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.
Release: OSMC (Kodi 17.6) April 25 2018
Add-ons: iPlayer; YouTube; Keymap editor; FTP; Veracrypt
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).
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:
- 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).
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).
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