Public bug reported: TL;DR: When QEMU is launched with VNC as the output and viewed with a client that defaults to zlib VNC encoding, the resulting output tends to accumulate artifacts.
Reproduction: Launch QEMU (tried with versions 4.2.0 and 4.1.0 on Linux 64bit) with -vnc 0.0.0.0:0 Connect to it with a VNC client that allows you to select encoding, i.e. UltraVNC. Set encoding to zlib (type 6), 32bit color. As screen content changes it starts accumulating artifacts. Almost certain to appear if you open-close windows over a pattern. Does not seem to depend on guest used, but easier to reproduce with a GUI. Looks like this: https://orbides.org/img/vnc.png It appears to be a deflate glitch of some sort - all of the bad pixels are generated by length/distance codes. Can't narrow it down any more. ** Affects: qemu Importance: Undecided Status: New -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1858623 Title: VNC outputs garbage in zlib mode Status in QEMU: New Bug description: TL;DR: When QEMU is launched with VNC as the output and viewed with a client that defaults to zlib VNC encoding, the resulting output tends to accumulate artifacts. Reproduction: Launch QEMU (tried with versions 4.2.0 and 4.1.0 on Linux 64bit) with -vnc 0.0.0.0:0 Connect to it with a VNC client that allows you to select encoding, i.e. UltraVNC. Set encoding to zlib (type 6), 32bit color. As screen content changes it starts accumulating artifacts. Almost certain to appear if you open-close windows over a pattern. Does not seem to depend on guest used, but easier to reproduce with a GUI. Looks like this: https://orbides.org/img/vnc.png It appears to be a deflate glitch of some sort - all of the bad pixels are generated by length/distance codes. Can't narrow it down any more. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1858623/+subscriptions
