Posted: Thu Jun 08, 2006 12:46 pm Post subject: [Asterisk-video] H320
Hi Ian,
I've been thinking about doing the same. From what I can see it's quite
do'able. The main protocols that would be needed are H.221, H.231, H.242
and H.243. Then you might want to add H.281 for FECC I guess... Then
there's the issue of the various bonding methods but I'm a bit out of
date with ISDN VC so maybe that's not an issue anymore.
I'm not sure if it's been discussed before but I've mentioned it a
couple of times on the various email lists.
The issue for us is: what's the usage likely to be. There's lots of
H.320 being used at the moment but a lot is moving to IP. It might make
some sense if there was video conferencing support in Asterisk and it
could act as a bridge and gateway, but I'm not sure what demand there
would be.
Has anyone any views on the sort of demand there might be for H.320
support on Asterisk?
Posted: Thu Jun 08, 2006 2:29 pm Post subject: [Asterisk-video] H320
Hi John
Quote:
Has anyone any views on the sort of demand there might be for H.320
support on Asterisk?
I would most definitely be interested in Asterisk supporting this.. We
currently have a number of clients using ISDN conferencing, but would like
to move to IP based handsets...
If Asterisk could act as the bridge, it would be an incredibly useful tool
:-)
--
Tom Paseka
IT Operations
T3 Communications
T: 1300 655 657
F: 1300 655 659
tomas.paseka@t3.net.au
Level 6, 97 Pacific highway
North Sydney, NSW 2060
http://www.t3.net.au
Posted: Thu Jun 08, 2006 9:42 pm Post subject: [Asterisk-video] H320
Olle E Johansson wrote:
Quote:
8 jun 2006 kl. 22.40 skrev Ian Esper:
> I was thinking the possibility to incoporate H320 in asterisk, what
> are the possibilities on doing that? Was it discussed before?
>
Can you please explain a bit more? Why H320 - what's the application?
If I recall correctly, H320 was the protocol for ISDN videoconferencing.
It's a bit tricky to implement since you can use more than one B channel for the same call (bonding).
The H320 videoconference kits are (or used to be) very expensive, but the quality of the video was great also. For that I think that many companies are still using it and don't plan to change it in the near future.
So it could be great to have it integrated into asterisk, so we could offer a full IP(SIP,H323)-ISDN(H320)-UMTS(H324M) gateway. And make everything work with meetme conferences :)
Greetings
Sergio
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Posted: Thu Jun 08, 2006 10:14 pm Post subject: [Asterisk-video] H320
Quote:
So it could be great to have it integrated into asterisk, so we could offer
a full IP(SIP,H323)-ISDN(H320)-UMTS(H324M) gateway. And make everything
work with meetme conferences :)
Posted: Thu Jun 08, 2006 10:26 pm Post subject: [Asterisk-video] H320
9 jun 2006 kl. 09.14 skrev [T3] Tom Paseka:
Quote:
> So it could be great to have it integrated into asterisk, so we
> could offer
> a full IP(SIP,H323)-ISDN(H320)-UMTS(H324M) gateway. And make
> everything
> work with meetme conferences :)
I'd kill for that!!
To be a bit more civilized ;-)
- Does anyone want to contribute funding for development
of this?
- Does anyone have development resources that can create this solution?
To be a bit more technical:
- How much do we need to change libpri?
- How much do we need to change zaptel?
- How much do we need to change the PBX core?
- How do we transcode to SIP phones?
And legal:
- Are there any patents standing in the way?
Posted: Thu Jun 08, 2006 11:17 pm Post subject: [Asterisk-video] H320
Quote:
To be a bit more civilized ;-)
- Does anyone want to contribute funding for development of this?
- Does anyone have development resources that can create this
solution?
I'm currently making some development on the H324m part, but I still have to discuss internally the license and if we can open source what I'm doing.
Quote:
To be a bit more technical:
- How much do we need to change libpri?
- How much do we need to change zaptel?
- How much do we need to change the PBX core?
- How do we transcode to SIP phones?
I think H324M and H320 would have simillar issues. First we would need to change libpri/zaptel in order to allow changing the q931 to support more types of call than just speech ones.
I also found that it could be interesting to change the default frame size for reading from b channels.
The integration with the pbx core should be done in an application which behaves simillar to the dial one, for example, accepting one channel in h324m/h320 negotiate the protocol, dial another channel (with video support) and brige them.
And we would need some transcoding capabilities, or at least some "transrating" capabilities.
Greetings
Sergio
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You must not, directly or indirectly, use, disclose, distribute, print, or copy any
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Posted: Thu Jun 08, 2006 11:24 pm Post subject: [Asterisk-video] H320
Quote:
>
>> So it could be great to have it integrated into asterisk, so we
>> could offer
>> a full IP(SIP,H323)-ISDN(H320)-UMTS(H324M) gateway. And make
>> everything
>> work with meetme conferences :)
>
> I'd kill for that!!
>
To be a bit more civilized ;-)
- Does anyone want to contribute funding for development
of this?
We would be more interested in doing the work than funding it. We could
provide some elements of what is already needed and might look for a
royalty per system, like G.729 is done, because of that. If there were
enough funding then we could forgo the royalty.
Quote:
- Does anyone have development resources that can create this solution?
If there were enough funding, we could do this.
Quote:
To be a bit more technical:
- How much do we need to change libpri?
Clear data channels would need to be presented to the chan_h320. This
may already be available. Don't forget chan_misdn as another means of
getting at ISDN.
Quote:
- How much do we need to change zaptel?
Clear data channels would need to be presented to the chan_h320. This
may already be available.
Quote:
- How much do we need to change the PBX core?
There shouldn't be too much needed here. All the resynchronisation of
the multiple B channels is handled in the bonding code.
Quote:
- How do we transcode to SIP phones?
The same way that H.323 does... we sync/source G.7xx frames and H.26x
frames. Any H.320 code would have to concern itself with padding of the
B-channels up to the total bandwidth needed, and to strip padding from
the H.320 media streams to provide a variable bitrate stream for SIP and
H.323. It gets a bit messy when the SIP or H.323 burst over their
allowed bandwidth (as some do), but on the whole that should be
manageable.
Quote:
And legal:
- Are there any patents standing in the way?
Not to my knowledge. There's still the usual H.263 issue but as long as
we're not actually encoding then that wouldn't apply.
/O_______________________________________________
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Posted: Thu Jun 08, 2006 11:43 pm Post subject: [Asterisk-video] H320
Good point. I was wondering this on the way into work this morning. I'm
not sure how a lump of code that provided H.320 would be able to be used
in both PRI and BRI channels, or if it's an app, func, channel or res?
It brings up an interesting point about things like SIP, IAX and H.323
they all use IP as the transport but have their own channel drivers
rather than a common IP channel driver and an app/func/res... just an
observation. So things that are IP based can have their own channel
drivers but ISDN based things can't :-)
-----Original Message-----
From: asterisk-video-bounces@lists.digium.com
[mailto:asterisk-video-bounces@lists.digium.com] On Behalf Of Olle E
Johansson
Sent: 09 June 2006 09:37
To: Development discussion of video media support in Asterisk
Subject: Re: [Asterisk-video] H320
Quote:
> To be a bit more technical:
> - How much do we need to change libpri?
Clear data channels would need to be presented to the chan_h320. This
You say "chan_h320" - is it a separate channel really? Isn't it just
another way
of using the zap/misdn channels?
Otherwise, I would assume a lot of replicated code - or?
/O
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Posted: Thu Jun 08, 2006 11:49 pm Post subject: [Asterisk-video] H320
9 jun 2006 kl. 10.43 skrev John Martin:
Quote:
Good point. I was wondering this on the way into work this morning.
I'm
not sure how a lump of code that provided H.320 would be able to be
used
in both PRI and BRI channels, or if it's an app, func, channel or res?
It brings up an interesting point about things like SIP, IAX and H.323
they all use IP as the transport but have their own channel drivers
rather than a common IP channel driver and an app/func/res... just an
observation. So things that are IP based can have their own channel
drivers but ISDN based things can't :-)
Well, I was just a bit curious. It's not obviously a new channel seen
with eyes from someone who does not know the details. Is the signalling
very much different on an ISDN video call than an audio call?
Unfortunately the API for MISDN and ZAP channels are very different.
For IAX2, SIP and H.323 the signalling is *very* different. Do remember
though that SIP, H.323 and MGCP all share the RTP driver :-)
Posted: Fri Jun 09, 2006 12:11 am Post subject: [Asterisk-video] H320
Olle E Johansson wrote:
Quote:
9 jun 2006 kl. 10.43 skrev John Martin:
> Good point. I was wondering this on the way into work this morning.
> I'm not sure how a lump of code that provided H.320 would be able to
> be used in both PRI and BRI channels, or if it's an app, func,
> channel or res?
>
> It brings up an interesting point about things like SIP, IAX and
> H.323 they all use IP as the transport but have their own channel
> drivers rather than a common IP channel driver and an
> app/func/res... just an observation. So things that are IP based can
> have their own channel drivers but ISDN based things can't :-)
Well, I was just a bit curious. It's not obviously a new channel seen
with eyes from someone who does not know the details. Is the
signalling very much different on an ISDN video call than an audio
call?
Unfortunately the API for MISDN and ZAP channels are very different.
For IAX2, SIP and H.323 the signalling is *very* different. Do
remember though that SIP, H.323 and MGCP all share the RTP driver :-)
AFAIK, H324M and H320 just open a b channel of type Unrestricted digital information (instead of the Speech that it's the one that asterisk does), and on top of that channels it starts negotiating the protocol.
So having the isdn channel abstracted is a good thing as you don't need to handle the all the isdn internalls.
All we need is an isdn channel that offer a clean digital channel and does the correct q931 negotiation.
The idea of the application (for incomming calls for example) I have is one like this:
So you've got an isdn channel in the application with h324m, in which you start the h324m negotiation.
You read from the channel pass it to the h324m code and viceversa. Once you have the call stablished, dial the sip peer and start reading the audio and video from the channle and passing it as input to the h324 which will mux it and send it to the isdn part, and continue reading from the isdn channel demuxing it and passing the audio/video to the sip channel.
Probably in H320 is a bit more tricky if you are going to do bonding
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You must not, directly or indirectly, use, disclose, distribute, print, or copy any
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Posted: Fri Jun 09, 2006 12:18 am Post subject: [Asterisk-video] H320
9 jun 2006 kl. 11.11 skrev Sergio Garc?a Murillo:
Quote:
Olle E Johansson wrote:
> 9 jun 2006 kl. 10.43 skrev John Martin:
>
>> Good point. I was wondering this on the way into work this morning.
>> I'm not sure how a lump of code that provided H.320 would be able to
>> be used in both PRI and BRI channels, or if it's an app, func,
>> channel or res?
>>
>> It brings up an interesting point about things like SIP, IAX and
>> H.323 they all use IP as the transport but have their own channel
>> drivers rather than a common IP channel driver and an
>> app/func/res... just an observation. So things that are IP based can
>> have their own channel drivers but ISDN based things can't :-)
>
> Well, I was just a bit curious. It's not obviously a new channel seen
> with eyes from someone who does not know the details. Is the
> signalling very much different on an ISDN video call than an audio
> call?
>
> Unfortunately the API for MISDN and ZAP channels are very different.
>
> For IAX2, SIP and H.323 the signalling is *very* different. Do
> remember though that SIP, H.323 and MGCP all share the RTP driver :-)
>
AFAIK, H324M and H320 just open a b channel of type Unrestricted
digital information (instead of the Speech that it's the one that
asterisk does), and on top of that channels it starts negotiating
the protocol.
So having the isdn channel abstracted is a good thing as you don't
need to handle the all the isdn internalls.
All we need is an isdn channel that offer a clean digital channel
and does the correct q931 negotiation.
Which is done in chan_zap - or?
Quote:
The idea of the application (for incomming calls for example) I
have is one like this:
exten => s,1,Answer
exten => s,2,H324MTransfer(SIP/blablabla)
Why not use dial?
Quote:
So you've got an isdn channel in the application with h324m, in
which you start the h324m negotiation.
Which may belong in the channel driver...
Quote:
You read from the channel pass it to the h324m code and viceversa.
Once you have the call stablished, dial the sip peer and start
reading the audio and video from the channle and passing it as
input to the h324 which will mux it and send it to the isdn part,
and continue reading from the isdn channel demuxing it and passing
the audio/video to the sip channel.
But we can't establish a call until we know we have something in the
other end that can accept it.
We might have to send the call to voicemail or forward it somewhere
else before we answer or simply not answer at all, because
no one is available... We don't want to re-implement app_dial, it's
already been done once... ;-)
Quote:
Probably in H320 is a bit more tricky if you are going to do bonding
Sorry for all the propably stupid questions, but it is important that
we follow the current design
of Asterisk as much as possible. I am very afraid of adding another
layer on top.
Posted: Fri Jun 09, 2006 12:28 am Post subject: [Asterisk-video] H320
Hi Olle,
I see there's been some follow up posts while I was writing this, but
here's my input...
Like the IP standards H.320 is a layered protocol. So you can think of
ISDN being like IP and H.320 being like SIP/H.323. In fact for every
protocol you find in H.323 (H.245, H.225, Q.931) there's an equivalent
in H.320 (H.241, H.221, Q.931 plus others).
The H.320 is encapsulated in the B-channels, whereas with SIP and H.323
the protocols are encapsulated in IP packets. So the call control is
basic ISDN with different bearer types in the Q.931 setup etc. Once the
calls are up the H.320 protocols worry about how to align the channels
and negotiate capabilities etc. To take the comparison a bit further:
the call being spread across multiple B-channels is like trying to take
the RTP in a SIP call and de-mulitplex every RTP packet into n packets
(where n=8: RTP byte 0 goes to packet0[0], RTP byte 1 goes to
packet1[0]... RTP byte 8 goes to packet0[1] etc), and then send the n
packets in parallel - with the commensurate differing delays between the
n parallel streams that have to be re-synchronised when they reach their
destination. This scheme is very similar to the way that GSM does stuff
like HSCSD.
One way to think of H.320 would be as the video protocol for ISDN, so
in that sense it could be included into libpri/zaptel. But then you've
got to add it to mISDN and they'd have to share the same code, but, as
you say, with different API's :-(
-----Original Message-----
From: asterisk-video-bounces@lists.digium.com
[mailto:asterisk-video-bounces@lists.digium.com] On Behalf Of Olle E
Johansson
Sent: 09 June 2006 09:50
To: Development discussion of video media support in Asterisk
Subject: Re: [Asterisk-video] H320
9 jun 2006 kl. 10.43 skrev John Martin:
Quote:
Good point. I was wondering this on the way into work this morning.
I'm
not sure how a lump of code that provided H.320 would be able to be
used
in both PRI and BRI channels, or if it's an app, func, channel or res?
It brings up an interesting point about things like SIP, IAX and H.323
they all use IP as the transport but have their own channel drivers
rather than a common IP channel driver and an app/func/res... just an
observation. So things that are IP based can have their own channel
drivers but ISDN based things can't :-)
Well, I was just a bit curious. It's not obviously a new channel seen
with eyes from someone who does not know the details. Is the signalling
very much different on an ISDN video call than an audio call?
Unfortunately the API for MISDN and ZAP channels are very different.
For IAX2, SIP and H.323 the signalling is *very* different. Do remember
though that SIP, H.323 and MGCP all share the RTP driver :-)
/O
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