Since my last post, quite a few new people have joined our group, a lot has changed in our implementation, and we’ve achieved a few things worth writing about. I also can’t keep these demos under wraps any longer, so it’s time for another post.
One of the first pieces of advice I got in the bug, when I started writing this patch to expose audio data in Firefox, was to use Vlad’s new typed arrays (aka WebGL Arrays). My first implementation used an array-like object to expose the audio data, and JS arrays for writing samples. Both worked well, but neither was as fast as we’d like, and it meant various hacks to work around performance issues. Vlad was kind enough to give me a crash course on how to implement them via quickstubs, and over the past few weeks, Yury Delendik and I have worked long hours to rewrite our entire implementation to use them.
In order to do this he had to overcome some interesting problems, for example, how to load large binary voice databases into the page. The straightforward approach of using a JS array was brittle, with JS sometimes running out of stack space trying to initialize the array. After trying various obvious ways, Yury decided to use the web to his advantage, and pushed the binary data into a PNG, then loaded it into a canvas, where getImageData allows him to access the bytes very quickly, using another typed array. The browser takes care of downloading and re-inflating the data automatically. Here’s what the database looks like:
What began as a series of experiments by a small group of strangers, has now turned into something much larger. Our community continues to grow, and the scope and scale of the projects being done on our API is increasing. At the same time, through the work of Doug Schepers and Chris Blizzard, we’ve managed to get the attention of the W3C, which have now started an Audio Incubator Working Group to look at how to standardize this stuff. One of my colleagues in these experiments, Al MacDonald, has been asked to chair the group, which already has members from Mozilla, Google, and the BBC. You can get involved and follow @AudioXG for updates.
If you’d like to stay connected to this work, you can join this bug, where I’ll be posting a patch for review in the next week or so (current patch is here). You can see our Audio Data API documentation, with tutorials and examples (this was recently completely rewritten, if you’ve looked at it before). You can also grab builds there, which I’m making right now and will be done in the next few hours.