[Spice-devel] Information about video detection

[Yonit Halperin]

On 07/02/2013 10:22 AM, Matilde Yanez wrote:
>
> Hi,
> thanks for answers.
>
> 2013/7/2 Yonit Halperin <yhalperi at redhat.com <mailto:yhalperi at redhat.com>>
>
>     Hi,
>
>     On 07/01/2013 04:27 AM, Matilde Yanez wrote:
>
>         Hello,
>
>         I need some information about video detection, on VM.
>         When I am on web pages, or documents, with images the VM seems
>         to detect
>         video and start the mjpeg_encoder process.
>         Thus, the display is slows down.
>
>     What vm are you using? We encountered such behaviour with
>     gnome-shell, due to high frequency updates of regions over the
>     primary surface.
>
>
> On CentOs and Windows VMs, indeed with high frequency updates of regions
> it considers that is video. Such as large Excel documents or web page
> with many images. Adding log I can see that spice server starts stream,
> and does the same treatment as video.
Have you used the default setting of streaming-video 
(streaming-video=filter), or did you use streaming-video=on? Can you 
send me an example document and the Microsoft Office version you are using?
>
>         With argument streaming-video=off, the CPU consomation goes up.
>
>     This is unexpected. On which guest scenarios?
>
>
> When I play a movie, with default "streaming-video" arguments, on
> windows VM, I am around 60% of CPU consomation of VM's qemu process
> ("top" command), and with "streaming-video=off" I am around 120%.
> Due to all images that are send to refresh client display?
>
Ok, it is expected for movie playback. I thought you meant that it 
happens for the document browsing.
>         Increasing the value of "RED_STREAM_FRAMES_START___CONDITION",
>         does not
>         launch the video detection on these documents and keep fluidity on
>         videos and documents
>
>         How can i make difference between real video, and documents with
>         images?
>
>     I'm afraid there is no simple answer for this
>     (1) Why does the driver send frequent updates? Does the rectangles
>     that are being updated really change? Can it be prevented on the
>     driver side?
>     (2) If the area that is being refreshed doesn't change much, we can
>     apply a quick comparison of sampled regions of 2 successive
>     "frames", and if most of the pixels stay the same, we won't consider
>     those "frames" as part of a video stream. (for such scenarios we
>     would also like to improve and employ the GLZ encoding, or change
>     our caching mechanism, to be applied on slices of bitmaps)
>
>
> I think I will investigate on the 2nd point.
>
>            On what part of the spice-server code can i make changes?
>
>     Code that is related to video streams is located in red_worker.c, in
>     routines with "stream|upgrade" in their names.
>
>
>         Thanks,
>         Matilde.
>
>     Regards,
>     Yonit.
>
>
> Matilde.
>
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>