TeamTalk 5 C-API DLL Version 5.19A

Client Programming Guide

The following sections gives a step-by-step tour of building a user application which uses the TeamTalk C-API DLL to transmit voice and video. In order for the user application to interact with other clients a TeamTalk server must first be set up. Section TeamTalk Server Setup Guide explains how to do this.

The job of the TeamTalk server is to keep track of connected users and provide user autentication. Once a client is connected and has been authenticated the client is presented with a tree structure where each node is a so-called channel which the client can join and from there interact with the other users who are in the same channel.

The following six steps explains how to build a TeamTalk client:

- Step 1: Create a TeamTalk Client Instance
- Step 2: Initialize Sound and Video Devices
- Step 3: Connect to a TeamTalk Server
- Step 4: Log on to a TeamTalk Server
- Step 5: Join a channel on the TeamTalk Server
- Step 6: Transmit data to users in a Channel

# Step 1: Create a TeamTalk Client Instance

A new client instance is created by calling TT_InitTeamTalkPoll() which will return a TTInstance pointer to the new client instance. When the user application quits ensure to call TT_CloseTeamTalk() with the returned TTInstance so the client instance can close down properly.

Once a new client instance has been created its current state can always be retrieved by calling the function TT_GetFlags() which will return a bitmask describing the client's current state. Initially after creating the client instance a call to TT_GetFlags() will return a bitmask with the value CLIENT_CLOSED since no operations have been performed on the client.

# Step 2: Initialize Sound and Video Devices

Before connecting to a server it is a good idea to setup the user's sound and video devices. Sound devices are initialized using the TT_InitSoundInputDevice() and TT_InitSoundOutputDevice() functions. The video capture device is initialized using TT_InitVideoCaptureDevice(). Initializing the video capture device can be quite tricky because there's many properties which needs to be configured. Look at the SDK sample applications to see how it's done.

Once sound and video devices has been initialized the function TT_GetFlags() will return a mask containing CLIENT_SNDINPUT_READY, CLIENT_SNDOUTPUT_READY and CLIENT_VIDEOCAPTURE_READY.

# Step 3: Connect to a TeamTalk Server

Calling TT_Connect() will make the client connect to the server running on the IP-address and port numbers specified as parameters to the function. After this call the TT_GetFlags() function will have the CLIENT_CONNECTING bit set. TT_Connect() is a non-blocking call so the user application must query the client instance for events by calling TT_GetMessage() to see if a connection has been established.

If the TT_Connect() call fails the event CLIENTEVENT_CON_FAILED will be posted to the event queue and retrieved by TT_GetMessage() and the CLIENT_CONNECTING bit will be cleared.

If the TT_Connect() is successful the event CLIENTEVENT_CON_SUCCESS will be posted to the event queue and the CLIENT_CONNECTED bit will be set and CLIENT_CONNECTING will be cleared.

# Step 4: Log on to a TeamTalk Server

Once connected the user application can call TT_DoLogin() to log on to the server. All functions with the prefix TT_Do* are client to server commands (see Client/Server Commands). The TT_DoLogin() requires that the user application provides a username and password for a user account on the server.

TT_DoLogin() is also a non-blocking call so the client instance's message queue must be queried, using TT_GetMessage(), to see if the login was successful. If the server rejects the login the event CLIENTEVENT_CMD_ERROR is posted along with an error code (see ClientError).

If the server accepts the login information the CLIENTEVENT_CMD_SUCCESS event is posted and the the client instance will have the CLIENT_AUTHORIZED flag set.

For every channel on the server a CLIENTEVENT_CMD_CHANNEL_NEW event will be posted and a CLIENTEVENT_CMD_USER_LOGGEDIN will be posted for every user logged on to the server. The CLIENTEVENT_CMD_USER_JOINED event follows which tells if the user is in a channel.

# Step 5: Join a channel on the TeamTalk Server

Now that the client is connected and authorized it is possible to join a channel on the server. This is done by either calling the function TT_DoJoinChannel() to create a new channel or by calling TT_DoJoinChannelByID() to join an existing channel.

If using the TT_DoJoinChannelByID() command to join a channel the ID of the channel must be retrieved and also the password needed to join the channel. The ID of a channel is posted in the CLIENTEVENT_CMD_CHANNEL_NEW event and the password (if any) must be provided by the user.

If the call to TT_DoJoinChannelByID() is successful the event CLIENTEVENT_CMD_SUCCESS is posted and if the server rejected the command to join the CLIENTEVENT_CMD_ERROR event is posted.

# Step 6: Transmit data to users in a Channel

Having joined a channel now enables the client instance to start transmitting audio and video to the other users in the channel by calling TT_EnableVoiceTransmission() and TT_StartVideoCaptureTransmission().

When the other users in the channel starts receiving audio they will receive the CLIENTEVENT_USER_STATECHANGE event. If video is also being transmitted the event CLIENTEVENT_USER_VIDEOCAPTURE will be posted for every video frame which is received.