[Qemu-devel] Re: [PATCH 2/5] vnc: JPEG should be disabled if the client don't set tight quality

[Alexander Graf]

On 04.06.2010, at 15:19, Anthony Liguori wrote:

> On 06/04/2010 08:16 AM, Alexander Graf wrote:
>> On 04.06.2010, at 15:18, Corentin Chary wrote:
>> 
>>   
>>> Disable JPEG compression by default and only enable it if the
>>> VNC client has sent the requested quality.
>>> 
>>> Signed-off-by: Corentin Chary<address@hidden>
>>> ---
>>> vnc.c |    2 +-
>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>> 
>>> diff --git a/vnc.c b/vnc.c
>>> index ed0e096..9cf38d1 100644
>>> --- a/vnc.c
>>> +++ b/vnc.c
>>> @@ -1644,7 +1644,7 @@ static void set_encodings(VncState *vs, int32_t 
>>> *encodings, size_t n_encodings)
>>>     vs->features = 0;
>>>     vs->vnc_encoding = 0;
>>>     vs->tight_compression = 9;
>>> -    vs->tight_quality = 9;
>>> +    vs->tight_quality = -1; /* Lossless by default */
>>>     
>> So what's the threshold? When do you start to be lossy?
>>   
> 
> When the client explicitly requests it.

The tight quality level is a slider on most clients. A user doesn't know when 
it starts being lossy. He also can only choose 0 as the lowest (iirc). And IIRC 
the X tightvnc client also always sent the quality level.

Alex