HDR to SDR conversion

Have looked through some older posts, but wondered if anyone has had success in playing 4K mkv files in a 1080 system. I have some files via latest functionality added to makemkv. Via the Vero 4k, playback is fine in terms of motion/resolution, but image is a bit bland. I think the colour is roughly ok, but everything is a bit dull, lacking in brightness/contrast. Here are a few parameter values in case that helps (kit downstream of the Vero is a Marantz NR1603 AVR and a Panasonic 1080 TV):

osmc@osmc:~$ cat /sys/class/amhdmitx/amhdmitx0/hdr_cap
Supported EOTF:
Traditional SDR: 0
Traditional HDR: 0
SMPTE ST 2084: 0
Future EOTF: 0
Supported SMD type1: 0
Luminance Data
Max: 0
Avg: 0
Min: 0

osmc@osmc:~$ cat /sys/class/amhdmitx/amhdmitx0/edid
Rx Brand Name: MJI
Rx Product Name: marantz-AVR
Manufacture Week: 0
Manufacture Year: 2012
Physcial size(cm): 0 x 0
EDID Verison: 1.3
EDID block number: 0x1
blk0 chksum: 0x90
Source Physical Address[a.b.c.d]: 2.5.0.0
native Mode 72, VIC (native 16):
ColorDeepSupport b8
31 16 20 5 32 19 4 18 3 17 2 22 7 21 6 1 14 35 15 36 29 37 30 38
Audio {format, channel, freq, cce}
{1, 7, 7f, 7}
{7, 5, 1e, 0}
{2, 5, 7, 0}
{11, 7, 7e, 1}
{10, 7, 6, 0}
{12, 7, 7e, 0}
Speaker Allocation: 5f
Vendor: 0xc03
MaxTMDSClock1 190 MHz
ColorMetry: 0x1f
SCDC: 0
RR_Cap: 0
LTE_340M_Scramble: 0
DeepColor
checkvalue: 0x90de0000

The Marantz is saying it’s receiving 8 bit colour, so conversion seems to be happening? Image is just a bit dull though compared to equivalent blu ray files.

Unfortunately there’s no specification on how this should this be done; so there’s not something we can precisely follow.

In the future we may have some presets that can be chosen via the GUI.

Sam