Transcoder reverting to Software (QSV core i5-7400)

Channels DVR Server Troubleshooting
#1

I had hardware transcoding enabled (I run on a core i5-7400 w/ QSV available), but when I just went to double-check, the settings page reads "Transcoder Software", with no selection to switch it over to Hardware. I was having an issue last week related to the transcoder, and during troubleshooting that issue, I restarted channels DVR, and the option to select hardware returned.

Any way I can tell why hardware transcoding sometimes disappears?

The computer this runs on does share a docker running plex, which also takes advantage of QSV transcoding, but I wasn't aware of an artificial stream limit (a la NVENC) that would disallow multiple programs to utilize it.

I'm currently running Version 2020.10.30.2052

#2

Did you recently update your OS? Ubuntu-based distros changed the group that own /dev/dri from video to render (or something similar, I can't fully remember).

You may want to double-check the permissions of the device, and then ensure that what user runs the Channels DVR server has permission to access the card.

(Is Channels running in the same container as Plex? That part of your post wasn't clear, so perhaps explaining your setup a bit more might give us a little better idea of how to help.)

#3

It did look like /dev/dri/render128 was switched to the render vs. video group. I haven't recently updated the OS, so it does seem strange. I went ahead and added the user running channels-dvr to the render group and restarted the box. It looks like it allows hardware transcoding again. I tested playback via the web-client, and verified via checking the process call that channels-dvr was using ffmpeg with the -c:v h264_vaapi option. I'll keep an eye on it, and see if it reverts or not.

channels-dvr is running outside of a docker container. I tried to use the pre-built docker image, but was having some weird issues, so decided to just run it natively.