The TRTC SDK provides the ability to send custom messages. With this feature, any user whose role is an anchor can broadcast their own custom messages to other users in the same video room.
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A user's custom message will be combined into the audio/video data streams and transmitted to other users in the same room alongside. As audio/video channels themselves are not completely reliable, in order to improve the reliability, the TRTC SDK implements a reliability guarantee mechanism internally.
Messages are sent by calling the sendCustomCmdMsg
API of TRTCCloud, and the following four parameters need to be specified during sending:
Parameter Name | Description |
---|---|
cmdID | Message ID. Value range: 1–10. Messages in different business types should use different cmdIDs . |
data | Message to be sent, which can contain up to 1 KB (1,000 bytes) of data. |
reliable | Whether reliable sending is enabled; if yes, the receiver needs to temporarily store the data of a certain period to wait for re-sending, which will cause certain delay. |
ordered | Whether orderly sending is enabled, i.e., whether the data should be received in the same order in which it is sent; if yes, the receiver needs to temporarily store and sort messages, which will cause certain delay. |
reliable
andordered
must be set to the same value (YES
orNO
) and cannot be set to different values currently.
// Sample code for sending a custom message
- (void)sendHello {
// Command word for the custom message. A set of rules needs to be customized according to the business needs. 0x1 is used as an example to send a text broadcast message
NSInteger cmdID = 0x1;
NSData *data = [@"Hello" dataUsingEncoding:NSUTF8StringEncoding];
// `reliable` and `ordered` need to be consistent for now. Orderly sending is used as an example here
[trtcCloud sendCustomCmdMsg:cmdID data:data reliable:YES ordered:YES];
}
// Sample code for sending a custom message
public void sendHello() {
try {
// Command word for the custom message. A set of rules needs to be customized according to the business needs. 0x1 is used as an example to send a text broadcast message
int cmdID = 0x1;
String hello = "Hello";
byte[] data = hello.getBytes("UTF-8");
// `reliable` and `ordered` need to be consistent for now. Orderly sending is used as an example here
trtcCloud.sendCustomCmdMsg(cmdID, data, true, true);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
// Sample code for sending a custom message
void sendHello()
{
// Command word for the custom message. A set of rules needs to be customized according to the business needs. 0x1 is used as an example to send a text broadcast message
uint32_t cmdID = 0x1;
uint8_t* data = { '1', '2', '3' };
uint32_t dataSize = 3; // Length of data
// `reliable` and `ordered` need to be consistent for now. Orderly sending is used as an example here
trtcCloud->sendCustomCmdMsg(cmdID, data, dataSize, true, true);
}
// Sample code for sending a custom message
private void sendHello()
{
// Command word for the custom message. A set of rules needs to be customized according to the business needs. 0x1 is used as an example to send a text broadcast message
uint cmdID = 0x1;
byte[] data = { '1', '2', '3' };
uint dataSize = 3; // Length of data
// `reliable` and `ordered` need to be consistent for now. Orderly sending is used as an example here
mTRTCCloud.sendCustomCmdMsg(cmdID, data, dataSize, true, true);
}
After a user in a room uses sendCustomCmdMsg
to send a custom message, other users in the room can receive the message through the onRecvCustomCmdMsg
API in the SDK callback.
// Receive and process messages sent by other users in the room
- (void)onRecvCustomCmdMsgUserId:(NSString *)userId cmdID:(NSInteger)cmdId seq:(UInt32)seq message:(NSData *)message
{
// Receive the message sent by `userId`
switch (cmdId) // `cmdId` agreed upon between sender and receiver
{
case 0:
// Process the message with `cmdId` = 0
break;
case 1:
// Process the message with `cmdId` = 1
break;
case 2:
// Process the message with `cmdId` = 2
break;
default:
break;
}
}
// Inherit `TRTCCloudListener` and implement the `onRecvCustomCmdMsg` method to receive and process messages sent by others in the room
public void onRecvCustomCmdMsg(String userId, int cmdId, int seq, byte[] message) {
// Receive the message sent by `userId`
switch (cmdId) // `cmdId` agreed upon between sender and receiver
{
case 0:
// Process the message with `cmdId` = 0
break;
case 1:
// Process the message with `cmdId` = 1
break;
case 2:
// Process the message with `cmdId` = 2
break;
default:
break;
}
// Receive and process messages sent by other users in the room
void TRTCCloudCallbackImpl::onRecvCustomCmdMsg(
const char* userId, int32_t cmdId, uint32_t seq, const uint8_t* msg, uint32_t msgSize)
{
// Receive the message sent by `userId`
switch (cmdId) // `cmdId` agreed upon between sender and receiver
{
case 0:
// Process the message with `cmdId` = 0
break;
case 1:
// Process the message with `cmdId` = 1
break;
case 2:
// Process the message with `cmdId` = 2
break;
default:
break;
}
}
// Receive and process messages sent by other users in the room
public void onRecvCustomCmdMsg(string userId, int cmdId, uint seq, byte[] msg, uint msgSize)
{
// Receive the message sent by `userId`
switch (cmdId) // `cmdId` agreed upon between sender and receiver
{
case 0:
// Process the message with `cmdId` = 0
break;
case 1:
// Process the message with `cmdId` = 1
break;
case 2:
// Process the message with `cmdId` = 2
break;
default:
break;
}
}
Since custom messages have a higher transmission priority than audio/video data, if too many of them are sent, audio/video data may be interfered with, resulting in video lagging or blurring. Therefore, the following frequency limits apply to custom messages:
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