nvfbc cuda regression: picture does not update

[Antoine Martin]

Problem spotted on win32, may also affect Linux (TBC).

The code runs and it looks like we're downloading the frames from video memory, but when scrolling detection runs it finds that the picture has not changed and so we end up not generating any screen updates.

Forcing scrolling detection off does not help: the video encoders also find the picture unchanged. This also applies to the NVENC encoder when using the picture data found in the CUDA buffer which would indicate that the API is just not capturing new data. (rather than a download / usage problem on our side)
This could be a driver bug, or a problem with the API uncovered by newer drivers.

Related tickets:

• #365 keep buffer on GPU
• #1317 NVFBC
• #1597 GPU buffer processing

[Antoine Martin]

r18299: CUDA buffer mode no longer enabled by default

TODO:

• check linux (move graphics cards around... sigh)
• fix + backports if needed
• also backport r18300?

[Antoine Martin]

• win32 fixed in r19103: we no longer push + pop the cuda context and just keep it live until we close it
• r19104 re-enables cuda by default

[Antoine Martin]

Linux was not affected.

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/1763