Can I connect to multiple audio input devices using MediaDevices.getUserMedia() for a webrtc stream?

Question

I haven't found any support for this in the getUserMedia docs. If I can only request a single audio device via constraints, I'm wondering if it's possible to call getUserMedia again for the second audio device, then merge/combine the resulting streams into one so I can attach it to a single audio/video element.

My end goal is to set up a webrtc stream that consists of video and 2 audio input devices. I already have a webrtc stream setup with video and a single audio input device working, I am just looking to merge in an additional audio stream. I mention this in case there is some option for this on the webrtc side as well.

With all of that said, if there is a solution for combining streams, will there be a concern for keeping the audio in sync?

Thanks in advance!

Brian Brian · Accepted Answer · 2020-05-23T10:13:20

So I ended up creating this function to accomplish the stream merging:

function createMergedStream(...streams: MediaStream[]): MediaStream {
    const audioContext = new AudioContext()

    const audioSources: MediaStreamAudioSourceNode[] = []
    const videoTracks: MediaStreamTrack[] = []

    streams.forEach((stream) => {
        stream.getTracks().forEach((track) => {
            if (track.kind === "video") {
                videoTracks.push(track)
            }
        })
        audioSources.push(audioContext.createMediaStreamSource(stream))
    })

    const destination = audioContext["createMediaStreamDestination"]()
    audioSources.forEach((audioSource) => {
        audioSource.connect(destination)
    })

    videoTracks.forEach((track) => {
        destination.stream.addTrack(track)
    })

    return destination.stream
}

Turns out the client was actually looking to access multiple channels from a multi-channel audio interface, so I have some more digging to do. Figured I'd shared this code regardless, in case someone ever stumbles across this post.

Can I connect to multiple audio input devices using MediaDevices.getUserMedia() for a webrtc stream?

3 Answers