4K Decoding - what upgrade do I need?

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I currently have a GA-Z170X Gaming 3 motherboard with a i5 6600K, 16GB DDR4 RAM and GTX970 GPU. I’ve just got a 4K TV, and plex is struggling to serve 4K. Can anyone suggest what upgrade I need to any of the above-mentioned components?

You don’t need any upgrade you just need a decent client that will Direct Play 4K e.g NVidia Shield, Amazon Fire TV 4K, Apple TV 4K etc

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I thought a decent server would send 4K directly to the TV fine, without the need for extra devices? Would a Chromecast cut it?

The client is the bit playing the stream. If it cannot play it natively, the server will transcode / reduce bitrate to something the client can handle. What client are you using? An app built into the TV?

The client came pre-installed on the Samsung NU8000 TV. Is it correct that the TV is the cause of the problem, which can only be properly rectified by an external device (Shield, Apple TV etc)?

My vote would be for a Shield. I have one and it’s a superb bit of kit. Alternatively, the Amazon devices support Plex and are better value.

I think my main problem was I was using wifi, and my router is pretty ordinary. I tried it with ethernet, and it mostly worked, but still some buffering now and then. Also, my receiver couldn’t play the sound sent from my TV via optical cable.

Edit 1: What make/model of receiver?

Since you’re using an optical cable to pass audio, you should only select Dolby Digital 5.1 (AC3 5.1) or dts 5.1 audio if possible (PCM 2.0 & AAC are OK too). The optical cable cannot pass TrueHD, dts-HD MA, or other lossless multi-channel audio. Selecting TrueHD or dts-HD audio will cause Plex to transcode the audio.

Disable subtitles during playback. Image based subtitles - PGS & VOBSUB - will force a video transcode. Plex transcodes 4K to 1080p H.264. HDR is also lost when transcoding.

The Ethernet port on most TVs is 100 Mbps. So, if you are playing a high bit rate video you may occasionally see buffering. The video bandwidth shown in Plex’s “Get Info” is only an average. You can watch the bandwidth used in real time with the new dashboard. Go to the hosted web interface, https://app.plex.tv/desktop. Select Settings -> Dashboard during playback.

Edit 2: The dashboard will also show you what is playing and if the video or audio is transcoding. What does it show when you are playing a 4K movie?

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100mbs is plenty of throughput to stream HD video. I’ve got 4k Movies 10bit HEVC streaming at avg bitrate of 64mb/s . If you’re going to use wireless, it better be 802.11n with no interference

UHD allows for three disc capacities, each with its own data rate: 50 GB with 82 Mbit/s, 66 GB with 108 Mbit/s, and 100 GB with 128 Mbit/s. That doesn’t mean the disc will use that bitrate but it certainly can.

So it’s pretty easy to see why some ripped disks could have a problem playing back through a NIC limited to 100 Mb. Remember this is 100 Mb for everything running on the TV. This isn’t 100 Mb dedicated to the app you are in. Network discovery and all the fancy protocols used on TVs for “casting” rob you of some of those bits and packets. App updating or checking the store for updates. System updates and apps “phoning home”. You won’t have 100 Mb for your use.

802.11n is “old technology” by today’s WIFI standards. It has a top speed of about 450Mb while 802.11ac is 3x faster with top speeds of 1300Mb. Obviously band and distance come into play but the faster the better generally speaking. Of course those are theoretical top speeds and your mileage will vary often to only 1/2 those speeds.

My TV and router are both 802.11ac, with about 12m distance, and no real obstacles. However, the router has no external antennas (Huawei HG658) so perhaps that’s the main issue. I’ve been meaning to get a decent router for a while, and if this fixes my connection issue I’l get it done.

Ok, so I’ve checked the file I’m testing, and the sound track is AAC 7.1. As this is being sent to my receiver from the TV via optical, is that why I’m not hearing anything?

Probably as optical is usually only good up to Dolby 5.1.

What make/model of receiver do you have?
It may not support AAC 7.1.

Try a video with Dolby Digital 5.1 or 2.0 if you have one.

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Yep, I sort of hoped that as the TV can accept 7.1, then maybe it can transform it via the optical out, but alas this musn’t be the case.

So, with my current setup (Samsung 55" NU8000 and Pioneer VSX-LX51), can anyone tell me what the best audio I can push via optical (apologies if this has already been answered, I’m just trying to clarify).

If I want to improve this, I suspect I’ll need a device to receive the Plex stream, and push it to a better new receiver - correct?

As far as I’m aware, you are limited to 5.1 / 7.1 Dolby Digital or DTS.

Overview of the interface: TOSLINK

And as far as the new equipment goes, you are correct. Streamer to receiver via HDMI now.

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Right now you are limited to Dolby Digital, Dolby Digital Plus, or AAC at 5.1 channels or less. PCM 2.0 should also work. dts 5.1 will transcode, as it is not supported by your TV.

Your receiver supports HDMI 1.4, including HDMI-ARC. It also supports TrueHD and dts-HD audio. Your TV supports HDMI 2.0, HDMI-ARC, & HDCP 2.2 (4K copy protection).

Here is one possible path forward:

  1. For 4K video, continue to use the Plex app on the TV. Limit the audio to tracks that will direct play. Limit subtitles to SRT to avoid video transcoding.

  2. Replace the optical cable with HDMI and use HDMI-ARC for the TV to Receiver audio. This will let you connect Blu-ray/DVD players, etc to the receiver and pass the video to the TV. The video will be limited to 1080p. HDMI control (CEC) may also work, allowing you to control receiver volume, on/off, etc from the TV remote (see note 2 below).

  3. If you want to play videos in Plex with TrueHD & dts-HD audio, then purchase a Nvidia Shield and connect it via HDMI to the receiver. The video will be limited to 1080p due to the limits of your current receiver. Plex Media Player on a PC is also an option, but with limits (no HDR). See note 3 below.

  4. Replace your receiver with one that supports 4K video passthrough, HDMI 2.0 or 2.1, & HDCP 2.2. It should also support TrueHD + Atmos and dts:X audio codecs. You can then use Plex on the Shield to play 4K HDR10 videos and have TrueHD + Atmos and/or dts:X audio at the same time. See note 4 regarding HDMI 2.0 vs 2.1.

Notes:
Note 1: Audio transcoding + SRT subtitles result in video transcoding. Limit audio tracks to direct play to avoid that situation.

Note 2: It looks like your receiver supports control over HDMI. Pioneer refers to it as “KURO LINK.” You’ll just have to try it to see if it is compatible with the Samsung TV. See page 44 of your receiver manual (PDF).

Note 2a: Another advantage is you can use the on screen display when making configuration changes to the Pioneer. Much easier to see the configuration on a 55" TV than the front display of a receiver.

Note 3: The Shield is the only off-the-shelf box that bitstreams TrueHD, including Atmos, and dts-HD MA and supports HDR. Note that it only supports HDR10. Videos with Dolby Vision & HLG versions of HDR will transcode. You can also use Plex Media Player on a PC to bitstream TrueHD, but HDR is not supported.

Note 4: Equipment with HDMI 2.1 & HDMI-eARC should be available this year. HDMI-eARC has the bandwidth to support lossless audio codecs such as TrueHD and dts-HD MA. It doesn’t help your current situation, but waiting for HDMI 2.1 would set you up for the future, if/when you replace your current TV. If both your TV & receiver support HDMI 2.1 & HDMI-eARC, then, in theory, you would not need an external streaming box. The Plex app on the TV could then pass TrueHD, etc to the receiver.

Edit / Addendum: The Samsung manual lists the supported audio & video codecs. See page 131 of the E-Manual (PDF). (Link from NU8000 product page).

Edit 2: Here is a nice explanation of HDMI-ARC and HDMI-eARC from flatpanelshd.com.

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Whoa, thanks so much for such a detailed response! I’ll re-read it a few times and let it sink in. Having just bought a new TV, it will be hard to justify upgrading. I think I’ll end up going down the Shield path for now. Appreciate your advice!

Sort of off-topic, but I gather that my TV can send sound to the AVR using HDMI via ARC. I tried connecting a cable from HDMI 4 on the TV to HDMI 1 on the AVR, but got nothing. When choosing the sound output on the TV, I only see built-in or optical - no setting to use HDMI. Am I missing the point, or connecting it incorrectly?