Hmm. The P600 has dedicated H.264/HEVC encode and decode engines that are supposed to be able to do faster than real-time transcoding. It looks like Plex is using the CPU to decode and the P600 to encode. Maybe that’s the issue? I realized the Plex trancode engine is using 60% CPU while transcoding. Is there a reason Plex wouldn’t do both the decode and encode on the GPU’s encoder & decoder engines?
NVidia doesn’t provide a way to use their decoder, only the encoder. See https://support.plex.tv/articles/115002178853-using-hardware-accelerated-streaming/ for more info on this.
I’m not sure if the problem is in the decoding or encoding part. It just doesn’t say.
@anon18523487 I have a follow up question to your latest comment:
I bought a P2000 this week hoping to be able to transcode 4K. My CPU has quicksync feature but since its a 4790K it doesnt have any HEVC hw transcoding features.
Does that mean that my P2000 is worthless/not gonna be able to transcode HEVC 10-bit?
I thought that the GPU would completely take over the transcoding feature 
decoding is only not supported for NVIDIA GPUs under Linux?!? 0xDECAFBAD is on Windows.
I’m sure my GTX can both decode and encode
When I transcode I’m only using the GPU for encoding. The (hw) is only next to encode. Do you have (hw) next to decode and encode with the GTX?
Decoding is less work than encoding so as long as you have a decent cpu, the decoding part should be fine. The encoding will then be up to your P2000. I don’t know the specs on that device so I can’t say if it can handle hevc 10-bit or not.
AFAIK, it’s a limitation on all platforms. On Linux, there we use VAAPI for decoding which will also appear as (hw), but this is not using the GPU.
okay, and what ist this?
Video decoding is also done by the device to output to your monitor. I can’t tell what is going on with that image. If you can produce a transcode then provide me the PMS log, I can tell you exactly what it is using for decode/encode.
This was just one example of h264 conversion for playback on an iphone.
Personally, I have a completely different problem and thought that this thread best describes the problem.
I have for about 1 week the problem that crashes the transcoder at H265. The film is not played at all. This had worked well before (with hw).
Plex Media Server.log (401.5 KB)
My guess was that 0xDECAFBAD has exactly the same problem.
I do have a transcoder crash issue that’s related to videos with TrueHD audio track which is due to a memory leak and is discussed in another thread on this forum. But that’s unrelated to my issue of slow transcoding. Which I think might be due to the CPU decoding on my old 2010 Xeon processor.
It might be related. Your PMS is also using the DXVA decoder and the NVidia encoder, which is the same combo 0xDECAFBAD has.
AFAIK, DXVA is not true hardware decoding, where it utilizes the full potential of the video card. DXVA just offloads some of the math to the GPU, which will be more intensive than dedicated GPU decoding, which we don’t have access to (NVidia driver limitation).
Could be the video card still can’t keep up with the HEVC video. I don’t know what @Kodiman06128 used to generate that graph, but that utility might help identify if your GPU is being maxed out.
I don’t have the GPU section in task manager. Not sure if it’s because it’s Windows Server OS or because I’m passing the GPU through to a VM. I used the Nvidia GPU utilization graph and nvidia-smi command line utility and it claims 10% utilization for 4K HEVC to 1080p H.264 and 40-50% utilization for 4K H.264 to 1080p H.264 which seems backwards to me.
what? 
I installed Windows 10 + PMS + “use hw transcoding” .Thats all.
Ah. I found a discussion on this. https://www.windowscentral.com/how-track-gpu-performance-data-windows-10
According to that, you need the Windows 10 Fall Creators Update and your GPU must support something called WDDM 2.0. Then that GPU tab will automatically be shown in task manager.
I just ended up ordering hardware for a new Plex server. I think my CPU decoding is what is causing my issues. Went with an i5-8600. Supposedly Quick Sync with 8th gen Core CPUs can handle 4K transcoding no problem.
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.
