At this point you can’t throw a rock without hitting a 4K, HDR-enabled television, at least if you’re throwing rocks in an electronics store. Why are you doing that? Cut it out, you’re gonna break something. Anyway, if your TV has both 4K resolution and HDR capability, now you can use HBO Max to the fullest on your Chromecast.
HBO made the announcement with version 18.104.22.168 of its Android app, rolling out now. That brings the resolution and dynamic range up for Android phones, TVs, and set-top boxes that support it. “Select titles” will also support Dolby Atmos.
This is all in preparation for HBO Max’s very first bit of 4K content, the much-hyped streaming release of Wonder Woman 1984 on Christmas day. At the time of writing none of the service’s extensive catalog is available in 4K, but the new Warner Bros. movies in 2021 will all land in higher resolution, along with “even more 4K UHD titles.” Hopefully that will include some of the old HBO series, too.
The new upgrade applies to the new Chromecast with Google TV (AKA a reskinned version of Android TV), the older Chromecast Ultra, NVIDIA’s various SHIELDs, and at least some of the TVs that manufacturers have pre-loaded with the Android TV operating system (mostly Sony). It may take a day or two for the update to propagate widely.