[Spice-devel] Image Compression.

Yonit Halperin yhalperi at redhat.com
Sun Sep 18 05:11:07 PDT 2011

On 09/16/2011 11:21 PM, Naga Mohan Pothula wrote:
> Hi,
> Could anyone please respond to my questions on Image Compression?
> Comparision of auto_glz with Quic?
> why auto_glz is taken as default?
Both GLZ and QUIC are lossless compression algorithms.
Quic uses predictive encoding, while GLZ is dictionary-based.
As such, Quic compresses better picture-like images, while GLZ is better 
with images with patterns.
auto_glz means that for each image we heuristically choose the 
compression method (GLZ vs. Quic) according to some sampling of the pixels.

> I did setup Dual head environment with Xinerama for RHEL6 guest.
> Refreshing of Web Pages/Windows doesn't happen at fast when we
> drag/scroll down windows and it is clearly noticeable on 24'' Large
> monitors.
> Looks like Bitmap delivering process to client needs to be improved.
Indeed. See some plans in http://spice-space.org/page/EnhancePerf

> Is Image Compression doesn't work properly due to Xinerama enabled?
> Appreciated your help in advance.
> Thanks,
> Mohan.
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