[Qemu-devel] Re: [PATCH v2 03/10] vnc: only use a single zlib stream

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 05/18/2010 08:52 AM, Alexander Graf wrote:
> Anthony Liguori wrote:
>    
>> On 05/18/2010 07:51 AM, Alexander Graf wrote:
>>      
>>> Corentin Chary wrote:
>>>
>>>        
>>>> According to http://tigervnc.org/cgi-bin/rfbproto#zlib-encoding
>>>> zlib encoding only uses a single stream. Current implementation defines
>>>> 4 streams but only uses the first one. Remove them and only use a
>>>> single
>>>> stream.
>>>>
>>>>
>>>>          
>>> How about when we start to implement zrle or zhextile? Wouldn't those
>>> need different streams?
>>>
>>>        
>> Only tight uses multiple streams.  zrle just uses one.
>>      
> Ah, that's why I put it in there back then. I see :).
>    

Keep in mind, tight's 4 streams are not the same as zrle or zlib's 1 
stream.  A server is free to send both Tight updates and zrle updates if 
the client supports it.  The client is going to expect that zrle is a 
different compression stream than any of the 4 tight streams.

That's why you can't use the Tight compression level selection messages 
to choose the zlib compression level btw.

Regards,

Anthony Liguori

> Alex
>
>