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cpearce's comments

cpearce | 4 years ago | on: HTMLMediaElement.canPlayType()

Back in the day, I worked on this API in Firefox.

It's a very old API that was speced before promises were a thing. Once you ship an API, sites start using it, and if you change behavior, you break them. If your browser ships the behavior change first, and breaks a website, people just assume your browser is the one that's broken, and switch browser. So browsers don't like to change behavior, especially before other browsers have, or if other browsers won't.

At least in Firefox's case, it's hard to be confident that the decoders we use for H.264 (the most commonly used codec at the time) would support a given mime type.

Firefox uses the operating system's H.264 decoders, because we had a policy of not feeding the patent trolls. H.264 has a plethora of different levels, profiles and features [1]. The documentation for operating system's H.264 decoders often isn't very clear as to what profiles/levels/features they support. Sometimes the user has installed codec packs which affect what codecs are playable. Sometimes the user is on Windows K/N which ships without H.264 codecs. So the only way to give an accurate answer to the question, is to actually start up Windows Media Foundation, and run some video through them. This requires loading DLLs from disk, and obviously we don't want to be blocking on disk IO in the browser's JS event loop in order to accurately answer this question, and we might not have an example file for the specific combination of profile/level/features the script was asking about. In the end, we ended up doing a "test decode" on startup of the common profiles and caching the result in the user's profile. But again, if the user asks about an obscure profile or level combination we've not tried, we can't necessarily be confident that we'll actually be able to play this.

Saying "yes" optimistically and being wrong would be bad, as then the player would appear to be broken in your browser, leading users to switch browser. So the idea was script would try a few profile/level/feature combinations and pick the best to which the browser returned yes.

We probably could have done a more accurate job here if we had more time, but it's always a trade off between marginal benefits here, verses fixing something else.

[1] https://blog.pearce.org.nz/2013/11/what-does-h264avc1-codecs...

cpearce | 5 years ago | on: Wireless Is a Trap

I have the TP-Link AV2000 and found them good. My office has a bunch of metal laundry appliances and concrete walls between my desk and the wifi router, so wifi signal is terrible there. Solved it with the AV2000.

I also tried using a mesh wifi network, and was able to bounce a signal around the dead zone and get a WiFi signal with a higher bandwidth than the powerline ethernet, but I still found I got a lot of glitches in video calls, so went back to the powerline ethernet.

I've not noticed the problems other commenters here had with their adapters with the AV2000.

I initially tried a cheaper powerline ethernet, and it was worse than WiFi, so I'd recommend you buy the most expensive/best one that you can afford.

cpearce | 5 years ago | on: New 13-inch MacBook Pro

Dear Apple... I will pay $200 extra for the option of a keyboard with physical function keys and no touchbar.

Sincerely, Disappointed Customer.

cpearce | 13 years ago | on: H.264 Support Lands in Firefox 20 Nightly on Windows

It depends. You'll get better integration into the browser if you transcode. But if you're doing the "YouTube testcase", just using a Flash player fallback (without transcoding) would probably suit your needs adequately.

cpearce | 13 years ago | on: BigScreen — Javascript library for HTML5 Fullscreen API

Your video fallback behaviour seems superfluous. If you want fullscreen on a video, why don't you just request fullscreen on the video rather than its container?

Having the fullscreen request shift to the descendent video also breaks the case where you actually have an element containing a video that you want to make fullscreen, for example if you have custom controls for your video element... This is simply impossible with your API.

cpearce | 14 years ago | on: Hey CS Paper writers, please show your code

This won't fly in the real world. If an academic writer includes a link to their code in their paper, when it goes through peer review before being published, it will no longer under be a blind review; the reviewer will know who wrote the code by virtue of the github account or domain it's uploaded to. Blind reviews are important, as if you know you're reviewing a paper by someone who rejected your paper, you're more inclined to reject it. That really happens, people are that petty.

Additionally there's the risk that the reviewer will reject the paper, and download the code and publish a paper about it quickly in some other journal/conference.

cpearce | 14 years ago | on: HTML5 Map of the the World Migrations using SVG, Raphael.js and offline storage

No, you need to have units on your data. Without units, numbers mean nothing. You select a country, and then you're presented with a list of other countries and some numbers. It's not clear that these are lifetime immigrants or permanent residents. There should be a title on the country info box "Total lifetime immigrants" or "Total lifetime emigrants", and ideally a legend at the bottom defining what that means.

It's also confusing in that the number format follows a European convention of using decimal points rather than commas in between every three digits the numbers, though I can accept that localising your site isn't a big concern.

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