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I want to produce ultrasonic sound from an iPhone device.
How can I do that?
At least the iPhone 4s is rated for 20Hz - 20,000Hz, which means it cannot generate ultrasonic frequencies.
I doubt that any mass-market iOS device will produce ultrasonic frequencies.
http://www.apple.com/iphone/iphone-4/specs.html
I know of no cellphones with ultrasonic transducers as standard. The small speaker on most phones may well have some response at ultrasonic frequencies, but the D>A converters and audio amplifiers will not.
You need special hardware.
Create the sound on your computer (http://www.blackcatsystems.com/software/audiotoolbox.html maybe?), store it as a WAV (or any other compatible format) and play it back using the audio playback capabilities on iOS.
EDIT
OK, so the phone itself can't do it.
Build some custom hardware that can emit sound waves at frequencies higher than 20,000Hz and then develop an application to utilise the hardware.
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I am on a search for ultra accurate gps for iOS development. CoreLocations best is still 10 metres off most times, and jumps about. Within the commercial bounds of iOS development, is this defiantly the very best accuracy we have? Any work arounds? Interested to know how close to perfection i can get it.
I know this is not a normal code question, but it's relevant and will help many others too.
Unfortunately 10 meters is an ideal accuracy for iPhone. In real it may be even worse. If you are developing some kind of fitness application take a look at Kalman filter. It allows to get pretty accurate track on iPhone data.
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I have 3 heos speakers in my house and a 4th wireless (wifi) speaker that I built myself. I was wondering if anyone else has tried tinkering around with the heos app to make it detect other wifi speakers and play music to them?
I tried using dlna to get my logitech/squeeze boxes and heos speakers to play the same music, which worked but there was a significant delay between the two systems that I couldn't correct with the squeezebox software settings.
Right now the only way to hook up to existing speakers is with a HEOS Link, but that is a pretty large and costly device. It would be great if Denon created a playback-only HEOS dongle that with a line out--call it a Linklite. It wouldn't necessarily need to be able to do everything a normal HEOS device does, at a minimum it would just play what is played to your other HEOS device(s). But nearly all wifi speakers have a line-in jack, even Sonos. It would be kind of cool to be able to easily add third party components in this way.
Wishful thinking: if HEOS becomes a more popular home entertainment operating system, perhaps vendors of the other products will embed the software required to be compatible with HEOS.
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Is it possible to create an app that can detect card like a debit card of users using pattern recognition or from photo album just like face detection works in order to detect the face, I’d like to know could we create an app which can detect user's debit card?
I would take a look at card.io
it depends on your team :)
but technically it's possible. even on video stream. I know one team doing similar things - they can detect any dollars banknote on videostream. But they worked in this technology for 5 years. So it's image recognitions with a lot of math - but it's possible.
A debit card or credit card contains a Magnetic strip which contains encrypted info and AFAIK there is no way to read that data with only camera and pattern Recognition.. With camera You can only read the card number, Bank name using OCR or user name if it is printed on the card.. for reading the Magnetic strip data you need a card reader which will be a separate hardware.
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I am planning to develop an gyroscope based project like TipSkip, handle event knock to device from behind or detect a clap ,I searched google but I didn't find anything except core motion guide and event handling guide.
Thanks for any help
Detecting a clap requires audio recognition i.e. frequency analysis. There is no better source than Apple's own AurioTouch example for FFT. There is fairly good material about FFT and auriotouch online as well, like this.
As for the knocks, accelerometer is the way to go and you just need value recognition for the kind of movements your knock generate.
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I have a need to stream video from the iPhone/iPad camera to a server. It looks like this will need to be done with AVCaptureSession but I don't know how to best architect this.
I found this post:
streaming video FROM an iPhone
But it doesn't handle the "live" part, latency needs to be 2 or 3 seconds at most. Devices can be constrained to 4 or 4S capability if needed, and there is no requirement for HD, VGA is probably what we'll end up with. I assume any solution would use ffmpeg, I haven't found any more appropriate library.
How is this best accomplished?
According to Apple, if you send large amounts of data from an iPhone app you're going to have to use HTTP Live Streaming.
HTTP Live Streaming Overview
It's possible, here's an App that does it called Livu
Try working with ffmpeg for iPhone and the segmenter from Carson Macdonald's excellent Ion Cannon site which has a lot of useful information on HTTP Live Streaming. He's a user here too and can offer invaluable advice.