My 4K HDR Sony Bravia (and the very cheap HDMI cables from Amazon!) supports all possible output formats for SDR and HDR10 (no Dolby Vision on my TV, though). So I played a bit with the settings. I have tvOS 11.2.5 beta. These are the main scenarios: ATV4K on HDR 50/60Hz 4:2:2 - Match Content disabled: There are no black screens when starting a video in either SDR or HDR. But the GUI colours are quite washed. I can "fix" it turning the Color up to 70 (default is 50) in the TV settings. It's quite far from my ideal. I didn't check the other options because I see no reason to enable the Match Content if I decide to have the GUI and apps in HDR. ATV4K on SDR 50/60Hz YCbCr 4:4:4 With Match Content: Range (for HDR): I can watch any SDR video without getting any black screen (caused by the TV changing settings). Obviously I get the temporary black screen with the delay when watching HDR content. I have the feeling the image isn't excellent (it's very slightly washed) With Match Content: Range & Frequency: As above but I get plenty of black screens while switching from an app to a video and vice-versa. ATV4K on SDR 50/60Hz RBG Low or High: The image seems better, but I think there is a bit of "crushed black". Especially with RGB Low (which should be the full RGB range if I understood correctly), although they look quite similar to me. The TV always switches when playing a video, no matter the frequency match. Personally I'd like to keep this last setting, but the TV switching can get annoying with time. Especially watching short video clips. I have actually opened a bug report with Apple, hoping something can be done to fix it. Otherwise, what would anyone suggest? Is it the "switching" from SDR to SDR in RGB mode an issue only with my Bravia or it generally happens with other 4K TVs as well?