I want to make an App for concert. Basically this will serve a lights sync on the music played in the concert. The flashing of lights should be in sync in the beat or music at the concert.
Something like this:
https://itunes.apple.com/us/app/dan-deacon/id536378735?mt=8
Question is
Is the app listening to the music thru the microphone?
If it is listening, how does it know when to flash the lights based on the beat of the music or the music itself?
In the example app I posted it's not using any wifi or mobile data so does it mean that it's standalone and does #1 and #2?
I have this question coz I'm new to app development. I want to do those feature but my idea is that there is a server which we control that will just send the lights flashing pattern on those apps, my concern is that if there's were 100,000 people in the event, provided the all have a wifi connection, will the sending of flashing lights pattern be a problem espcially you are sending hundred thousands of commands at the same time? I would prefer it to be in offline mode but how till it exactly work?
That is an amazing app. You need to synchronize your apps to the musik and maybe the apps among them selfs.
I picked some links for you:
http://content.iospress.com/articles/journal-of-embedded-computing/jec00021
http://www.cse.wustl.edu/~cdgill/PDF/RTSS08.pdf
http://blog.trifork.com/2013/02/18/build-build-massively-scalable-soft-real-time-systems-with-erlang/
In praxis i can imagine that the user starts playing the song and the app synchonize by the recorded sounds...
Related
I am relatively new to iOS app development and I'm just trying to figure out some things that, to me, are more abstract. How do apps know when other apps start? The closest example I can think of to what I'm trying to ask is when music is playing in the background and you open another app that has sound and the music stops. Is that the new app taking authority or is there inter app communication? If there is communication how does that communication work? Like is it a message that could be accessed or what?
Sorry if that didn't make much sense, I tried to elaborate the best I could. I couldn't find anything on this on apple's developer website. Thanks in advance!
There is no inter-app communication. Each app is living in its own world, and as far as your app is concerned, it's the only app on the phone. The way communication happens is that an app talks to the system, and the system talks to your app. The way the system sends messages to your app is usually in the delegate of the framework you're working with. In your example, opening your app to play audio will send a message to the system, and the system will tell the other app to stop audio playback. That other app has no idea it was your app that initiated the stop. Another example is the AppDelegate. The app delegate will send your app messages such as application:didFinishLaunchingWithOptions:, which in this method is where you do custom initialization of the app or applicationWillResignActive: which is normally sent when the user presses the home button or receives a phone call, so here you might want to save your game, etc.
In fact the iOS system is quite complicated, much to complicated to be explained in detail here so I highly suggest reading the Apple Developer Documentation, some of it can be a little dry, but they do their best to be coherent with even absolute beginners.
Can information that gets transferred through the headphone jack be stolen by a backgrounded app?
Square makes a card reader that plugs into the headphone jack of the iPhone and transfers your credit card info to your phone.
There are many devices that transfer data through the headphone jack.
Since you can run background processes now on iOS, can that information that is being transferred be intercepted or monitored by an app running in the background?
Could a random app potentially be listening and looking for credit card numbers and steal the information?
If yes, then is there a way to cancel all other app's listening connection to the headphone jack while I transfer my own data from a device?
I have looked at the AurioTouch example of how to transfer data but all I need to know right now is if my data is in jeopardy of being stolen and how I can prevent that.
See the last paragraph of "Playing and Recording Background Audio" here.
To sum it up, you can stop your app from playing or recording audio if another app wants to play/record audio. Look into AVAudioSession.
You should be equally worried about the possibility of audio being intercepted on the outside of the device as audio. Such man-in-the-middle attacks have been reported against chip-and-pin terminals, and usually involve corrupt employees of the retailer using the device or social engineering.
The only solution is to encrypt the data. This makes the question of interception on the device irrelevant.
I have a rather odd question. I am writing a turn based iOS game and was wondering if there is a way to store data in your application that can be accessed even when the app is closed. I have a handful of NSStrings that I would like GameCenter to be able to swoop by and scoop up even if the app is closed on the user's device. Is this possible? I know it won't work while the device is off, but it would be nice if they don't have to have my app open for it to collect their turn.
Any background processes have about 30 seconds to complete once your app is put in the background except for specific processes like playing music etc, so basically no not really. You can see the docs here:
Multitasking docs
I've set up an HTTP live stream of a screen capture of my computer and the necessary client-end code in iOS to watch the live stream, which I'm using to stream the "spectate" mode of the game League of Legends, which is running on my machine.
I'm wondering what would be involved in making this an app that other people could use to watch any game of League of Legends. I have almost zero experience with servers as my background is in iOS, but would it be possible to start up a VM with League of Legends and VLC and the screen-capture software for each client requesting to spectate a different game?
I'm guessing I could set this up if I had a machine for each client requesting a stream, but I don't really know whether or how I can run many VMs on a server and what that would cost me.
check out something like justin.tv (http://www.youtube.com/watch?v=QP4HfCOfeUQ)
There are a number of other application virtualization technoliges as well. check out http://en.wikipedia.org/wiki/Microsoft_App-V and the list at the bottom of similar products.
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.