720p24hz Support and HDR Modes

Development Development & Testing
1

Hi,

just wondering if the Amlogic S912 kernel supports 720p @ 24hz resolution?

Also, when HDR autoswitching is supported, will it use logic similar to this???
HDR File <=30Hz play with 4:4:4 chroma at 10 bit
HDR File > 30Hz play with 4:2:0 chroma at 10 bit

or will it always use 4:2:0 chroma at 10 bit as that is generally how movies are encode?

Thanks in advance.

2

We are not using 420 or 422 chroma right now, at all. There are unresolved issues with those chroma settings.
I haven’t seen 720P HDR content.

3

Thanks for the update - was 2 different queries. Apologies as I should of made 2 topics.

The 720p/24hz query was more to do with the new whitelist. My AVR/TV supports this resolution and frame rate, but when I run a “cat /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap”

I only get the below resolutions, no 720p @ 24hz.

480p60hz
576p50hz
720p60hz
1080i60hz
1080p60hz
720p50hz
1080i50hz
1080p30hz
1080p50hz
1080p24hz
2160p30hz
2160p25hz
2160p24hz
smpte24hz
smpte50hz
smpte60hz
smpte50hz420
smpte60hz420
2160p50hz
2160p60hz
2160p50hz420
2160p60hz420

Thanks again.

4

That is typical, my HDR TV doesn’t list 720p@24Hz either.
The whitelist seems to prioritize refresh rate before resolution, so it will select a different resolution that supports 24Hz, and if no such option exists in the white list, it won’t switch at all. At least that was my experience, this whitelist thing is something the Kodi team implemented, not us.

5

As I know there is no 720p24Hz in HDMI specification.
That’s why there are no such resolutions available.

6

^^exactly.
If somehow you manage to send 720p/24 output, you’d probably get blank screen (no signal).

7

True, but both my TV and AVR support 720p/24hz according to the specs:
https://www.sony.com.au/electronics/support/res/manuals/4689/46893331M.pdf

8

It’s possible that they support it, but don’t expose it in the EDID.