Direct Play / Streaming jitter on Full HD but playing using VLC / WMP is fine...

General Discussions
1

Hi everyone,

I’ve always struggled to get 1080p to work and decided to try and tackle it once and for all!

I use various clients - but mainly my Xbox One, alongside my Surface Pro 4 and a dedicated Windows HTPC with PHT on it.
I have a physical “server”, where I have a VM dedicated to running my PMS. I have an AMD A8 on the host with 4 core assigned and 6Gb RAM. The VM does nothing else other than host PMS. The server is connected to my LAN via a USB 3.0 802.11ac adapter.

720p video files normally run fine using either Direct Play or transcoding to around 3Mbps.

However, I simply cannot get 1080p quality files to play without substantial jitter to the point where it’s unwatchable. When doing so on my Windows PHT device and looking at the realtime stats, it seems that the cache is exhausted and then the video pauses until the cache is re-populated. Naturally, I’ve got my cache set to 30%.
The same issue happens with my Xbox One, and on my Surface Pro 4.

If I set to transcode the 1080p media instead of Direct Play, I never see any output. I think this is because transcoding the 1080p media is simply too much for the CPU I’m using server side. Again, 720p content can be transcoded without any issues, as well as often using Direct Play.

Now I’ve always thought that I can’t play 1080p directly (without transcode) as my network simply won’t sustain the throughput required. And as mentioned above, transcoding 1080p to suitably high quality is too much for my VM’s CPU.

BUT

Through shear frustration, I’ve managed to play a number of 1080p movies from the PMS VM from my HTPC (with PHT on it) and my Surface (with the Windows Store App). I’ve achieved this, simply by browsing to the UNC path (\plexserver\movies…) and playing the file directly with Windows Media Player or VLC.

Now this in my mind PROVES that the network is up to the task of streaming the files at 1080p (native res) as I’m doing so. The only time I cannot do this is when I’m attempting to do the same thing (Direct Play/Stream) via Plex itself. This is true on all of my endpoints.

Can someone help explain why this is? If I can UNC to a file and play with VLC or WMP (as long as I have K-Lite Codec Pack installed, naturally!), then why when I attempt to play the same file on the same device using Plex via Direct Play/Stream does the jitter make it unwatchable - usually within the first few minutes.

Apologies for the lengthy post. Any insights or suggestions most welcome!

Thanks - Steve

2

The first thing to achieve Direct Play is to change the quality preference on the client to ‘Original’.
in PHT it is under Settings - Network - Quality - Local - ‘Direct Play’
(you should switch to OpenPHT, btw.)

Every Plex client has such a quality preference. If this is not set to maximum/Original, then the server will activate transcoding to restrict the bitrate to the selected value. This will then lead to the problems you experience if the server’s cpu is not up to the task.
That being said, an A8 (which type exactly?) should be able to transcode at least one 1080p stream if necessary - unless it is a HEVC encoded file or a direct rip with VC-1 video codec.

Please show also a mediainfo XML of an affected movie.