[Spice-devel] [spice] Enable mm_time adjustments on startup

[Frediano Ziglio]

> 
> On Thu, 11 Apr 2019, Victor Toso wrote:
> 
> > Hi,
> > 
> > On Wed, Apr 10, 2019 at 11:25:17AM +0200, Francois Gouget wrote:
> > > We send mm_time adjustments to the client whenever there is no audio
> > > playback. There is no audio playback on startup. Therefore
> > > mm_time_enabled must be true on startup. QED.
> > > 
> > > Signed-off-by: Francois Gouget <fgouget at codeweavers.com>
> > 
> > But what are you trying to fix/improve exactly?
> 
> The goal is to reduce the video stream latency.
> 
> The reason for that is that while a minimum 400 ms latency is fine when
> playing a YouTube video [1], it's very annoying when the whole desktop
> is being streamed, either through the streaming agent or through the
> future Virgl remote access, because then it translates into a 400 ms
> lag between every mouse click, keypress and the screen update.
> 
> This patch is the first step in that without it adjusting the latency is
> impossible unless one has played some sound first.
> 

Honestly I would remove this weird 400ms latency altogether.
This would remove also the clock bouncing back and forth based on sound.
IMHO client(s) should handle their latency on their own.

> Other steps are:
> * Reducing the default latency.
> * Increasing the latency when needed.
> * Reducing the latency after network hiccups.
> * Ensuring latency adjustments don't interfere with the video stream bit
>   rate control.
> 
> 
> [1] Even in that case the 400 ms latency shows up as the hiccup you get
>     when Spice switches from sending frames as regular screen updates to
>     the streaming code.
> 

Frediano