentioned that there are still problems with S-video. Not sure if that was on specific cards or all, will ask.
This is a known problem. There's a bug filed on fdo bugzilla. I'm not exactly sure what the correct fix is unfortunately.
Thanks, but there hasn't been any activity on that bug for quite a while. Would you happen to know if there is someone still working on this? And is this only a problem with RV350 or are other cards also affected? Because it looks like only people with one of those are reporting this problem.
Originally Posted by agd5f
I don't have time to look at it further at the moment; I don't know if anyone else is. Is someone wanted to look into it I'd be happy to answer any questions, etc.
Originally Posted by bugmenot