Bug#881489: playback scaled to 4k fullscreen is choppy

[Daniel Pocock]

On 12/11/17 17:43, Sebastian Ramacher wrote:
> Control: tags -1 + moreinfo
> 
> On 2017-11-12 11:23:24, Daniel Pocock wrote:
>> Package: vlc
>> Version: 2.2.6-1~deb9u1
>>
>>
>> Trying to play a video file with a resolution 720x526, 25fps, MPEG-1/2
>> (problem also observed with other videos at different resolutions)
>>
>> With the window maximized and the option "Always Fit Window" selected,
>> it appears to zoom to 3:1 and playback appears good.
>>
>> When fullscreen is selected (up to the 4k resolution of the display), I
>> frequently see what appears to be a horizontal tear across the middle of
>> the picture, especially when there is a lot of movement in the video.
>>
>> Using mpv 0.23.0-2+b2 at fullscreen with the same video I don't observe
>> the problem.
>>
>> I don't have libvdpau1 installed due to problems with the frame rate[1]
>>
>> Hardware is Intel i3-7100U CPU @ 2.40GHz and Kaby Lake integrated
>> graphics Intel HD Graphics 620 (Kabylake GT2)
> 
> Please provide the output of vlc -vvv. Did you try selecting different video
> output modules (e.g. the OpenGL one)?
> 

I had a look at the preferences window, video tab.  The "Output" option
was automatic.

Looking at the logs, I notice it was selecting xcb_xv (XVideo)


[00007f3a54001268] xcb vout display debug: connected to X11.0 server
[00007f3a54001268] xcb vout display debug:  vendor : The X.Org Foundation
[00007f3a54001268] xcb vout display debug:  version: 11902000
[00007f3a54001268] xcb vout display debug: using screen 0xf5
[00007f3a54001268] xcb_xv vout display debug: using XVideo extension v2.2
[00007f3a54001268] xcb_xv vout display debug: using adaptor Intel(R)
Textured Video
[00007f3a54001268] xcb_xv vout display debug: using port 74
[00007f3a54001268] xcb_xv vout display debug: using image format 0x30323449
[00007f3a54001268] xcb_xv vout display debug: using X11 visual ID 0x20
(depth: 24)
[00007f3a54001268] xcb_xv vout display debug: using X11 window 0x03200000
[00007f3a54001268] xcb_xv vout display debug: using X11 graphic context
0x03200002
[00007f3a54001268] core vout display debug: VoutDisplayEvent 'fullscreen' 0
[00007f3a54001268] core vout display debug: VoutDisplayEvent 'resize'
3840x2017 window
[00007f3a54001268] core vout display debug: using vout display module
"xcb_xv"






I manually changed it to "OpenGL GLX video output (XCB)" and the problem
goes away.



[00007f10c8001268] core vout display debug: using vout display module
"xcb_glx"




Looking at the mpv logs as well, it appears to be using OpenGL by default:



[vo/opengl] Initializing OpenGL backend 'wayland'
[vo/opengl/wayland] failed to connect to a wayland server: check if a
wayland compositor is running
[vo/opengl] Initializing OpenGL backend 'x11probe'
[vo/opengl/x11] X11 opening display: :1
[vo/opengl/x11] X11 running at 3840x2160 (":1" => local display)
[vo/opengl/x11] Detected wm supports NetWM.
[vo/opengl/x11] Detected wm supports FULLSCREEN state.
[vo/opengl/x11] Detected wm supports ABOVE state.
[vo/opengl/x11] Detected wm supports BELOW state.
[vo/opengl/x11] Display 0 (DP1): [0, 0, 3840, 2160] @ 30.000000 FPS
...
[vf] Video filter chain:
[vf]   [in] 720x576 [64:45] yuv420p bt.601/bt.601-625/bt.1886/limited
CL=mpeg2/4/h264
[vf]   [out] 720x576 [64:45] yuv420p bt.601/bt.601-625/bt.1886/limited
CL=mpeg2/4/h264
[cplayer] VO: [opengl] 720x576 => 1024x576 yuv420p
[cplayer] VO: Description: Extended OpenGL Renderer


Is there any other detail I should look for in the log?

Should the automatic setting use a different default?

Regards,

Daniel