Synology DS920+ NAS Plex 4K, 1080p and 720p Tests (H.264 & HEVC)

Transcoding 4K Media on the DS920+ NAS Plex Media Server

Transcoding on a NAS such as the DS920+ device is the ability for a multimedia file to be changed from it’s existing format or codec to one that is better suited to the destination device. In this file access, the DS920+ NAS is the host device and the device you want to play the file is the client. This is the case of whether you are using Plex or not. Transcoding is typically required when a media file is more recently released than the client device that is accessing it, so the newer compression or playback format is unknown to the device you want to access it with. Alternatively, you want to access the movie or music on your DS920+ and do not want to use the original file in its full size. Transcoding can enable you to stream a much smaller version in weight or resolution if needed. In a popular program such as PLEX, smooth playback is essential, and with the plex media server application on the DS920+ NAS using a larger percentage of CPU and Memory than most programs, it is very useful to know the plex transcoding abilities of any NAS.

Why should you factor transcoding with a Plex Media Server on a DS920+ NAS

When you install a Plex Media Server on your DS920+, you should know that plex is not the answer to all of your media prayers. It has some limitations and depending on the NAS you use, these limits can be annoying. You will most likely have media files in a large collection of different formats and there is no guaranteeing that these are going to be compatible with TVs, iPads and Smartphones that you wish to watch them on. Although you will have a version of the Plex app on the viewing device, that app will still be locked to playback the supported media types on that device.

So if your phone does not support .MKV or .MOV, then neither does the plex app you installed on it. However, this is where transcoding comes in again, as the plex media server will use the NAS system resources to change the file to a version/format that it CAN play. What makes transcoding with Plex different to ordinary transcoding is that often, the NAS (in this case, the DS920+) will not let the plex use the transcoding engine inside. This is not the end of the world, as it will use raw system power instead. The result is that where a regular transcode outside of plex will use 20-30%, in plex it could go as high as 70-80%. This is why it is important to know how well a plex NAS will transcode, as if it will happen regularly, it could potentially slow down the general use of your DS920+ NAS.

Which Plex supported client devices require transcoding from the DS920+ NAS

Destination devices range greatly and are often referred to as the client device. Common client devices that your DS920+ device will be accessed by are often:

  • iPad or Android Tablet
  • iPhone or Android Smartphone
  • Smart TV or DLNA supported monitor
  • MacBook, Laptop or Netbook device
  • Sound systems such as Bose, Sonos and Sony DLNA systems
  • Home Theatre Systems
  • Network and internet-enabled gaming consoles such as PS4, Xbox One and Nvidia Shield

Transcoding between a DS920+ and your media can be of tremendous benefit for those with limited internet bandwidth, download limits or low powered devices whilst using the plex client application.

What are the Specifications of the DS920+ NAS?

The specifications for the DS920+ NAS are below and like all NAS devices, the CPU and Memory play a big part in how well it performs at transcoding both in and out of plex. The key factors to consider are if the device features an x86 or ARM-based CPU, does the DS920+ CPU feature a transcoding engine and how much RAM the device arrives with for multiple transcoding tasks. Below are the DS920+ specs:

The Synology DS920+ 4-Bay NAS – £550+

SPECS CPU MEMORY TRANSCODING ENGINE: YES 1080P Support: YES 4K Support: YES Transcoding Support: YES

CPU Model Intel Celeron J4125
CPU Architecture 64-bit
CPU Frequency Quad Core 2.0 burst up to 2.7 GHz
Hardware Encryption Engine (AES-NI) Yes
Memory Options 4GB DDR4 SODIMM 2666Mhz in Base Model (Max 8GB)


Codec h264 Decode / Encode
Codec h265 8bit Decode
Codec h265 10bit NO
Codec VP8 Decode / Encode
Codec VP9 Decode / Encode
Codec VC-1 Decode
Codec AVC Decode / Encode

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What is the difference between H.264 and H.265 4K Media on a NAS

H.264 and H.265 are common codecs of modern digital media. H264 is also referred to as AVC by experts (Advanced Video Coding) and is considered the standard for video file compression. This allows for media originally created for large-scale entertainment to be recording, compressed, and distributed to the home and smaller-scale production of digital video content watched by you, the consumer via Plex.

H265 is the newer and more consumer-friendly alternative to H264. It is also known as HEVC (High-Efficiency Video Coding) and was developed in order to resolve issues of enormous 4K media files being just too large for your client device to playback. H.265 has become so popular and data saving that chances are that the YouTube clip, iTunes media or iPlayer content you watched was in .265 and HEVC. Typically a modern NAS such as the DS920+ will playback with JUST H.265 or it will Playback both H.264 and H.265. The latter pretty much being exclusive to x86 or AMD based NAS CPU devices.

The DS920+ NAS Plex Tests – Idle/Standby

To get a better idea of what is considered ‘normal running’ in plex, we installed plex media server, along with a handful of video files that covered SD, 720p, 1080p and 4K, each at either H.264, H.265 (HEVC), UHD, 10bit or a combination of some/all of them. Here is how the NAS looked when in standby/idle (I have circled the important things to look at:

Synology DS920+ NAS Plex Test 1 – 720p 0.7Mbps 23FPS – How well does it perform?



Synology DS920+ NAS Plex Test 2 – TARNSCODE 720p 0.7Mbps 23FPS –TO– 480p 1.5Mbps – How well does it perform?



Synology DS920+ NAS Plex Test 4 – 1080p 1.9Mbps 23FPS – How well does it perform?



Synology DS920+ NAS Plex Test 5 – Trancode 1080p 1.9Mbps 23FPS –TO– 720p 2Mbps – How well does it perform?



Synology DS920+ NAS Plex Test 6 – 1080p 3Mbps H.264 30FPS – How well does it perform?



Synology DS920+ NAS Plex Test 7 – TRANSCODE 1080p 3Mbps H.264 30FPS. –TO– 480p1.5Mbps – How well does it perform?



Synology DS920+ NAS Plex Test 8 – 1080p 100Mbps H.264 30FPS – How well does it perform?



Synology DS920+ NAS Plex Test 9 – TRANSCODE 1080p 100Mbps H.264 30FPS TO 10Mbps 1080p – How well does it perform?



Synology DS920+ NAS Plex Test 10 – TRANSCODE 4K 120Mbps H.265 10BIT 30FPS Automatic Plex Settings – How well does it perform?



Synology DS920+ NAS Plex Test 11 – TRANSCODE 4K UHD 200Mbps H.264 30FPS TO 720p 4Mbps – How well does it perform?



Synology DS920+ NAS Plex Test 12 – TRANSCODE 4K UHD 400Mbps H.265 30FPS TO Plex Recommended – How well does it perform?



I hope these Plex Media Server 4K results were of use to you and this helps you consider which NAS you wish to you buy in 2020, whether it is the DS920+ or something more or less suited to your needs.

Read the Synology DS920+ NAS Drive Review Below

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    2 thoughts on “Synology DS920+ NAS Plex 4K, 1080p and 720p Tests (H.264 & HEVC)

    1. i know you enabled hardware transcoding make my cpu hurt, if you was using docker did you correctly sort the hardware transcoding? as you didnt actually show the screen that would also show the type of transcoding it is doing on the main dashboard?