Overview
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.
How It Works
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.
Sending Messages
Messages are sent by calling the sendCustomCmdMsg API of TRTCCloud, and the following four parameters need to be specified during sending:
|
| Message ID. Value range: 1–10. Messages in different business types should use different cmdIDs. |
| Message to be sent, which can contain up to 1 KB (1,000 bytes) of data. |
| 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. |
| 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. |
Note:
reliable and ordered must be set to the same value (YES or NO) and cannot be set to different values currently.
- (void)sendHello {
NSInteger cmdID = 0x1;
NSData *data = [@"Hello" dataUsingEncoding:NSUTF8StringEncoding];
[trtcCloud sendCustomCmdMsg:cmdID data:data reliable:YES ordered:YES];
}
public void sendHello() {
try {
int cmdID = 0x1;
String hello = "Hello";
byte[] data = hello.getBytes("UTF-8");
trtcCloud.sendCustomCmdMsg(cmdID, data, true, true);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
void sendHello()
{
uint32_t cmdID = 0x1;
uint8_t* data = { '1', '2', '3' };
uint32_t dataSize = 3;
trtcCloud->sendCustomCmdMsg(cmdID, data, dataSize, true, true);
}
private void sendHello()
{
uint cmdID = 0x1;
byte[] data = { '1', '2', '3' };
uint dataSize = 3;
mTRTCCloud.sendCustomCmdMsg(cmdID, data, dataSize, true, true);
}
try {
int cmdId = 0x1;
String hello = "hello";
_trtcCloud.sendCustomCmdMsg(cmdId, hello, true, true);
} catch (e) {
print(e);
}
const trtc = TRTC.create();
await trtc.enterRoom({ sdkAppId, userId, userSig, roomId: 12345 })
const data = new TextEncoder().encode('hello').buffer;
trtc.sendCustomMessage({ cmdId: 1, data });
Receiving Messages
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.
- (void)onRecvCustomCmdMsgUserId:(NSString *)userId cmdID:(NSInteger)cmdId seq:(UInt32)seq message:(NSData *)message
{
switch (cmdId)
{
case 0:
break;
case 1:
break;
case 2:
break;
default:
break;
}
}
public void onRecvCustomCmdMsg(String userId, int cmdId, int seq, byte[] message) {
switch (cmdId)
{
case 0:
break;
case 1:
break;
case 2:
break;
default:
break;
}
void TRTCCloudCallbackImpl::onRecvCustomCmdMsg(
const char* userId, int32_t cmdId, uint32_t seq, const uint8_t* msg, uint32_t msgSize)
{
switch (cmdId)
{
case 0:
break;
case 1:
break;
case 2:
break;
default:
break;
}
}
public void onRecvCustomCmdMsg(string userId, int cmdId, uint seq, byte[] msg, uint msgSize)
{
switch (cmdId)
{
case 0:
break;
case 1:
break;
case 2:
break;
default:
break;
}
}
TRTCCloudListener(
onRecvCustomCmdMsg: (userId, cmdId, seq, message) {
},
onMissCustomCmdMsg: (userId, cmdId, errCode, missed) {
}
);
trtc.on(TRTC.EVENT.CUSTOM_MESSAGE, event => {
console.log(`received custom msg from ${event.userId}, message: ${new TextDecoder().decode(event.data)}`)
})
Use Limits
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:
As custom messages are broadcast to all users in the same room, up to 30 messages can be sent per second.
A data packet (i.e., data size) can be of up to 1 KB; if the threshold is exceeded, the packet is very likely to be discarded by the intermediate router or server.
A client can send up to 8 KB of data in total per second, that is, if each data packet is of 1 KB, up to 8 packets can be sent per second.
