Cam Scam
British TV runs at 25 frames per second. American TV, for some bizarre historical reason, is at 29.97fps. Films at the cinema are at 24fps - which means frames need to be dropped or "interpolated" to be shown on TV.
The highest quality video produced for the internet is at 30fps, though 15 is more common. Youtube and similar services generally run at 12. Occasionally you'll find 10 or 5.
If you want to put video on the net, I'd say it needs to be at a minimum of 12fps, which means if you're filming on a webcam, it needs at least that frame speed.
No problem, most webcams can run up to 30fps. Yeah, right. The advertisements say they do, the technical specifications on the websites say they do - and perhaps on super-duper-computer connected by firewire, they would. But on a merely good computer connected by USB, they don't.
No problem, just spend as much money as you can on your webcam, and as well as the better lenses, you'll get something closer to the top speed, right? Well, no.
I've got four cheap webcams in this room. They are:
* A Logitech E3500, which cost me GBP26 last month, but which is now rather infuriatingly sold for GBP12.
* A Canyon CNR-WCAM413, which cost my dear mother GBP13 two years ago.
* A PCLine cam, which cost GBP15
* A BisonCam, built into this laptop. It obviously doesn't have a seperate price tag, but the miniaturisation must push up the price of the laptop.
The BisonCam manages 7fps - no good for filming anything except timelapse nature photography, and barely adequate for videoconferencing. Though it's actually the best in low light conditions.
The PCLine cam gives a horribly muddy image, is manufactured by a company who don't even mention it on their own website, has drivers that are almost impossible to find...and manages 8fps. It's advertised as 30 and I hate everything about it.
The Logitech gives lovely clear images thanks to its superior lenses, and clocks in at 5fps, despite the claim on the box to run at 30. Occasionally I've managed to get it up to 6.
The Canyon gives good images and, wait for it, 25 frames per second. Though all the websites say 30.
So, the oldest and cheapest of my webcams is also the best. Or rather, its official specifications are the least untruthful. And it isn't actually mine.
The most expensive sold locally is GBP85 and supposedly clocks in at...30fps. I wonder if it actually does.
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You've got all those webcams... and I've never seen your face.
ReplyDeleteWebcams creep me out. What if the gov't is using it to spy on me while I sleep or eat!
ReplyDelete@David:
ReplyDeleteIndeed. Secrets become more difficult to reveal the longer they're kept, even when there was never an especially good reason for keeping them in the first place.
@Eroswings:
You know how headphones can in principle be used as microphone? Well I've taken that one step further. I spy on the government through my webcam :-).
One day I'll have cybersex with the MI5.
Just be sure to take precautions! You don't want to catch a virus from unprotected cybersex!
ReplyDeleteOne day I'll have cybersex with the MI5.
ReplyDeleteWhilst singing “Why Don’t We Do it in the Road?”
This article is an overview of the various frame rates. Of course, it says nothing about the marketing weasels's lies about the web cams.
ReplyDeleteOh Hai MJ!
@XL: Ah yes, it goes into some of the details I glossed over, in particular interlacing.
ReplyDeleteOdd that it doesn't mention the 25i of PAL.
I hadn't previously come across the 72p rate.