[Webkit-unassigned] [Bug 85851] MediaStream API: support MediaStreamRecorder implementation

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed Jul 11 04:27:37 PDT 2018


Octavian Naicu <naicuoctavian at gmail.com> changed:

           What    |Removed                     |Added
                 CC|                            |naicuoctavian at gmail.com

--- Comment #10 from Octavian Naicu <naicuoctavian at gmail.com> ---
Having this feature in Safari on iOS would allow us to move away from the limited HTML Media Capture spec (which on Safari/iOS doesn't even work for audio just video) and implement proper video recording directly in iOS devices using our UI, our start/stop/pause controls, our constraints, JavaScript, we could trigger events, etc.

Having this feature in Safari on macOS would allow us to retire the last piece of Flash we're using.

(In reply to Jeremy Noring from comment #6)

> Roundabout story: we've tried to make a MediaRecorder polyfill with
> webassembly, and it is prohibitively difficult for a number of reasons
> (tl;dr codec royalties are a thing, javascript garbage collection and video
> are hard, script processor nodes are finicky and working with a canvas has
> some idiosyncrasies that are difficult to address).  

We've actually considered doing the same thing: taking snapshots from the canvas and encoding them as video using a WebAssembly video encoding library. I'm not sure it's possible though or, if works, if it could be used in production. For example these FFMPEG WebAssembly builds are 12MB in size and 4-5MB gzipped https://github.com/BrianJFeldman/ffmpeg.js.wasm. Another problem is audio would have to be captured separately and thus it will most certainly be out of sync.

As an example, there is a working MediaRecorder polyfill for audio that records uncompressed pcm in .wav https://github.com/ai/audio-recorder-polyfill

We've also tried using WebRTC to establish a p2p connection to a server and record the video server side but the video quality is bad (since WebRTC prioritizes low latency as it should) and the connection process is extremely complex (to account for all possible networks) resulting in failed connections: https://addpipe.com/blog/troubleshooting-webrtc-connection-issues/

Chrome supports mediastream recording since January 2016. It was "The most starred Chrome feature EVER" with 2877 stars https://developers.google.com/web/updates/2016/01/mediarecorder

I am not even that much concerned about codecs as we can easily convert those server side to whatever we need.

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