How to obtain a feed of comments entered through the 'chat' box during a YouTube live broadcast?
The YouTube API enables users to obtain a comments feed, e.g. via https://gdata.youtube.com/feeds/api/videos/VIDEO_ID/comments?orderby=published.
However, when I try to do just that with the video ID of a live stream, the result is always empty, no matter how many comments have been submitted. The only difference between a live video and any other video (or recording of a live stream) is that the 'comments' section is replaced with a 'chat' box, whose comments seem not to be available via the API.
When the stream is stopped, all comments submitted through the chat box 'disappear' entirely and can no longer be accessed. However, all comments submitted after the live broadcast has been archived (i.e. the recording has been made available) show up in the comments feed.
For a real-time application I need to access the 'chat' comments while the broadcast is still live, to retrieve user-submitted questions.
Is there any way to do this?
Answer
It is now possible to return chat messages for your own broadcasts using the LiveChatMessages endpoint as part of the YouTube Live Streaming API.
When creating a new liveBroadcast object, a liveChatId String will be returned as part of that liveBroadcast's snippet. Pass your broadcast's chat ID to LiveChatMessages/list endpoint's liveChatId parameter, and id, snippet, and authorDetails into the part parameter.
HTTP GET https://www.googleapis.com/youtube/v3/liveChat/messages?liveChatId={liveChatId}&part=id%2C+snippet%2C+authorDetails&key={YOUR_API_KEY}
This will return an array of liveChatMessage resources. The actual chat message is contained in the textMessageDetails dictionary as the value for the messageText key.
"textMessageDetails": {
"messageText": string
}