Hi,
after finishing my ambilight project i spent a lot of time with calibration, raspberry images and driver test. I have a WS2801 stripe with poor weaker/stronger RGB channels so calibration is essential for me.
*** Logilink Fusicai USBTV007 Grabber ***
After many calibation tries without getting good results, especially for red and "skin" colors, i checked the image colors the grabber produces. I recognized that the grabber image is already very oversaturated as described here by @HalbesHaehnchen:
https://hyperion-project.org/t…ment.104/page-2#post-1687
So it would be pointless to try to correct this with hyperion calibration if the source image already lost color information. So i wanted to disable chroma with v4l2-ctl, but after trying different images, kernels, v4l-utils versions and last checking the driver source files: There is no implementation for any v4l2-ctl commands and i don't think there will be any in future, because the linux driver is a reverse-engineered windows driver. So i was stuck with the fushicai grabber. I can't imagine how anyone gets good colors with this chip?
*** mumbi stk1160 grabber ***
I use v4l2-ctl to set chroma_agc=0 at startup. Then with v4l grabber default stetting (2/8) i have decent, well saturated colors and with calibration everthing is much much better than with the fushicai, but: I get "frame too small" messages and blue ambilight flashes from time to time. I digged deeply into this issue, tried a lot of things and lately i found an issue directly regarding the driver implementation. But i'm unsure if there will be any fix for this...
*** Workaround for STK1160 flashes? ***
As far as i understand the code in libsrc/grabber/v4l2/V4L2Grabber.cpp, if the "Frame too small" occurs the frame will be skipped? Is that the reason for the blue flashes? My idea for a workaround solution: Can we save the last valid frame und use it if the next frame is corrupt? I think it nearly won't be noticeable? And much better than blue flashes?
I'm not familiar with C++ but i would greatly appreciate if the developers can check my idea and tell if its complete nonsence...
Issue reference on Github: https://github.com/hyperion-project/hyperion/issues/719