[Asterisk-video] confbridge, h264 and switching

[Matthew Jordan]

Sergio,

If you have to retrieve information from the RTP packet and make some
decision based on information within that packet - regardless of whether
or not you have to fully decode the h.264 information contained within
that packet - that's more then Asterisk currently does.

There's a trade-off between performance and capability here, and
performing logic on information in the media streams can quickly impact
performance, particularly when you can't define the system your
application will run on.

That being said, this is a scenario that - in our testing - most SIP
clients handle quite well with a request to update the picture.  If
that's the only issue Dmitry is running into, its most likely best
handled by the client, or determining why Asterisk is not sending
the necessary SIP INFO message.

If someone requires full media mixing, they're more then welcome to
look at other products.

Matthew Jordan
Digium, Inc. | Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org

----- Original Message -----
> From: "Sergio Garcia Murillo" <sergio.garcia at fontventa.com>
> To: asterisk-video at lists.digium.com
> Sent: Monday, April 9, 2012 10:15:08 AM
> Subject: Re: [Asterisk-video] confbridge, h264 and switching
> 
> Hi,
> 
> I/P frame information can be retrieved from the h263/h264 stream
> without
> decoding it.
> 
> Anyway, if you wan to try a full Multiconference server to integrate
> with Asterisk, you can try mine.. ;)
> 
> http://www.medooze.com/products/mcu.aspx
> 
> Best regards
> Sergio
> 
> El 09/04/2012 16:34, Matthew Jordan escribió:
> >
> > ----- Original Message -----
> >> From: "Dmitry Melekhov"<dm at belkam.com>
> >> To: asterisk-video at lists.digium.com
> >> Sent: Sunday, April 8, 2012 10:55:53 PM
> >> Subject: Re: [Asterisk-video] confbridge, h264 and switching
> >>
> >> 06.04.2012 17:53, Matthew Jordan написал:
> >>> Dmitry:
> >>>
> >>> Can you explain what you mean by "it brokes during switching"?
> >> Hello!
> >>
> >> I mean that without i-frame talking user appears from squares and
> >> other
> >> strange shape still showing part of previous talker.
> > <snip>
> >
> > Okay, now I understand what you're referring to.
> >
> > Yes, if the client that has been made the new video source does not
> > transmit an I-Frame when they are made the video source, the
> > receiving
> > clients will predict their frames on the previously received frames
> > from the previous video source.  That would lead to what you're
> > describing.
> >
> > Since Asterisk does not interpret or decode the video streams it
> > receives from the clients, it does not have a mechanism itself to
> > manipulate the image.  It does, however, notify the client that is
> > the new video source via a SIP INFO message that it is now the
> > source
> > of the video.  It is up to the client to know that it should then
> > send
> > an I-Frame to provide a reference point for the other clients for
> > the
> > new video images.
> >
> > A few questions then:
> > 1. What clients are you using?  Do they support RFC 5168 (XML
> > Schema
> > for Media Control)?
> > 2. If you get a SIP trace or a packet capture, do you see Asterisk
> > sending the SIP INFO messages when a video update occurs?
> >
> > Thanks
> >
> > Matthew Jordan
> > Digium, Inc. | Software Developer
> > 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
> > Check us out at: http://digium.com&  http://asterisk.org
> >
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