4k Videos with constant buffering on Tizen

General Discussions
1

I’m having an issue when playing 4k videos on the Tizen app.

I have a 4k video downloaded from Youtube and sitting on my Plex server running on a Macbook running Ubuntu 16 with 8 cores (i7-4980HQ CPU @ 2.80GHz) and 16 gigs of RAM. This server is dedicated for plex and storage is a Synology drive mounted over nfs.

When I play this video on the Plex app on Apple TV, and on the Plex Web App in Firefox, it plays nicely, without issues neither any buffering. On htop I don’t see any transcoding happening, so it’s direct playing.

When I play it on the native Plex Tizen app on my Samsung (QN65Q80RAFXZA Flat 65-Inch QLED 4K Q80 Series Ultra HD Smart TV with HDR) over wifi (Mesh Google Wifi with three wifi points) I experience constant buffering, like every 5 seconds. I see a transcoding process running when it starts:

/usr/lib/plexmediaserver/Plex Transcoder -codec:0 vp9 -hwaccel:0 nvdec -hwaccel_fallback_threshold:0 10 -hwaccel_output_format:0 cuda -hwaccel_device:0 cuda -codec:1 opus -ss 71 -analyzeduration 20000000 -probesize 20000000 -i /mnt/4kvideo.webm -filter_complex [0:0]hwupload[0];[0]scale_cuda=w=3840:h=2160:format=nv12[1] -filter_complex [0:1] aresample=async=1:ocl='stereo':rematrix_maxval=0.000000dB:osr=48000[2] -map [1] -metadata:s:0 language=eng -codec:0 h264_nvenc -b:0 45000k -maxrate:0 60000k -bufsize:0 120000k -forced-idr:0 1 -r:0 25 -force_key_frames:0 expr:gte(t,71+n_forced*1) -map [2] -metadata:s:1 language=eng -codec:1 aac -b:1 258k -f dash -seg_duration 1 -init_seg_name init-stream$RepresentationID$.m4s -media_seg_name chunk-stream$RepresentationID$-$Number%05d$.m4s -window_size 5 -delete_removed false -skip_to_segment 72 -time_delta 0.0625 -manifest_name http://127.0.0.1:32400/video/:/transcode/session/7s0oawoyctc062obw95mw4fm/984a4472-7f86-489e-816e-5ae585b1128e/manifest?X-Plex-Http-Pipeline=infinite -avoid_negative_ts disabled -map_metadata -1 -map_chapters -1 dash -start_at_zero -copyts -init_hw_device cuda=cuda: -filter_hw_device cuda -y -nostats -loglevel quiet -loglevel_plex error -progressurl http://127.0.0.1:32400/video/:/transcode/session/7s0oawoyctc062obw95mw4fm/984a4472-7f86-489e-816e-5ae585b1128e/progress

When I play this same video from Youtube, on this same TV, I don’t experience any buffering and it plays smoothly. When I turn the stats for nerds I see the connection speed is 35 Mb/s.

So I think wifi issues are ruled out here, and it seems that Plex for Tizen is not able to direct play 4k movies and requires the transcoding which is also not efficient enough (I see all 8 cores spinning).

This is definitely sad. Not being able to experience 4k movies on my local network because of software issues is definitely a bummer, and this issue should be revisited and prioritized.

2

I doubt it is an issue with the app but a limitation of the TV. Most TV’s do not support all formats so the server needs to transcode. You can look at the server logs to see why it wants to transcode to give you a clue what the issue is.

3

I just found that this happens with every VP9/Opus video. I tried to play other non-4k videos but VP9/Opus encoded and the main process spawned the transcoding process.

So I’m assuming either Plex’ Tizen app or the TV is not able to play VP9/Opus videos? This is definitely mysterious and I’d be curious about how Youtube does (they might ship the codec with the app maybe while the Plex app just relies on whatever is playable by the underlying OS on the TV)

4

Not many TV’s support VP9, you might check the your TV’s specs. I doubt Youtube is streaming VP9 and is transcoding the video or has an optimized version that it streams.

5

So I have a similar issue. Just purchased a newer version of the TV (model="QA65Q70TAKXXV) the OP has.

Plex Server on 6600k i5 - 16GB RAM
100mb LAN on both the server PC and the TV (I’ve tried to go over wireless but the buffering is worst).
Playing directly via the Samsung Plex App

I’ve tried:

Turning off direct play and direct streaming. Makes buffering worst

Why is it still transcoding? I’ve read on other threads that certain TVs do not process DTS audio. If my 4k movie has DTS audio, this would cause audio transcoding but isnt my PC able to handle that? I know that 4K video transcoding would be an issue but not audio?

Would running everything through a 4k ROKU player and then the TV cause the stream to no longer transcode?

6

100mbit is not fast enough for 4K unless you are running very low bit rate 4K videos. If you are going to buy an external device I would suggest the Nvidia Shield Pro. It can handle anything you can throw at it. Where you may run in to an issues is if you do not have an AV receiver and connect the shield directly to the TV. Then you still may run in to transcoding the audio.

I had issues with my Samsung tv too and ended up getting the shield which too care of all my issues. I have my shield plugged in to my AV receiver which supports all the audio formats currently out.