Re: MPCS? and source code discussion (semi-long)

Scott Lacroix (
Wed, 22 Jul 1998 17:35:36 -0400

Sheesh, stop reading for a couple days and my name ends up in somebody's
message.... :)

At 06:20 AM 7/21/98 -0500, Jason Williams wrote:
>On Tue, 21 Jul 1998, david morel wrote:
>> Question, who knows the scoop of the actual use of
>> h.323 with MPCS?
>Depends on what you mean by "scoop" :)
>> I downloaded the dreaded 3.x to play around with this,
>> from the 3.x machine I could see the netmeeting machine
>> without troubles, but the 3.x client was not even in my list of
>> connected users in netmeeting.
>The 3.X client has to use the H.263 codec (and for audio, the G.723
>codec). If the 3.X client doesn't use the H.263 codec, they can't be seen
>on Netmeeting. The other troublesome fact is Netmeeting users can never
>really tell who the CU participants are. The way I got around that is by
>forcing the required video codec (pref-vid-codec command) to H.263,
>forcing the required audio codec (pref-aud-codec command) to G.723, and
>not allowing any lurkers. This means anyone that can show up will show up
>to all participants involved. It's STILL a big hassle though because CU
>users can chat amongst themselves and H.323 users can chat amongst
>themselves (assuming the T.120 server is running), but they can't chat
>with CU users. CU users can't chat with Netmeeting users either. There's
>no crossover between CU and Netmeeting with chat like there is with video
>and audio. Whenever I played with it, I also had to set the MPCS server
>up to switch vid based on a time delay rather than the default of audio
>switching. What that means is it will switch who is in the vid every X
>seconds rather than whoever used audio last. It works, but it's far from
>complete. As I understand it, V.CHAT (or something like that), is the
>standard for chat that's arising.

All that is pretty accurate... Although it was T.CHAT the last time I
checked, and that was awhile ago. Could be different now... but watch
NetMeeting 'cuz it seems that everyone else is. ;)

>> If I connect with 2.x , I can see the connection made, but netmeeting
>> says not sharing... and 2.x does NOT see the netmeeting. (that part was
>> half what I expected) I believe the MPCS docs state that one should be
>> able to see other h.323 clients, but would have to use the t.120
>> server for chat.
>2.X users (as far as I know) can't be seen by Netmeeting unless they use
>the H.263 codec. I'm not even sure 2.X users can see other H.323 clients.
>Scott at White Pine has told me there's a lot of work going into letting

>people have the ability to use the 2.X versions with the H.263 codec to
>talk to other H.323 clients. I've never seen it done.

Same as all other clients, no-one can be seen by NetMeeting (or any other
H.323 client) unless they are sending a codec that client can see. H.263 is
the one that gets installed by CU-SeeMe 3.1.X.X so if you use that, it
should work.
If you install an H.263 video codec on your machine, your 2.X client should
auto-magically pick it up and DECODE that video stream. I THINK there are a
few public H.263 decoders out there... but I have no idea where. I guess
you could do a web-search and see what you can find.
Also, if you install 3.1.X on your machine, and you ALREADY HAVE 2.X you
should be able to RECIEVE H.263 vid with a 2.X client using the H.263 codec
decoder that comes with 3.1.X. It doesn't look like there is any way to
SEND anything but the basic three codecs (MJPG, SFMC, and Grey) however.
So... there's no work being done per-se. It should just work. The caveat
is that you can't send any codec from a 2.1 client that an H.323 client can
see. Same problem as the Cornell client(s).

Just a friendly update :)

- Scott


,,-==================================-.-==================================-.. | I haven't lost my mind, it's backed | Scott LaCroix ( | | up on tape around here somewhere... | Sr. Software Engineer ___ | | - Author Unknown | White Pine Software ./_ -\. | | #include<disclaimer/std.h> | q| o O |p | ``-==================================-^-=====================oOOo=~U~=oOOo-''