Sorry for the long post…
So I’m starting to wonder if there are deeper issues going on with SDR/HDR mode switching in Channels. As I said earlier, I have my ATV set to 4K SDR 50Hz, and I have Channels colour mode switching set to Off. Out of curiosity, I set mode switching to On (video player, not app start) in Channels but made no changes to the ATV settings. Unexpectedly, when I tune to a channel, my TV goes black for a few seconds like it does when the ATV changes colour modes or frame rates, even though no changes should have been required. Any idea why it would do this?
I was testing partly because of this thread but also because I’ve been experiencing even more issues with Channels since tvOS 11.3 was released. In addition to the occasional jerky picture I’ve previously reported (Judder issue after skipping adverts?), I’ve also been getting random picture dropouts where in goes black for a split second. Again, only seeing this issue in Channels.
Now, a few things have updated recently: the tvOS 11.3 update, but also a firmware update to my TV (Sony KD-55XE9305) to finally enable Dolby Vision. Even though I’m only seeing issues in Channels, I thought I’d try replacing my HDMI cables to see if the problems resolve. I replaced them with ‘premium certified’ HDMI cables but saw no changes in behaviour.
That lead me to continue experimenting with ATV and Channels settings. I decided to change the ATV to output 4K Dolby Vision 50 Hz by default, and I changed Channels back to no mode switching (meaning Channels would be output in HDR/Dolby Vision). Surprisingly, no more judder and no more split-second picture dropouts! Any reason why that would be? Is it possible that with my original config (ATV SDR default, Channels mode switching off) Channels is still doing something to the video output that’s causing issues with my TV?
Even though the issues appear to be resolved if setting the ATV to HDR/DV by default, it’s not the ideal setup for me as I still find the ATV SDR—>HDR tone mapping to be not quite right. (It’s got much better but still not there for daily use in my opinion, not to mention the increased energy use when always running in HDR.)