How does the Gizmocall work - analysis of the mechanism

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These days, I analyzed the Gizmocall carefully. Finally, I got something about it's working mechanism.

We knew that until now there's no APIs released by Adobe for voip, so we can not program directly. While in order to implement voip function, we have to implement sip, rtp, codec/decode etc.

There're two ways to do that,
1, to implement those functions with the ActiveScript. You can create a swc file to include all the things, thus the swf can call the functions imported from the swc file.
Currently, I know that the Ribbit phone had their own swc lib. I think the Gizmocall should not use that one, anyway, the gizmocall is another leader in this field. They should have their own technical. Otherwise the gizmocall-plugin can not be explained.

2, to use a nother plugin to implement all the things related to the voip.
Gizmocall had a plugin named, gizmocall-plugin. After you installed the app, you can find a GizmoPlugin demo running in the background from the task list. I think it's the core role in their implementation.

We can find some thing about the plugin on the gizmocall website. They said that the plugin is responsible for the code/decode. But I think it's not so simple.  It should have some more responsiblities.

Let's think about a question, how can they exchange infomation between the flash player and the local system?

We know that the ActiveScript can use the shared object to communicate with local system. But it's clear it's not possible to use it to share the rtp data:). So the plugin should not use this method to exchange data.
Is there another way? Yes, there do be another way!
Socket:) The latest falsh player v9 support bin socket. That's the key:)
The plugin use the socket to exchange data with local system.
OK, now that the media data can be exchanged, why can not the signaling data?

I think the answer is positive! The plugin can use the socket to exchange signaling data with the flash player.
Thus all the sip, rtp, codes can be dealed with in the plugin, while the swf running in the flash player only deal with GUI. That's very clear and simple way to implement the voip function with the flash player:)

Anyway, it's a voip implementation based on the flash!

clever guys do the clever thing:)