Black bande are grey

#1

Hi,

I don’t know why but now, the blacks bands during i’m watching à film are greys and not Black…

I’m alone why this issue ? How résolve it ?

Rgds
Akhlan

#2

First, we need logs to find out.

1 Like
#3

Some tvs have a setting similar to hdmi black level. Try changing that. My Samsung looked grey until i changed this

#4

I noticed this issue as well with rec709 1080p Bluray remuxes. I don’t have this issue with 4K BT.2020 remuxes. I can post logs tonight.

#5

Hi,

I have been able to reproduce this issue with some interesting findings.

First off, I’d like to mention again that I never had this issue with any 4K BT.2020 files, only on certain, if not all, BT.709 files with a wider than 16:9 aspect ratio. Note: I did play a 2.39:1 aspect ratio file where the black bars were black but upon inspection in MediaInfo, and verifying on my pc, the black bars are encoded into the file, i.e. 16:9 aspect ratio video file.

In Video settings, if I leave “Force RGB” off (default), my projector is set to YUV colourspace manually and everything looks OK except the black bars are grey when playing these certain files as mentioned.

After enabling “Force RGB” and rebooting, playing the same file, black bars still look grey when I set my projector to RGB 0-255 colourspace, but when I set my projector to RGB 16-235 the black bars now look black, but dark parts in the video now looks crushed with lost detail compared to RGB 0-255 setting on my projector. The 0-255 setting is definitely the correct one, because I realize in the other setting that it also makes colours look oversaturated, especially reds and skin tones.

At this point I’d like to make it clear that the “Use limited range 16-235” setting was never enabled, which confirms 0-255 is correct in RGB mode, so all is good, it’s just the black bars are not black but grey.

Now here’s the kicker, while fiddling around with these colourspace settings in RGB mode, I realized that the file playing back in the default YUV space where the grey bars are showing up, looks the same as when I played it back in RGB mode on the Vero 4K+ with the projector set to RGB 16-235. I.e. crushed blacks and oversaturated colours due to wrong RGB mode on the display.

So to me at this point this issue is bigger than just having grey black bars, the colour space is seemingly output incorrectly or something is going wrong where the display has to interpret this YUV signal.

Logs: https://paste.osmc.tv/oyuzenidiq
MediaInfo of offending file: https://paste.osmc.tv/dawiveyeve.rib

I hope this helps.

#6

Thanks for the feedback

Can you produce a sample of the file where the problem is noticeable?

Thanks

Sam

#7

Hi Sam

I’d like to backtrack a bit on what I said previously w.r.t. colours etc., it was an unscientific test. I redit it more scientifically tonight and although there are differences between YUV and RGB output, for now I will just say I was wrong about “… playing back in the default YUV space … looks the same as when I played it back in RGB mode on the Vero 4K+ with the projector set to RGB 16-235”.

For the problem described in this thread, I’ve found a sample file on the net that behaves exactly the same and causes gray bands, again, it’s a 2.4:1 widescreen file. The colours seemingly appear correct but above and below the file, as displayed in 1920x1080 16:9, there appears grey bands instead of black.

Here’s the file:
Christie Cinema Trailer Celebrating 85 Years (Scope)

#11

Can’t reproduce here. Can you try on another display as a test?

#12

The symptoms you describe suggest the files you are playing are full-range but wrongly tagged as limited range. You can try this on the commandline:

echo 1 | sudo tee /sys/module/am_vecm/parameters/range_control

Then make sure the output range from Vero (set in the GUI) is the same as what the display is expecting (ie both limited or both full-range). If that fixes the problem then you should consider re-encoding the files as limited range is the standard.

I can’t tell from the clip you posted whether the blacks are crushed. The letterbox bars are as black as they get on my TV.

#13

I have this problem with all videos that have original black bars (720p and 1080p not tested with 4K)

Since the last update, i haven’t this issue ans i don’t change TV :wink:

#14

Hi I figured it must have been more widespread if it was a real bug, so I did the following and it seems to have fixed it. Not sure what I could have done to misconfigure it. If I run into it again I will post here again.

1 Like
#15

It appears that my issue was the following setting which is wrong for my setup:

<setting id="videoscreen.limitedrangeaml">false</setting>

I’ve done a test and ran two scenarios, both in Force RGB off mode, so Kodi was always in YCbCr mode.

In the first scenario I enabled limited range in the GUI and played a widescreen file. Everything looked fine, and the black bars are nice and black.

In the second scenario I enabled full range in the GUI, now menus appeared lighter. When I played widescreen file the black bars are grey. This kind of makes sense because all YCbCr consumer content conforms to a spec that says it must be in limited range.

My projector only has one YUV mode (i.e. YCbCr setting, can’t specify 0-255 or 16-235 levels). What I didn’t know previously was that this limited range setting in Kodi not only affects when output is in RGB but also in YCbCr.

However, after scenario two above, I was intrigued. Why did the black bars appear grey, but the video content’s blacks still looked nice and black? I then did a test with the black levels test file as per Kodi wiki (https://kodi.wiki/view/Video_levels_and_color_space) and it appears black levels are the same in both scenarios.

So to me it seems Limited Range setting should be enabled in GUI, at least for my setup. But it seems also, in some if not all cases, this does not detrimentally affect consumer video, best case it only messes up black bars to look grey.

#16

no new about this issue ?

#17

We need more information from you

#18

Which information ?

#19

osmc debug logs and media info and or sample of the files that give you problems

#20

OSMC Debug Log can be find here : https://paste.osmc.tv/wiceyosuro

and media info of “X-Men - Dark Phoenix.mkv” but i reproduce for all 720p or 1080p file… No problem with 4K file

General
Unique ID : 107634964180951460548339803687349905448 (0x50F9BD746F7A9F31DBBEDBE6CE6BE828)
Complete name : /Volumes/Videos/Films HD/X-Men - Saga/X-Men - Dark Phoenix/X-Men - Dark Phoenix.mkv
Format : Matroska
Format version : Version 4 / Version 2
File size : 9.35 GiB
Duration : 1 h 53 min
Overall bit rate : 11.8 Mb/s
Encoded date : UTC 2019-09-07 16:48:45
Writing application : mkvmerge v29.0.0 (‘Like It Or Not’) 32-bit
Writing library : libebml v1.3.6 + libmatroska v1.4.9

Video
ID : 4
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings : CABAC / 5 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 5 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1 h 53 min
Bit rate : 9 479 kb/s
Width : 1 920 pixels
Height : 808 pixels
Display aspect ratio : 2.40:1
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.255
Stream size : 7.54 GiB (81%)
Writing library : x264 core 158 r2984 3759fcb
Encoding settings : cabac=1 / ref=5 / deblock=1:-3:-3 / analyse=0x3:0x133 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-2 / threads=25 / lookahead_threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=9479 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=62500 / vbv_bufsize=78125 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00
Default : Yes
Forced : No

Audio #1
ID : 1
Format : DTS
Format/Info : Digital Theater Systems
Mode : 16
Format settings, Endianness : Big
Codec ID : A_DTS
Duration : 1 h 53 min
Bit rate mode : Constant
Bit rate : 768 kb/s
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 SPF)
Bit depth : 24 bits
Compression mode : Lossy
Delay relative to video : 400 ms
Stream size : 626 MiB (7%)
Language : French
Default : Yes
Forced : No

Audio #2
ID : 5
Format : DTS
Format/Info : Digital Theater Systems
Mode : 16
Format settings, Endianness : Big
Codec ID : A_DTS
Duration : 1 h 53 min
Bit rate mode : Constant
Bit rate : 1 509 kb/s
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 SPF)
Bit depth : 24 bits
Compression mode : Lossy
Stream size : 1.20 GiB (13%)
Language : English
Default : No
Forced : No

Text #1
ID : 2
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Duration : 1 h 7 min
Bit rate : 0 b/s
Count of elements : 6
Stream size : 226 Bytes (0%)
Title : Forced
Language : French
Default : Yes
Forced : No

Text #2
ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Duration : 1 h 52 min
Bit rate : 38 b/s
Count of elements : 1100
Stream size : 32.1 KiB (0%)
Title : French
Language : French
Default : No
Forced : No

Menu
00:00:00.000 : en:00:00:00.000
00:03:28.875 : en:00:03:28.875
00:07:34.621 : en:00:07:34.621
00:11:42.201 : en:00:11:42.201
00:15:44.110 : en:00:15:44.110
00:18:37.408 : en:00:18:37.408
00:25:24.481 : en:00:25:24.481
00:31:40.357 : en:00:31:40.357
00:34:19.307 : en:00:34:19.307
00:40:07.447 : en:00:40:07.447
00:44:36.090 : en:00:44:36.090
00:49:07.778 : en:00:49:07.778
00:55:38.168 : en:00:55:38.168
00:58:57.409 : en:00:58:57.409
01:02:57.190 : en:01:02:57.190
01:10:40.111 : en:01:10:40.111
01:13:42.418 : en:01:13:42.418
01:19:33.477 : en:01:19:33.477
01:22:35.701 : en:01:22:35.701
01:25:49.061 : en:01:25:49.061
01:30:38.350 : en:01:30:38.350
01:32:48.188 : en:01:32:48.188
01:37:59.624 : en:01:37:59.624
01:45:01.045 : en:01:45:01.045

#21

This film is not HDR.
You’re not forcing anything in rc.local are you?

#24

No i haven’t issue with HDR film, only with 720p and 1080p… I haven’t touch rc.local, you want this file ?

#26

Check your TV settings as well as follow the advice given to the user above