[Spice-devel] Trouble with lossy compression

[Pavel Grunt]

Hi!

On Sun, 2016-07-10 at 23:00 -0300, Adriano Moura wrote:
> I've been trying to use a virtual machine over wi-fi but I'm having trouble
> activating the lossy compression method in spice. I can reach about 50mbps but
> that does not cut with lossless compression while playing a video. I've tried
> all command switches for qemu related to spice compression methods, but no
> such luck. Here is an excerpt of the machine's xml config:
> 
>   <graphics type='spice' autoport='yes' listen='0.0.0.0'>
>     <listen type='address' address='0.0.0.0'/>
>   </graphics>
> [...]
>   <qemu:commandline>
>     <qemu:arg value='-spice'/>
>     <qemu:arg value='image-compression=auto-glz,streaming-video=all,jpeg-wan-
> compression=always,zlib-glz-wan-compression=auto,playback-compression=on'/>
>   </qemu:commandline>

Better to use XML nodes for spice arguments as Christophe said.
> 
> Tried different values and checked if qemu's process is carrying those
> arguments. (it did)
> 
> Very occasionally the spice connection will start with lossy compression
> enabled (as if it's actually honoring my settings), but as soon as I
> reconnect, it falls back to lossless.
> 
> I'm running an updated ArchLinux install. Here are some packages that may be
> of interest:
> 
> community/libvirt-glib 0.2.3-1
> extra/spice 0.12.7-1
> extra/spice-protocol 0.12.11-1
> community/spice-glib 0.32-1
> community/spice-gtk3 0.32-2
> extra/qemu 2.6.0-1
> core/linux 4.6.3-1
> 
> Tried with multiple clients: spicy, remote-viewer, aSPICE (android) and
> vinagre
> 
> The VM was generated with virt-viewer/libvirtd
> 
> Any tip would be welcome!

Spice can change the image compression on the fly, you can use:
virt-viewer --spice-preferred-compression=... (see virt-viewer --help-spice)

also spicy has a menu for changing image compression under "Options"

Pavel

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