choppy playback with vlc

[thebobbyboy420]

default install of subgraph and im getting very choppy playback in vlc any ideas?

[dma]

This is critical. I've done some research into what's going on here, but it seems promising that we can fix it.

• HD videos in Chromium, FF running in xpra seem to work great.
• Not-even-HD videos played in xpra with vlc or mplayer are TERRIBLE.
• Over the last week or two we did extensive testing on the following theories and none of them tested the following and all of them were discounted:
  • Existing seccomp-bpf whitelists in SGOS installed in either mpv or vlc processes have no perceptible effect on video / audio performance in a non-xpra run
  • On modern laptops used by the SGOS team, the software only renderer + disabling hardware decoding support do not affect performance
  • Furthermore, tests were done where the video decoding/decompression alone with performed inside the sandbox (i.e. w/o access to hardware acceleration) with raw video/audio streamed to player outside sandbox. Video performance was excellent when there was sufficient read buffer (8MB was enough)

Current theory is that xpra is managing the rate of refresh, and not entering the right "mode" when video players are run. This would explain why browser videos work: xpra recognizes what is happening and adjusts. Cursory examination of xpra code revealed it has a lot of capability for this kind of thing, though documentation isn't great.

We are still looking into this and are pretty heavily committed to fixing it. The performance in SGOS today is totally unacceptable.