One 2 many audio streaming, via NodeJS or whatever

Question

For sometime now I've been trying to do something that I never thought that it would be that hard: audio streaming. My objective is simple; a simple web app through which a certain someone can click a button and live-stream his own voice to other people using this app. It's an online classroom of sorts. Here's the details:

• A broadcast/lecture is scheduled for a certain date and time (done)
• A user logs-in as a teacher/instructor to a simple interface where he can click "start broadcasting" (done)
• When the instructor clicks "broadcast" his voice is streamed to other users. Other student-type users can also log in and start listening to THE BROADCAST this teacher started. (and here is the trick!)
• The broadcast itself should be automatically stored to a local file in the process. So that students can go back to it anytime.

Of course I spent so many hours googling and stackoverflow-ing this problem, and here is what I could understand so far:

• If the starting point is the browser, I must use the GetUserMedia API, the result is raw PCM data that I can download, send to server or stream to others. (simple)
• Offering the broadcast to the listeners (students) will be done via HTML5's Audio API. (simple)
• WebRTC cannot help me here, because it's a p2p thing, there cannot be a server middling in the process, and I NEED TO KEEP A COPY OF THE LECTURE LOCALLY. (Here's a working example)
• I can use tools like Binary.js to stream the audio binary data to the students, but this requires a file to be present already on the desk.
• I need to convert the PCM data to a format like MP3 or OGG in the process, and not use WAV because it's much expensive bandwidth-wise.

I feel like it should be straight forward, but I cannot get it to work, I cannot piece all of this together and offer a stable and good experience for the user.

So again, I would love to know how to do the following:

Break the GetUserMedia raw data into packets and convert it to mp3, stream it to the server, where a script (NodJS probably) can store it locally and stream it whoever tuned-in, in real time.

I am open to whatever tool you recommend, I know that NodeJS will be present in the solution, and I am happy to use it. If the streaming could be done via a 3rd-party tool, I have no problem with that.

Thanks you in advance.

Answer 1

I see your comment about WebRTC, but I think you should investigate it more.

Like what you see here in this (old) post: http://servicelab.org/2013/07/24/streaming-audio-between-browsers-with-webrtc-and-webaudio/

Otherwise, you might have to go for a third party solution, like https://www.crowdcast.io/

(Even if you find a video-only solution, you can use a static picture or so for the video)

Event broadcasting is a good business for many companies. If it was that easy, there wouldn't be only few and well known competitors in the market.