OK, so I went into the BIOS settings for the machine, and the only
options for the video configuration is to set video switching to either
dynamic or fixed. Dynamic (which was selected) allows the system to
switch between the video card "on demand", while fixed (which is now
selected) requires the OS or the user to manually switch between video
cards.
After setting the video configuration to fixed, I booted into Ubuntu and
retried the mpv test with your video. I noticed only one brief lag (too
fast to even let me try doing top or dmesg). Here is the output from
mpv, which shows only a single dropped frame (which would be unnoticable
for most people watching a video):
tracy@tracy-hp:/mnt/VM$ mpv bbb_sunflower_1080p_60fps_normal.mp4
Playing: bbb_sunflower_1080p_60fps_normal.mp4
(+) Video --vid=1 (*) (h264 1920x1080 60.000fps)
(+) Audio --aid=1 --alang=und (*) (mp3 2ch 48000Hz)
Audio --aid=2 --alang=und (*) (ac3 6ch 48000Hz)
File tags:
Artist: Blender Foundation 2008, Janus Bager Kristensen 2013
Comment: Creative Commons Attribution 3.0 - http://bbb3d.renderfarming.net
Composer: Sacha Goedegebure
Genre: Animation
Title: Big Buck Bunny, Sunflower version
AO: [pulse] 48000Hz stereo 2ch s16
Using hardware decoding (vaapi).
VO: [opengl] 1920x1080 vaapi[nv12]
AV: 00:10:34 / 00:10:34 (100%) A-V: 0.000 Dropped: 1
Exiting... (End of file)
tracy@tracy-hp:/mnt/VM$
So, at this point, it looks like the dynamic switching was the basic
problem. However, of interest to me is why this didn't present in
earlier versions (I have run 16.04, 17.04, and 17.10 (Wayland), none of
which exhibited this problem).
So, given this, is there something specific that you want in the way of
system information, or are we going to write this off to a (relatively
minor) BIOS incompatibility with something introduced in 18.04? (I can
live with the manual switching, at this point, if that's what it comes
down to...)
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https://bugs.launchpad.net/bugs/1774915
Title:
Video lag when using totem (audio does not lag)
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