Hardware transcoding doesn't appear to work properly

Plex Media Server Desktops & Laptops
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Server Version#: 1.29.1.6316 (Windows 10 Pro)
Player Version#: Plex Web Version 4.92.0, Samsung for Samsung, Client Version 5.48.1, Platform version 4

I recently upgraded my desktop to the following spec: 16GB RAM, I7-3770s and GTX 1650 GPU so I thought I would try hardware transcoding as software transcoding wasn’t working for 4k media. After enabling it, it still doesn’t work well. Videos take a while to start and constantly buffer. The strange thing is that looking at the servers utilisation only the CPU increases but nothing on the GPU, even though the Plex server dashboard says that its hw transcoding. Am I right in thinking that the GPU usage should go up since this is what should be doing the hardware transcoding? I haven’t been able to find out what’s causing the issue. I’ve tried with the web client on Edge, Firefox and Chromium as well as the Samsung TV app.

I’ve attached logs, before and during transcode utilisation screenshots. On the logs the transcode timestamps start at ‘Oct 20, 2022 17:34:35.560’ for an example of when I was trying.

Logs: PrivateBin

Statistics: PrivateBin

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If you have not already done so, use the 64-bit build, not the 32-bit build. Plex added support for zero-copy hardware transcoding in the 64-bit builds. It should increase transcoding performance, since Plex won’t have to move as much data between the GPU and system memory.

You can install the 64-bit build over the 32-bit build. The installer will recognize and remove the 32-bit installation.

Only the Plex binaries are changed. The Plex Data Folder with the Plex database is not touched.

Note: If you go from 64-bit to 32-bit you must manually uninstall the 64-bit version first. The 32-bit installer is not aware of the 64-bit version.

If the 4K media is HDR, then it must also be tonemapped to SDR when transcoded.

On Windows systems, Plex has no support for tonemapping using Nvidia GPUs. Tonemapping will use the CPU instead.

As a test, turn off tonemapping in Settings → Transcoder and transcode a 4K HDR video. The colors will be wrong, but playback should be smoother.

Unfortunately, until Plex supports hardware accelerated tonemapping on Windows, transcoding 4K HDR media will be problematic.


HDR to SDR Tone Mapping

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Any idea when this might be or if it’s even being worked on?

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Thanks, installing the 64bit version seems to have resolved it. I’ve been using Plex for years and never realised that I had the 32bit version installed. Strangely, I left tonemapping on and it still transcoded a HDR film perfectly using the GPU.

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Plex never announces such timelines.

Glad things are working for you.

The Windows 64 bit version is recent, released on September 14, in 1.29.0.6209.

Zero-copy transcoding for Nvidia GPUs was added to the 64-bit builds a few days later, in 1.29.0.6219.

AFAIK, tonemapping on Windows still uses the CPU. I’ve seen no posts otherwise.

Apparently the performance boost provided by zero-copy transcoding makes tonemapping on Windows feasible.

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