[Spice-devel] we need help about video problem！！！

[Victor Toso]

Hi,

On Tue, Jul 10, 2018 at 08:25:50PM +0800, molo wrote:
> hi,
>    I am sorry to trouble you！

Don't be!

>    We encountered the problem of video picture jam in the
>    process of using the spice protocol, and the audio and video
>    out of sync problem also appeared in the drag and drop
>    player window. When trying to solve the problem, we changed
>    the encoding method from mjpeg to h264, but the problem
>    didn't seem to improve. After that we tried to encode with
>    hardware, but it failed. It seems that kvm can't access
>    NVIDIA's device driver.

So many questions!
- Are you using spice's server h264 encoding without any extra
  patch/changes, is that correct? In that case, spice-server
  (host) does software encoding with x264enc [0] [1]

[0] https://gitlab.freedesktop.org/spice/spice/blob/master/server/gstreamer-encoder.c#L892
[1] https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-ugly-plugins/html/gst-plugins-ugly-plugins-x264enc.html

As far as I know that's software encoding. It may works well with
NVDIA, etc, but I haven't tested... but notice again that this is
in the host machine.

>    Two question as follows：
>    1、I want to confirm whether kvm can access the hardware
>       driver and perform hardware coding？

If x264enc can do it, yes. Otherwise you would need to implement
something around nvenc [2] or some generic pipelines that try to
use hardware encoding by default (on client, we use playbin)

[2] https://bugzilla.gnome.org/show_bug.cgi?id=753405

>    2、Have you ever encountered video jams, audio and video out
>    of sync? How to solve it? Wouldn't it be better to decode on
>    the client side via hardware?
>    
>     spice-protocol：0.12.14 release
>     client:our  software based spice-gtk(0.35 release)  
>     spice-server:0.14 release
> 
> 
> Hope that I will receive your reply soon。ths！

Not all replied but something to kick in discussion,
cheers

        toso
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