4K Direct Play Issue - My first foray into trying to use 4K. FireTV Gen2 @ TV

Plex Media Server NAS & Devices
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I finally purchased a 4K TV so I thought I would try my luck with a 4K movie off my server. I am running UnRaid on a small mini-ITX box with an i3-4150 and 8 GB of RAM. I assumed it would direct play through the FireTV Gen 2 box I have but it must be trying to transcode the stream as the app in FireTV says the Server is not powerful enough to support playback. It then reverts to 1080P and plays but stops every few mins to buffer. Looking at the Web interface I see CPU usage is at 100% during this kind of playback with a 25Mbps bandwidth. After the initial try I can’t get it to revert back to 4K. The file is an H265 encoded movie. To compare I tried a standard 1080P movie and it runs with no CPU load and about 8Mbps bandwidth. I assume this is how direct play should work as the box is not really doing any work.

Any direction I can go to get this running is appreciated. I know the requirements for transcoding are very high, but I don’t think in this case within my house I should be transcoding. So maybe I’m mistaken that the FireTV box supports the passthrough. It says it will do 4K but it is a little older. 4K does work with Netflix and Prime on the same box though.

Server Version#: 1.16.0.1226
Player Version#: FireTV App

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So I just watched that same file on my laptop (1080P display). The movie for the first half only stalled once, then maybe 7 times during the second half. The load I saw on the server was the same @100% but it managed much better than when I was using the FireTV box. It seems odd as the laptop was also doing it wirelessly when the FireTV has ethernet. So maybe some of the problem lies within that box.

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Short Answer:

You’re limited by the AFTV Gen2 and the 4th gen CPU. The AFTV has issues direct playing 4K HEVC video and the i3 4th gen CPU is not powerful enough to transcode 4K HEVC video.

Suggestions:

  • Consider a Nvidia Shield, Roku, or Apple TV 4K for streaming 4K media with Plex.
  • You PMS system can stream 4K as long as it direct plays (I run PMS on a Synology NAS w/ a Celeron. No problem w/ 4K as long as it direct plays.).
  • If you do upgrade your server, go with an 8th Gen or later Intel processor. They support hardware accelerated transcoding of 10 bit HEVC video.
  • If your TV does not support 4K, then don’t bother playing 4K media (you don’t mention make/model). Transcoding always reduces quality. If your TV is 1080p, then go with 1080p media.
  • Also see this thread: Plex, 4K Transcoding and You

Long Answer:

  • General Comment

Even though some AFTV devices are rated for 4K playback, there are issues with Plex being able to direct play 4K media. FYI, I’m not pointing the finger at Plex, it could be an AFTV or Android TV issue.

I have an AFTV Cube. I cannot get it to direct play 4K HDR movies using the Plex app.

I also have a Nvidia Shield. It direct plays 4K HDR10 movies w/o issue (the Shield does not support Dolby Vision or HLG video, both of which will transcode).

  • Specifics

I’m not sure you can avoid transcoding 4K HEVC content. Also, your PMS system is very underrated for transcoding 4K material. Reference: What kind of CPU do I need? and i3-4150 Passmark.

Here’s some things that might help, but no guarantees it will eliminate buffering when transcoding.

  • Be aware of AFTV Gen 2 Box Limitations

Note the Tech Specs for the box, specifically that the output is 8-bit video. So, if the video you are playing is HDR or 10-bit SDR, you’ll never see the benefit.

If possible, chose an AAC, AC3, or dts audio track, as they will direct play. The AFTV box does not support lossless audio such as TrueHD or dts-HD MA. AFTV devices also do not support dts, but, if I remember correctly, it will be decoded on the AFTV device, not transcoded on the Plex server. Plex transcodes audio on the CPU, so choosing an audio track that direct plays will take some load off of the CPU.

Be aware of subtitle limitations. With Android TV devices, if the audio is transcoding, and subtitles are enabled, the video will also transcode. This doesn’t matter with 4K HEVC, as it will probably transcode anyway, but something to keep in mind when playing standard 1080/720/480/etc videos. FYI also applies to Plex Smart TV app for LG, Samsung, etc.

  • Enable Hardware Acceleration

The graphics processor in 4th gen Intel CPUs does not support hardware accelerated decoding of H.265 video. However, it can still accelerate the encoding to H.264. This will take some load off the CPU, although it may still hit 100%.

PMS Settings -> Transcoder (show advanced). Check box for Use Hardware Acceleration when possible. Leave Transcoder Quality on Automatic.

My setup:

Nvidia Shield <-- HDMI --> Denon 4300 <-- HDMI --> LG B7 OLED
and
AFTV Cube <-- HDMI --> LG B7 OLED

PMS running on Synology DS918+ NAS.

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Thanks for the info. It sure sounds like my AFTV box may be holding me back. I knew my little i3 would never transcode 4K but in this setup I had assumed it would direct stream. My TV is 4K but my laptop is not, and I was very surprised at how well it did take the 4K source file down to 1080P.

I may try a few other 4K video files with alternate audio and encoding to see if any pass through the AFTV properly, but it sounds like I may have to finally give up on them. I do love the box and remote though, and the speed of the interface has always been great.

I was looking to update the box and saw yesterday that the new Ryzen 9 just crushed the Passmark leaderboard. Scored over 34000 and its $499. So I may go that route. Everything else in the top 10 is over $1200.

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If I might make a suggestion…

Focus initially on having the media direct play, instead of a server that can transcode 4K. You’ll have better video quality and spend less, at least to start.

For example, you could go with a 4K HDR capable Roku and restrict audio to only what your TV supports, probably AAC & AC3, and maybe DTS. You’re out ~$100 USD and have a setup that will direct play 4K HDR movies.

If you’ve a soundbar/receiver/etc that handles TrueHD + Atmos and dts-HD, then look at a Nvidia Shield. The Shield will passthrough the audio stream to the receiver/soundbar. You won’t have to worry about whether or not the audio transcodes. As far as I know, the Shield is the only off the shelf box that will passthrough TrueHD, TrueHD + Atmos, dts-HD MA, & dts:X.

Remember that transcoding always reduces quality. Plex transcodes everything to H.264 8-bit, so if you’re transcoding H.265 video a) you’ll lose any HDR; b) PMS doesn’t tonemap, so colors will look washed out for transcoded HDR video; and c) bandwidth requirements will increase, since H.264 is less bandwidth efficient than H.265 (could be an issue w/ wireless clients).

Regarding the server, one with a new Ryzen would be nice (My current desktop is 5 yrs old, so I’ve got the “itch” for a new build myself :slight_smile:). However, it is not necessarily required.

You’ve a Plex Pass, so you can take advantage of hardware accelerated streaming. You might be able to drop a GTX 1050 video card into your current server and have a system that will transcode 4K video. I don’t use Unraid, so cannot say how well hardware accelerated streaming is supported (support varies by OS). Others on the forum can hopefully chime in with details.

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Does the older Roku Ultra work this way. It looks by the specs that it passes almost all the audio, and I prefer it because it has an Ethernet port instead of the typical USB dongle wireless. I can get one of those for $60-70 which would be an easy test.

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Is that the Roku 4? If so, it looks like it will work. The comparison sheet (PDF) I found says it supports HDR and Dolby/dts passthrough over HDMI.

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Well the Roku showed up today, and it didn’t really change the issue. It still pegged the CPU in the server to 100% but it thought my connection wasn’t fast enough. I assume its just confused as its wired ethernet and the server showed the same high load.

I tried two versions of Captain Marvel, one at 7.2 and one 11.4 video bitrate and although the server is still doing the work it plays fine on the lower bitrate version with the system running about 92% capacity. I have not messed around much with the Roku and audio to see if that is the issue. I was thinking of using Premiere to strip the audio completely and just put the video on the server to see what happens. Without audio the setup should pass it without any issue.

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Also I’m curious what I should be setting the TV at. In my setup the HDMI from the Roku goes to the TV and then the TV puts out Optical to my old soundbar.

The TV has options for Auto, PCM, Dolby Digital and Bitsream. My soundbar is an old Vizio that doesn’t decode anything. It merely take a stereo source and uses SRS TrueSurround to faux the effect. I had tried Bitstream but don’t know if maybe there is a setting I should be using instead.

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I was finally able to sort this out. The Plex app for the Roku is not nearly as user friendly as it is in the FireTV. I have to stop the stream and select the Original Quality Video stream for 4K videos. For instance Thor was a 19Mbps stream but the Roku Plex app always tries to play it at 12, hence the transcode. Every time I have to manually go in and select Original stream. Then it will direct play the video and only transcode the Audio.

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The Gen 2 Box 4K can not do 4K HEVC play back neither can the Cube. However the new Fire TV 4K Sticks can. I went down this rabbit hole of testing and did temporarily switch to Roku Streaming Stick+ that could do 4K but it wasn’t reliable and the wife did not like the interface, exchanged it for the New FireTV 4K stick and have not had any issues with it and able to direct play high bit-rate 4K’s (90680 kbps) without issues.

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I much preferred the FireTV box as well. The Roku has its ups but it is super finicky with subtitles where the FireTV never had an issue (and was easily able to switch them during playback, the Roku stops while selecting, what a pain) and this business of having to manually select the stream is junk.

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