I definitely do not believe DV content is being converted to "fake" HDR10 via SDR.That was a question I had with regards to iTunes content, HDR, and the new ATV4K. If the movie indicates 4K and DV, there's no [implied] HDR10 encoding from the source, it's just 4K resolution + on-the-fly ATV4K HDR-like output (if your TV is HDR10 but not DV compatible)[?]
I share more the opinion of marvin_h here:
https://forums.macrumors.com/thread...elivering-4k-hdr.2073222/page-3#post-25153002
This solution (to have a HDR10 base layer and DV enhancement layer) is more logical, and incidentally seems to be the tech also UHD blurays in DV use.
If you look at the screenshots with media info on that thread, you can see that apple streams SDR and HDR versions of the same movie in different codecs.
So my guess is there are 2 versions (just like there were 3 versions so far: SD, 720p and 1080p) on their server and appropriate one is streamed depending on if your aTV requests a SDR or HDR rendering of the movie.
And yes, a DV HDR movie plays ok on my Bravia, that is HDR10 only. I mean equally well compared to other HDR10 movies I have. Can not compare to any Dolby Vision rendering, yet. According to Sony, DV support is due this year for very select list of models.