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no1jam
Binge Watcher

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

For those of you who read my last post, I just purchased a Firestick 4k Max and the problem is not presenting itself. It does seem to be Roku specific, and for me only on Samsung TV's.

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spork
Newbie

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Had this problem when upgrading from an older model that was buffering too frequently. The TV is not 4k/HDR, so I just needed to correct 1080p levels. In Plex Roku app, I disabled direct play to make it QuickSync on i7-9700K . Saturation and contrast are corrected and even transcodes of huge 10bit HDR files is within the iGpu's capabilities.

Thank you to everyone participating here and on the Plex forum.

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ftballpack
Streaming Star

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Notes

- I mostly notice this with DVD TV shows, not movies so much.

- This only happens on Samsung TV's so far. I had a TCL Roku TV that doesn't do this so far, and also a Vizio with a slightly older Roku Ultra that this doesn't happen with either.

The cause of this issue has nothing to do with Samsung TVs, TCL Roku TVs, or Vizio TVs in any way. The cause is the chips in the Roku Ultra 2020, 4800x.

TCL Roku TVs are low-end TVs and can not process HEVC content, as a result, Plex, Emby, and Jellyfin transcode HEVC to AVC for TCL TVs.

Older Rokus, namely the 2019 Roku Ultra does not have color display issues with HEVC, thus Vizio TVs and other TVs will play HEVC video back correctly, with that model of Roku.

no1jam
Binge Watcher

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Cool, thanks for info. I understand what you're saying here, just a couple things:

1. Finally dragged the 2021 Ultra up to the vizio, and it indeed has the problem.

2. use 2021 Ultra on the TCL 4K tv, and it didn't have the problem.

3. TCL 4K built in roku doesn't reflect any transcoding in the Plex dashboard when playing videos.

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no1jam
Binge Watcher

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Has there been any announcement from Roku on this?

Is the problem correctable via software / firmware updates, or is it a hardware problem that won't be resolved?

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2ka
Streaming Star

Re: I think I may have this mystery solved

Thanks for your work on this.  I did some more testing and found that the problem is confined to a single field in the MKV header:  Video Transfer Characteristics.  You can leave all the rest of the fields in the header the same.  For BT.709 content, this should be set to 1, but the Roku misinterprets that setting as something else like BT.2020, causing serious tint and saturation problems. As you point out, if the field is missing altogether the Roku does a much better job, and the errors are much less severe. I think though, that it is still a bit over-saturated.   Oddly, if you set the field to 14 (which BT.2020), things look correct to me.  It is as if the Roku has those reversed.

If you remux and put the file in an MP4 container, the playback looks to me to be the same as if you set the Video Transfer Characteristics field to 14 in the MKV container.

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mbd737
Newbie

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Are you seeing the problem with number 3,  TCL 4K Roku TV?

Thanks

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ftballpack
Streaming Star

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Cool, thanks for info. I understand what you're saying here, just a couple things:

1. Finally dragged the 2021 Ultra up to the vizio, and it indeed has the problem.

2. use 2021 Ultra on the TCL 4K tv, and it didn't have the problem.

3. TCL 4K built in roku doesn't reflect any transcoding in the Plex dashboard when playing videos.

1. No surprise, the "always-on HDR" issue applies to every TV that HEVC video is played back on from an MKV container.

2. If your TCL 4K tv supports Dolby Vision, aka 12-bit video, even if the "always-on HDR" is on, it may still look decent on a television that supports Dolby Vision.

3. If your TCL TV is a 4K TV, the TV likely supports HEVC natively. It's unlikely the TV has the "always-on" Dolby Vision issue would apply as the TCL TV likely does not have the Dolby Vision upscaler the 4800 Roku Ultra has. It's a 4800 Roku Ultra "feature" that is broken.

To better illustrate the cause of the problem, I am going to reference an Amazon review. On the 4800 Roku, Roku added a "feature" that is designed to make everything appear in Dolby Vision. It's a sort of Dolby Vision upscaler. The problem is that when the 4800 Roku reads container info on HEVC, MKV files, it automatically activates the upscaler, even on Televisions that only support 8-bit video. https://www.amazon.com/review/R20GNGBWOXR7K7/ref=cm_cr_srp_d_rdp_perm?ie=UTF8&ASIN=B08G9TJWW9

As I mentioned before, the manufacturer of the Television does not matter at all. If the television natively supports Dolby Vision, the "always-on Dolby Vision" issue will likely look fine. The "feature glitch" however makes HEVC video in an MKV container look horrible on devices that only support 8-bit and 10-bit video. Since Plex, Emby, and Jellyfin convert multi-channel AAC audio and remux it into an MKV before sending it to Rokus, it means even HEVC MP4 files with multichannel AAC audio can be subject to this "always-on Dolby Vision" glitch, distorting the video on TVs that only support 8-bit and 10-bit video.

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ftballpack
Streaming Star

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Are you seeing the problem with number 3, TCL 4K Roku TV?

Thanks

Unless the TCL 4K Roku TV has the same Dolby Vision upscaling feature the 4800 has, which it likely does not, you will not see the glitch that the 4800 Roku has. aka, https://www.amazon.com/review/R20GNGBWOXR7K7/ref=cm_cr_srp_d_rdp_perm?ie=UTF8&ASIN=B08G9TJWW9

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btufail71
Newbie

Re: Severe color/contrast distortion while Plex-streaming HEVC+EAC3 videos.

Hello all, newbie here. Funny that I ran into the same issue with my 2021 Roku Ultra displaying HEVC in a reddish color saturation. I actually reset my Roku and reinstalled plex and so far the issue has been resolved. On a side note, I use handbrake to encode most of my content: I use 10-bit h265 and set all audio to AC3 5.1 640kbps. I only have a 5.1 onkyo Home theater system with Polk speakers and that's enough for me. I'm just not that big on atmos, 7.1 master master audio, etc. My receiver will decode most of those forms of audio but again I don't ever utilize it. Everything that I've encoded with handbrake using those setting plays perfectly fine. It was just those handful of videos that I had that were not that displayed this color distortion. Again,  after I reset my Roku and reinstalled plex and so far the issue has been resolved, for now.

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