[Spice-devel] jpeg problem

[乱舞]

hi,all:
    When  I  transport images with jpeg in spice  to  reduce bandwidth.
i modify the spice-server   red_worker.c


worker->jpeg_state = SPICE_WAN_COMPRESSION_ALWAYS;
it worked, but caused some image visual problems,
if use jpeg ,there is a black rectangle In the upper left corner of lock screen(picture 1 inside the redline). 
and when i move the window there would be many black lines on the screen (picture 2)
when use glz ，quic,or lz4, There would not be such a problem. But when I use jpeg ,the bandwidth would be lower,so I need to solve the problem.
How to solve this problem ？ because of  lossy ? 
picture1

picture 2
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