Conversational AI of Tencent RTC provides the capability to display real-time subtitles. The real-time subtitles are sent through custom messages of Tencent RTC, enabling millisecond-level synchronization with the conversation audio.
You can use the Receive Custom Messages feature provided by the RTC Engine SDK to listen to callbacks in the client to receive data of real-time AI conversation subtitles. The cmdID value is fixed at 1. Features
1. Real-time synchronization: Subtitles are synchronized with the conversation audio with a millisecond-level latency.
2. Flexibility: The custom message format is used to facilitate integration and expansion.
Message Format
Real-time subtitle messages are in JSON format. Specific fields are as follows:
|
type | Number | Message type. 10000 indicates real-time subtitles. |
sender | String | User ID of the sender. |
receiver | Array | List of receivers' user IDs. The message is actually broadcasted in the room. |
payload | Object | Message payload. It contains the detailed subtitle information. |
The payload object contains the following fields:
|
text | String | Original text recognized by ASR（STT）. |
start_time | String | Start time of a sentence. Format: "HH:MM:SS". |
end_time | String | End time of a sentence. Format: "HH:MM:SS". |
roundid | String | Unique ID that identifies a conversation round. |
end | Boolean | If the value is true, the sentence is a complete one. |
Example Message
{
"type": 10000,
"sender": "user_a",
"receiver": [],
"payload": {
"text": "Hello. Nice to meet you."
"start_time": "00:00:01",
"end_time": "00:00:03",
"roundid": "conversation_123456",
"end": true
}
}
Implementation Notes
1. Message processing: Receivers need to correctly parse the JSON message and recognize real-time subtitles based on the type field.
2. Time synchronization: You can use start_time and end_time to ensure the subtitles are properly synchronized with the audio.
3. Conversation segmentation: You can use the end field to determine if a sentence is finished. This can be used for subtitle display or complete conversation storage.
Parsing a Custom Message with the Web SDK
trtcClient.on(Tencent RTC.EVENT.CUSTOM_MESSAGE, (event) => {
let data = new TextDecoder().decode(event.data);
let jsonData = JSON.parse(data);
console.log(`receive custom msg from ${event.userId} cmdId: ${event.cmdId} seq: ${event.seq} data: ${data}`);
if (jsonData.type == 10000 && jsonData.payload.end == false) {
} else if (jsonData.type == 10000 && jsonData.payload.end == true) {
}
});