DS423+ Transcoding

[NasNoob]

I have a DS423+ used primarily as a Jellyfin media server. I selected this model as I thought (hopefully not incorrectly) that the CPU was suitable for server side transcoding. However, I am noticing that certain .mkv files (I believe HEVC 10) are causing 80% or more CPU load during playback. What am I doing wrong? 

I have Jellyfin installed through the community app store (as opposed to docker). Maybe my Jellyfin playback settings are the issue? Is there a software tweak I am missing to optimize my setup? 


Settings: 
Hardware Acceleration - Intel QuickSync
Enable Hardware Decoding for:
   - H264
   - HEVC
   - HEVC 10bit
   - VP9 10bit
   - Prefer OS native DXVA or VA-API hardware encoders
Enabled hardware encoding
Allow encoding in HEVC format
Enable VPP Tone mapping
   - VPP Tone Mapping brightness gain: 16
   - VPP Tone Mapping contrast gain: 1
Enable Tone Mapping:
   - algorithm: BT.2390
   - mode: auto
   - range: auto
   - desat: 0
   - peak: 100
   - thread count: auto
H.265 encoding CRF: 28
H.264 encoding CRF: 23
Deinterlacing method: YADIF
Throttle Transcodes: Yes


Appreciate any help I can get!

[ed]

It seems like you've already taken several steps to optimize your setup for transcoding with Jellyfin on your Synology DS423+. However, if you're still experiencing high CPU load during playback of certain HEVC 10-bit .mkv files, there are a few additional considerations and potential optimizations you can explore:

Transcoding Settings: Your transcoding settings look reasonable, but you might want to experiment with adjusting the H.265 encoding CRF (Constant Rate Factor) value. Lowering the CRF value can increase video quality but will also increase CPU load during transcoding. Conversely, raising the CRF value can reduce CPU load but may result in lower video quality. Try adjusting this value to find a balance between CPU usage and video quality that works best for your setup.

Playback Settings: In the Jellyfin playback settings, make sure that Direct Play and Direct Stream options are enabled whenever possible. Direct Play streams the media file without any transcoding, while Direct Stream only transcodes the audio or video codec that is not supported by the playback device. By enabling these options, you can reduce the need for transcoding and lower CPU load during playback.

Verify Hardware Acceleration: Double-check that hardware acceleration is properly enabled and functioning on your Synology NAS. You've mentioned that you're using Intel QuickSync for hardware acceleration, but it's worth confirming that it's being utilized effectively by Jellyfin. You can check the Jellyfin dashboard or logs to see if hardware acceleration is being used during playback.

Media File Analysis: Analyze the specific HEVC 10-bit .mkv files that are causing high CPU load during playback. Check their encoding profiles, bitrates, and any other relevant technical details. It's possible that these files have particularly demanding encoding parameters that are challenging for hardware transcoding to handle efficiently. Consider re-encoding problematic files with more optimized settings if feasible.

Update Software: Ensure that your Synology NAS firmware, Jellyfin server, and any related packages are all up to date. Sometimes performance improvements and bug fixes are included in software updates that can help alleviate issues like high CPU load during transcoding.

Community Support: Since you're using Jellyfin via the community app store, consider reaching out to the Jellyfin community forums or Discord server for additional assistance and insights. Other users may have encountered similar issues and could offer helpful advice or troubleshooting tips specific to Jellyfin on Synology NAS devices.