Hi
This is probably a noob question but I am still learning this . I have a plex server on a Windows computer and also a bunch of movies that are mp4 and mkv’s. The same PC also runs my CCTV system
I noticed when I play a 4k mkv the movie would not play smoothly and stutter. Checked my CPU on the plex server ( also cctv system) and it was maxed at 100%
Did some isolation and found the transcoding 4k was using 98% CPU!
that with the CCTV going would bring it to its knees
so I turned off the CCTV and it started playing ok. It didnt even have enough CPU to play a 1080p mkv file
mp4 though I noticed it did not need to transcode it as the "plex transcoder.exe " file was not running when playing mp4
so is this always going to be the case when playing mkv?
Should I always try to get or encode files to mp4?
Just would like to know so I can do this myself in future
I am running my plex server on a i5-3570k with 12GB of ram , Movies store on a Synology DS218play
Not all devices support mkv files so Plex must transcode movies and it requires a lot of power from your CPU. The best thing u can do is to encode all your files in a format that is compatible with all your devices.
The most used formats are: MP4/AAC
I am sorry, but I disagree. The container format mkv or mp4 is definitely not the problem. Converting from one to the other, called remuxing, is a operation with little demand on hardware resources.
However, you mention “4k.” If - for whatever reason - the server decides to transcode a non-trivial 4k stream to a lower resolution, then that is a heavy load of even a decent CPU.
I suggest to use the dashboard to check what actually is happening.
Listen to eckarth. He is telling you how things actually work. I have no idea why XxidroxX thinks the container matters with regards to when and why a file requires transcoding, but he may be thinking of remuxing which is what happens when everything but the container is supported. For transcoding it’s all about the actual video or audio codec and subtitle format used. The latter only matters if a subtitle format is not supported by the client and must be rendered on the server side. This does however require a transcode of the video as well. For audio the client can’t handle a media server typically only transcodes the audio and remuxes the rest although Plex seems to go with a complete transcode of everything whenever I have come across unsupported audio formats.
When a media server transcodes the video the amount of resources needed will scale mostly with the resolution of the source file. This is because even if you are converting to a low bitrate 720p quality all the original pixels need to be considered to reproduce an accurate image. That’s not to say a higher quality setting will have no impact on the transcoder, but the impact is much lower than the impact of swapping say a 4k source file for a 1080p version.
I’m aware that I’m repeating stuff that’s already said here. I just fought it may be useful for somebody that’s new to this to get a brief explanation of why things are done in a certain way and not just get a rundown of what’s actually happening
From what I have read and experienced, the easiest way to reduce CPU load is to add a display adapter (GPU) that will offload the transcoding burden. I have had good luck with Nvidia card. Got immediate benefit after installing on my Windows PC.
A video card can help, but your mileage will vary depending on the source file as the hardware accelerated encoders don’t support every kind of input. At least that’s what it was like a couple of years ago. They may have improved now.
thanks yeh I read that FAQ, Some if it I dont understand but remember I mentioned my CPU was even bottle-necked playing a mkv 1080p file when my CCTV system was running. I guess I could upgrade the CPU as its a bit old and I am asking it to do a lot but if I grab mp4’s it doesnt transcode anything. I just plays
I checked this in task manager on the plex server box
AnywayI will still check out the dashboard and report back!
Write on the blackboard 50 times: “I promise not to transcode 4K video ever again.” Then skateboard home and pop a wheelie off the car roof.
Seriously, if you do not have a 4K TV do not play 4K material.
Your system is not capable of transcoding 4K. Without a Plex Pass, your system can handle one 1080p transcode, not including the load of the CCTV system.
The AAC 7.1 audio may also be an issue. Choose an audio format that does not transcode.
Ideally you want both video and audio to direct play.
