Hi,
Summary: When playing H265 movies which are not explicitly 10-bit encoded, the colourspace appears to be reduced; colours are washed out, with blacks appearing noticably grey.
System:Vero 4K
Release: OSMC (Kodi 17.6) April 25 2018
Add-ons: iPlayer; YouTube; Keymap editor; FTP; Veracrypt
Detail:
Tonight I noticed that various H265 encoded movies appeared visibly washed out; black backgrounds are appearing as grey (although the letterboxing area displays the black level correctly). The issue doesn’t affect all files; my investigations, detailed below, lead me to believe it is restricted to 8-bit H265 movies only (oddly enough no TV shows I tested show the problem).
X264 files:
I checked a large number of X264 movies, and found that all play correctly (with black backgrounds being as dark as the TV and monitor allow).
H265 TV Shows:
I also tested at least 50 TV shows encoded in H265 from a wide varitey of sources, and found no problems with any of them, which I hadn’t expected (in fact I thought the opposite would be the case).
H265 10-bit Movies:
All H265 movie files which explicitly include ‘10bit’ in the filename work correctly.
Unfortunately I cannot determine if an H265 file is encoded in 8 or 10 bits from the information available via OSMC itself.
H265 Movie Testing (8 and 10 bit files):
I selected 21 H265 movies at random. 6 played with correct black levels, whilst 15 exhibit the problem; I tested these 15 on a Raspberry Pi 3, which was able to play them all perfectly (using software decoding); the other 6 would play audio only, which I believe confirms them to be 8-bit (as no 10bit H265 files will play on that hardware).
System version and updates:
I installed the April update on the Vero 4k a few days ago; whilst I definitely did not notice the colour problem prior to the update, I can’t say whether it is the cause of the issue, as I’ve not had the unit many weeks, and only this evening noticed a problem when playing various H265 movies (but not all).
I had previously modified the ‘attr’ file located in:
/sys/class/amhdmitx/amhdmitx0/
- adding ‘444, 10bit’ (minus the quotes), despite not having HDR capable displays. Removing this entry makes no difference.
I tried setting the ‘Force RGB output’ option to on, however this just causes the display to output garish greens and oranges.
I also tried switching the automatic HDR detection mode on, but again this made no difference.
Regarding add-ons, I have the iPlayer, YoutTube, and keymap editor.
I have also installed the Raspbian build of Veracrypt.
Earlier today I enabled FTP via ‘My OSMC’, but disabling this made no difference (as expected).
Display Hardware:
I’ve tested the Vero 4K on a cheap 22" ‘e-motion’ branded full 1080p TV, and a 27" Acer S271HL 1080p PC monitor, both connected via HDMI. The results are identical on both systems. Changing contrast and brightness levels only does not allievate the issue (the relative grey / black levels change in sync).
Other related information:
For what it’s worth, I noticed a very similar problem on my PC with an Nvidia GTX 570 gpu; in that case a setting in the driver allowed the entire colourspace to be utilised, which fixed the problem (however in this case all files, in all formats, were affected).
Conclusion:
Hopefully somebody can enlighten me on how to resolve this issue; I purchased the Vero 4K after several years of using Raspberry Pi’s (models 1,2,3) for Kodi / OSMC, specifically as files are increasingly using H265, which is not natively handled by the Pi’s Broadcom IV video hardware.
Many thanks in advance