Some days ago I saw a interesting device for iphone, square, here: https://squareup.com/
you can plug it into iphone's earphone socket, and it can transfer data to iphone. A running App on iphone can receive it.
does any one know how it implemented? I guess it can encode data to audio stream and "sing" it, and App on phone can record the sound and decode it. but how to? is there a protocol or SDK?
The implemention is likely to be no different to that of a simple acoustic modem. The relevant APIs include Audio Units (low-level) or Audio Queue Services (higher level).
Matt Gallagher has written an excellent (as always!) post on creating an iOS tone generator, which is one way of enabling what you are after.
Related
If it helps, I am using Xcode 4.3.1 and objective-c to program simple apps on an iPhone 4s running iOS 5.1.
I would like to find the documentation for a class with methods to capture the digital music signal that iTunes sends to an output device (speaker, headphones). I assume it must be accessible since it exists in the phone prior to reaching the speakers. I am not attempting a pirating move, but rather would like to route this music signal to the phone's outgoing wireless signal so that it can be heard clearly by someone on the other end of a call (ex. a method to play a favorite song, with decent sound quality, for a friend out of town). Can anyone point me in a general direction (if that direction exists) so that I can begin learning more?
Thanks,
Seth
One, I'm pretty sure there's no way to get the raw audio samples from a song in the library. You can get a list of the tracks and tell the system to play one, but that all happens outside your app. Two, apps can't access the cell phone—there's no way to send audio from your app to a phone call. Three, even if the first two did work, calls are heavily compressed and tuned to voice data. Call a friend and have them play a song through the phone, see how it sounds. Not very good, I'll bet.
Is it possible to transfer data from/to iphone through headset using some modulation(fsk for example)? From theoretical point of view it looks completely possible.
Yes, you could consider in-code FSK demodulation.
Take a look at O'Reilly's iPhone Hacks - there's a nice chapter on serial modem.
True - it uses Headphone Jack but you'll get the feeling on how to handle audio 'data'.
You can also download the source from iPhone Hacks source code
EDIT: there's also an awesome link collection in not really Jake's answer here:
Using an iPhone audio dongle to transmit data
I'm not very well versed in the iPhone and Android API, so please bear with me if this is a stupid question.
As I understand it, Square's card reader works by converting the magnetic information on the card stripe into an audio tone that its software can then process. [1]
In a similar way, is there a way to somehow read what exactly is being displayed on the device screen simply through a small device inserted into the audio jack on that device?
[1] http://www.quora.com/How-does-Squares-hardware-work
It's not quite clear what you wish to achieve. You can indeed make an app that would output a representation (perhaps audio frequency-shift keying?) of the screen's contents to the iPhone's audio jack.
The iPhone (and other iOS-based devices) use TRRS connectors for bi-directional audio (and hence arbitrary modulated data) communication and there are well-supported publicly-documented APIs for using these interfaces.
That said, if you're writing your own app: why would you want to output the contents of the screen? If you are developing the app in question, why not transmit the salient data in a more effective manner? Which leads me to my next assumption:
You want to read what's being displayed on the device's screen at any time, not just when an app of your creation is open. In this case, the answer is that it is not possible, with the possible exception of a jailbroken solution. That said, I can't imagine a jailbroken solution being useful much longer on account of iOS 5 introduced "display mirroring" by means of AirPlay.
On Android, I have no idea. :-)
No. The screen is not connected to the audio jack.
I think you can make an app to take a screenshot and then encode that photo as music to play it.
It won't sound good though :)
For this kind of task, there is built in camera
I'd like to get real-time video from the iPhone to another device (either desktop browser or another iPhone, e.g. point-to-point).
NOTE: It's not one-to-many, just one-to-one at the moment. Audio can be part of stream or via telephone call on iphone.
There are four ways I can think of...
Capture frames on iPhone, send
frames to mediaserver, have
mediaserver publish realtime video
using host webserver.
Capture frames on iPhone, convert to
images, send to httpserver, have
javascript/AJAX in browser reload
images from server as fast as
possible.
Run httpServer on iPhone, Capture 1 second duration movies on
iPhone, create M3U8 files on iPhone, have the other
user connect directly to httpServer on iPhone for
liveStreaming.
Capture 1 second duration movies on
iPhone, create M3U8 files on iPhone,
send to httpServer, have the other
user connected to the httpServer
for liveStreaming. This is a good answer, has anyone gotten it to work?
Is there a better, more efficient option?
What's the fastest way to get data off the iPhone? Is it ASIHTTPRequest?
Thanks, everyone.
Sending raw frames or individual images will never work well enough for you (because of the amount of data and number of frames). Nor can you reasonably serve anything from the phone (WWAN networks have all sorts of firewalls). You'll need to encode the video, and stream it to a server, most likely over a standard streaming format (RTSP, RTMP). There is an H.264 encoder chip on the iPhone >= 3GS. The problem is that it is not stream oriented. That is, it outputs the metadata required to parse the video last. This leaves you with a few options.
Get the raw data and use FFmpeg to encode on the phone (will use a ton of CPU and battery).
Write your own parser for the H.264/AAC output (very hard)
Record and process in chunks (will add latency equal to the length of the chunks, and drop around 1/4 second of video between each chunk as you start and stop the sessions).
"Record and process in chunks (will add latency equal to the length of the chunks, and drop around 1/4 second of video between each chunk as you start and stop the sessions)."
I have just wrote such a code, but it is quite possible to eliminate such a gap by overlapping two AVAssetWriters. Since it uses the hardware encoder, I strongly recommend this approach.
We have similar needs; to be more specific, we want to implement streaming video & audio between an iOS device and a web UI. The goal is to enable high-quality video discussions between participants using these platforms. We did some research on how to implement this:
We decided to use OpenTok and managed to pretty quickly implement a proof-of-concept style video chat between an iPad and a website using the OpenTok getting started guide. There's also a PhoneGap plugin for OpenTok, which is handy for us as we are not doing native iOS.
Liblinphone also seemed to be a potential solution, but we didn't investigate further.
iDoubs also came up, but again, we felt OpenTok was the most promising one for our needs and thus didn't look at iDoubs in more detail.
I'd like to stream video from the camera on an iOS device to a receiver via wifi, in effect turning the device into a wireless webcam. Is there a way to build a small app that captures video input on an iOS app and sends it via an RTSP stream or similar?
As this is an ad hoc experiment, I'm not concerned about App Store guidelines and can jailbreak if necessary.
If I interpret your question correctly you more or less need to solve four problems:
Get the camera feed.
Convert/encode this to the right format.
Stream the data.
Prevent the phone from locking itself and going into deep sleep.
The first one is fairly simple and Apple has as always provided good documentation and examples -> API link. Make sure you check out their example in the end as you will get a CMSampleBufferRef data object back.
For the second and third part, you should check out the CFNetwork framework and specially CFFTPStream for streaming using FTP.
If your are only building this for yourself then you can always turn off the Auto-Lock feature in the settings. If you on the other hand would like to distribute this to other users you could use a trick to play a mute sound every 10 seconds. This is more or less how all the alarm clocks work in the App Store. Here's a tutorial. =)
I hope I helped a little bit at least.
Good luck and best regards!
I'm 70% of the way to doing the same thing. Here's how I did it:
Capture content from video input
Chop video into files for use in HTML Live Streaming.
Spin up a web server on the iPhone and make the video files available.
Connect to the IP address of the phone and viola! you've got live streaming video.
Last time I touched the code I was trying to debug my Live Streaming not working. I'll try and get my source code posted on github this weekend, if you'd like to take a look.