Multiple video playback on two GPU


I’m trying to build system with two T1000 video cards, total 8 outputs in order to play 8 4K video files - one at each output. There were problems with configuring 8 separate screens and I tried to discuss it in another topic, but meantime I was able to build configuration with two screens each with four monitors.

Now I’m trying to play video file with mpv player.
If I start player for screen :0.0 it shows C+G process type for that player in nvidia-smi, but when I start second player for screen :0.1 it have spread processes across two GPU and it looks like NVDEC of only one (first) GPU is used here:

Is it possible to create configuration (hardware and software) in Linux so NVDEC of both cards will be used for playing video, so I will be able to start more simultaneous video?

Attached nvidia-bug-report output just for the case it may be useful here.
nvidia-bug-report.log.gz (1.8 MB)


Taking it from here:


Choose the GPU device used for decoding when using the cuda or nvdec hwdecs with the OpenGL GPU backend, and with the cuda-copy or nvdec-copy hwdecs in all cases.

For the OpenGL GPU backend, the default device used for decoding is the one being used to provide gpu output (and in the vast majority of cases, only one GPU will be present).

For the copy hwdecs, the default device will be the first device enumerated by the CUDA libraries - however that is done.

For the Vulkan GPU backend, decoding must always happen on the display device, and this option has no effect.

So maybe you can choose the gpu per command-line for each mpv instance.

This proposition looks promising.
Tried this:

but my 0.32.0 mpv complains that this option is not known (despite it present in man mpv documentation).

Will try to update my system to more recent version in order to have more fresh mpv.

So far tried vlc player and found that it use NVDEC of corresponding video card depending on which screen playback is started. So GPU memory usage and NVDEC engine usage is distributed evenly for both channels!