November 23, 2016
A really enhanced webcam stream!
Recently, HTMLCanvasElement.captureStream() was implemented in browsers. This allows you to expose the contents of a HTML5 canvas as a MediaStream to be consumed by applications. This is the same base MediaStream type that getUserMedia returns, which is what websites use to get access to your webcam.
The first question that comes to mind is, of course: “Is it possible to intercept calls to getUserMedia, get a hold of the webcam MediaStream, enhance it by rendering it into a canvas and doing some post-processing, then transparently returning the canvas’ MediaStream?”
As it turns out, the answer is (more…)
November 2, 2016
This article is a re-post of one that I wrote on the Telenor Blog earlier this year. It explains how MediaStreams work in Firefox and the changes I did to them to accommodate cloning.
First of all. What is a MediaStreamTrack, and how can you clone it?
A MediaStreamTrack represents a realtime stream of audio or video data.
It provides a common API to the multiple producers (getUserMedia, WebAudio, Canvas, etc.) and consumers (WebRTC, WebAudio, MediaRecorder, etc.) of MediaStreamTracks.
A MediaStream is simply put a grouping of MediaStreamTracks. A MediaStream also ensures that all tracks contained in it stay synchronized to each other, for instance when it gets played out in a media element.
Cloning a track means that you get a new MediaStreamTrack instance representing the same data as the original, but where the identifier is unique (consumers don’t know it’s a clone) and disabling and stopping works independently across the original and all its clones.
Now, how does all this come together in Firefox? (more…)