4K HEVC HDR to 1080p Enhanced Player

[Treverr]

Server Version#: Version 1.19.4.2865
Player Version#: tvOS 2.18.1 (15619)

I have found a huge issue for tvOS Clients who are playing back in 1080p from a 4K HDR HEVC source with the Enhanced Player.

When playing back the content with the following settings:
Media:

Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 5.49 GiB
Duration                                 : 3 h 1 min
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 339 kb/s
Encoded date                             : UTC 2019-08-27 03:52:10
Writing application                      : mkvmerge v35.0.0 ('All The Love In The World') 64-bit
Writing library                          : libebml v1.3.9 + libmatroska v1.5.2 / Lavf58.20.100

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@Main
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 3 h 1 min
Bit rate                                 : 3 492 kb/s
Width                                    : 3 840 pixels
Height                                   : 1 608 pixels
Display aspect ratio                     : 2.40:1
Frame rate mode                          : Constant
Frame rate                               : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.009
Stream size                              : 4.42 GiB (80%)
Writing library                          : x265 2.9:[Windows][GCC 8.2.0][64 bit] 10bit
Encoding settings                        : cpuid=1111039 / frame-threads=5 / numa-pools=32 / wpp / no-pmode / no-pme / no-psnr / no-ssim / log-level=2 / input-csp=1 / input-res=3840x1608 / interlace=0 / total-frames=0 / level-idc=0 / high-tier=1 / uhd-bd=0 / ref=3 / no-allow-non-conformance / no-repeat-headers / annexb / no-aud / no-hrd / info / hash=0 / no-temporal-layers / open-gop / min-keyint=60 / keyint=600 / gop-lookahead=0 / bframes=4 / b-adapt=0 / b-pyramid / bframe-bias=0 / rc-lookahead=15 / lookahead-slices=8 / scenecut=40 / radl=0 / no-intra-refresh / ctu=64 / min-cu-size=8 / no-rect / no-amp / max-tu-size=32 / tu-inter-depth=1 / tu-intra-depth=1 / limit-tu=0 / rdoq-level=0 / dynamic-rd=0.00 / no-ssim-rd / signhide / no-tskip / nr-intra=0 / nr-inter=0 / no-constrained-intra / strong-intra-smoothing / max-merge=2 / limit-refs=3 / no-limit-modes / me=1 / subme=2 / merange=57 / temporal-mvp / weightp / no-weightb / no-analyze-src-pics / deblock=0:0 / sao / no-sao-non-deblock / rd=2 / no-early-skip / rskip / fast-intra / no-tskip-fast / no-cu-lossless / no-b-intra / no-splitrd-skip / rdpenalty=0 / psy-rd=2.00 / psy-rdoq=0.00 / no-rd-refine / no-lossless / cbqpoffs=0 / crqpoffs=0 / rc=abr / bitrate=3500 / qcomp=0.60 / qpstep=4 / stats-write=0 / stats-read=0 / ipratio=1.40 / pbratio=1.30 / aq-mode=1 / aq-strength=1.00 / cutree / zone-count=0 / no-strict-cbr / qg-size=32 / no-rc-grain / qpmax=69 / qpmin=0 / no-const-vbv / sar=1 / overscan=0 / videoformat=5 / range=0 / colorprim=9 / transfer=16 / colormatrix=9 / chromaloc=0 / display-window=0 / max-cll=0,0 / min-luma=0 / max-luma=1023 / log2-max-poc-lsb=8 / vui-timing-info / vui-hrd-info / slices=1 / no-opt-qp-pps / no-opt-ref-list-length-pps / no-multi-pass-opt-rps / scenecut-bias=0.05 / no-opt-cu-delta-qp / no-aq-motion / no-hdr / no-hdr-opt / no-dhdr10-opt / no-idr-recovery-sei / analysis-reuse-level=5 / scale-factor=0 / refine-intra=0 / refine-inter=0 / refine-mv=0 / no-limit-sao / ctu-info=0 / no-lowpass-dct / refine-mv-type=0 / copy-pic=1 / max-ausize-factor=1.0 / no-dynamic-refine / no-single-sei
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant

If I convert to 1080p with the Enhanced Player (Use old video player OFF), it looks like this:

If I turn Use Old Video Player ON, it looks like this:

There is a huge and noticeable difference between the two, Enhance Player moves the movie unwatchable IMO. I have a number of people who can’t stream 4K or don’t have 4K ATV’s and I suspect this is affecting them too. The ONLY difference between those two images in the video player everything else is exactly the same. This doesn’t seem to happen with 4k h.264 but I also don’t think its HDR, I believe this is a mapping issue with the colors? But that’s just my guess. I tested this with other movies, 4K (HEVC Main 10) did not have this issue. But every movie that is HDR is totally botched and pretty much unwatchable with the Enhanced player, which is default on for everyone now if I recall correctly.

Server logs:
Plex Media Server Logs_2020-05-27_01-37-44.zip (4.5 MB)

Client Logs:
logging-4.zip (1.0 MB)![Screen Shot

[Treverr]

@anon18523487 - do you have any thoughts on this?

[sergiou87]

Hello @Treverr!

Unless I’m misunderstanding the issue, I think the problem is actually a limitation of the transcoder: when HDR video is transcoded, the HDR info is “lost” and the transcoder won’t apply tone mapping to compensate that loss, so the video will look like bad (dull and washed out colors) in all clients. If you try the same video in another client, forcing transcoding, you should see the same, which would confirm my theory.

Adding tone mapping support to the transcoder is in the server team’s backlog, but for now that’s the result you will get

Reading a second time, and paying more attention to the screenshots, I guess you’re talking about the color banding with the enhanced player, which indeed makes everything even worse Do you see that with HDR video (without transcoding it)?

[Treverr]

Hi @sergiou87,

This ONLY happens with the enhanced player, if I transcode this using the original player on iOS/ATV it doesn’t do the color banding issue. If it’s a transcoding issue, wouldn’t we have that on both? Unless it’s doing something different during the transcode for the different players.

I don’t see it when I’m not transcoding. This issue only seems to appear when you transcode from 4K HDR to a lower quality (most commonly 1080p) and have the “enhanced player” enabled.

[sergiou87]

So when you play 4K HDR without transcoding it looks good? If so, try this: inside the app go to Settings, look for Display Type and set it to SDR. Then, play that file again (without transcoding) and tell me if it looks good.

After that, you can set Display Type back to HDR or Auto, whatever you had

[Treverr]

Setting this to SDR does do this with the Enhanced Player but does not do this with the enhanced player off (i.e. Use Old Video Player ON)

[Treverr]

@sergiou87

[sergiou87]

I can’t reproduce this issue here. Could you share a specific movie with me? One where the issue is obvious. You can now share videos individually with people, no need to share a whole library.

Thank you!

[Treverr]

Sorry for the delay we just moved this week, but I’m not sure how to do this and I didn’t see any support documents on it. I only see the ability to share a whole library.

[sergiou87]

No worries, this support article should help: https://support.plex.tv/articles/shared-media/

[Treverr]

@sergiou87 I shared the movie I have listed here in the issue. The set up I have is:

• Enhanced player (old player off)
• Convert to 1080p (non HDR)
• Apple TV 4K

[Treverr]

@sergiou87 were you able to reproduce this issue? Or need anything from me?

[sergiou87]

Not yet, sorry, I’ve been busy with other stuff But I haven’t forgotten about this! I’ll let you know when I take a look, hopefully soon…

[sergiou87]

I was able to reproduce the issue, I still think it’s a problem with the transcoder, but only happens with the enhanced video player because the transcoder behaves a bit differently for it.

What specific quality do you choose to cause this problem? 1080p as resolution, but what bitrate?

[Treverr]

I was transcoding to 20mbps I believe, the high setting. Were you seeing this on multiple bitrates too?

How does this get handled on a client that is not a 4K, say such as a 1080p Apple TV, does the client load the 4K quality but only display 1080p? Or will it transcode it to 1080p?

[Treverr]

I just tested this again, its 1080p HD (High) my dashboard shows 17mbps

[sergiou87]

Our transcoding expert is looking into a bug that might be the cause of this problem