[Spice-devel] Streaming video command line

Tue May 3 11:31:27 PDT 2011

Hi,
I have gathered other questions about spice and how it handles streaming
video. I think you can help me:

1)File red_worker.c.
I would like to have more information about these members of the struct
RedWorker :

   - RedSurface surfaces[NUM_SURFACES],
   - Ring current_list,
   - _Drawable drawables[NUM_DRAWABLES];
   - Stream streams_buf[NUM_STREAMS];

2)Function red_worker_main(), what does *red_handle_streams_timout()* do?

3)When you run qemu with option *-streaming_video=off* for example, the
function *spice_server_set_streaming_video() *in reds.c, calls *
red_dispatcher_on_sv_change(). *
**In this function there is a while loop on RedDispatcher *now. Dispatcher
is created in red_dispatcher_init_function, that it's called later, in this
way *now *is NULL and it doesn't enter in the while loop. As a consequence
of this,  *red_dispatcher_on_sv_change() *doesn't send
*RED_WORKER_MESSAGE_SET_STREAMING_VIDEO
*message.

Did I make myself clear?
Thanks very much.

2011/4/21 Alon Levy <alevy at redhat.com>

> On Thu, Apr 21, 2011 at 10:22:15AM +0200, Andrea Celestino wrote:
> > Thanks.
> > Now I am trying to study the code I am interested in.
> > Unfortunately, the file red_worker.c is very huge and there are not any
> > comments that can help me.
> >
> > I would like to know:
> > 1- which parts/functions of red_worker.c are video related stuff?
> A lot. Seriously - this requires a little more checking then I can give you
> off
> the top of my head. Questions 2 and 3 are more specific, so easier to
> answer.
> I would seriously suggest trying systemtap or just adding some prints to
> see
> what is going on. Start from red_process_drawable.
>
> > 2- You said:
> >  "determine if a given draw operation (has to be an opaque copy iirc) is
> >  repeated to the same area."
> > What do you mean with "opaque copy iirc"?
>
> iirc - if I recall correctly, meaning I'm not sure.
> opaque copy - an operation that copies a bitmap to a surface. The video
> streaming
> is done based on seeing repeated operations that copy a bitmap to the same
> surface, always surface 0 (that is the primary surface, we ignore repeated
> copies
> to non primary surfaces).
> opaque - meaning the destination bits are overwritten by the source bits,
> no binary
> operation is done (xor/and/or).
>
> >
> > 3- There are a red worker thread for each QXL device instance. How many
> QXL
> > device instance are there?
>
> One per device. But you can ignore the support for multiple devices for
> this,
> so just one if you run a single device ("-vga qxl").
>
> > 4- Which function does red_worker.c use to detect video streaming?
> >
> interesting functions are:
> __red_is_next_stream_frame
> anything with ->stream
> red_attach_stream
> anything with mjpeg
> red_current_add, the bottom part (that checks for OPAQUE and calls
> red_use_stream_trace)
>
> > Thanks for any helps you can give me
> Sure, please take a look at the above points and try what I suggested.
>
> Alon
>
> >
> > 2011/4/15 Alon Levy <alevy at redhat.com>
> >
> > > On Thu, Apr 14, 2011 at 03:20:40PM +0200, Andrea Celestino wrote:
> > > > I would like to improve the streaming video performance in Spice, do
> you
> > > > think that is possible to improve it? In what way?
> > > > Are there documents that describes in detail how spice works with
> video?
> > >
> > > The best I can offer in terms of documentation is the pdfs in the
> documents
> > > section of spice-space.org, I imagine you are looking for something
> more,
> > > sorry to disappoint.
> > >
> > > The code you are interested in is server/red_worker.c, but that's not
> very
> > > helpful since that file is huge. Would be nice to split the video
> related
> > > stuff to a separate file.
> > >
> > > worker->streaming_video - determines how we handle streaming video
> > >
> > > git grep stream -- server/red_worker.c
> > >
> > > I can give you better pointers if you ask more specific questions, but
> > > doing
> > > the documentation myself right now.. too much work.
> > >
> > > overview of what spice does:
> > >  * determine if a given draw operation (has to be an opaque copy iirc)
> is
> > >  repeated to the same area.
> > >  * if so, starts a mjpeg encoder and sends the stream to the client
> > >
> > > how to improve this (some is on the Features page in spice-space):
> > >  * learn to do various video acceleration apis (windows has it, linux
> has
> > > it)
> > >  * this is by far the best way to go regarding performance, unless you
> are
> > >  willing to sacrifice cpu for bandwidth in which case I guess you would
> > > reencode.
> > >  * otoh this is a pretty large change to multiple parts of spice:
> > >   * you need to update the driver for each platform you choose to
> support,
> > > update the protocol, teach server and client
> > >  * it's definitely on the todo list, but no date set.
> > >  * replace mjpeg with a different encoder
> > >  * if it's just a better performing encoder, clear win.
> > >  * otherwise you get the usual cpu/bw tradeoff.
> > >  * or you could try to learn which encoder fits which stream (based on
> some
> > >  metric, could be the performance of the encoders themselves)
> > >   * just throwing an idea.
> > >
> > > Alon
> > >
> > > >
> > > > 2011/4/11 Alon Levy <alevy at redhat.com>
> > > >
> > > > > On Mon, Apr 11, 2011 at 03:48:08PM +0200, Andrea Celestino wrote:
> > > > > > Hi,
> > > > > > I have installed Spice and now I'm trying to use it. I'm
> interested
> > > in
> > > > > how
> > > > > > spice manage streaming video. I read that there is the option
> > > > > >
> > > > > > -streaming-video=[all|off|filter]
> > > > > >
> > > > > > Can you explain me the difference between these three option?
> > > > > > Which source file read the command line?
> > > > > > Why I have tried to play a video in a player but i have not
> notice
> > > any
> > > > > > difference between the two options 'off' and 'filter'?
> > > > > >
> > > > >
> > > > > Look at
> > > http://cgit.freedesktop.org/spice/spice/tree/server/red_worker.c
> > > > >
> > > > > search for STREAM_VIDEO_FILTER
> > > > >
> > > > > The switch toggles modes for creating streams:
> > > > >  off - never create
> > > > >  all/filter - create either based on smallest size, or just based
> on
> > > > >  number of consecutive opaque copies to same area.
> > > > >
> > > > > > Thanks very much for the help.
> > > > >
> > > > > > _______________________________________________
> > > > > > Spice-devel mailing list
> > > > > > Spice-devel at lists.freedesktop.org
> > > > > > http://lists.freedesktop.org/mailman/listinfo/spice-devel
> > > > >
> > > > >
> > >
> > > > _______________________________________________
> > > > Spice-devel mailing list
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> > > > http://lists.freedesktop.org/mailman/listinfo/spice-devel
> > >
> > >
>
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