Are there some particular library files available on OS/X that are relevant, I am just not sure where to start.
You'd probably want to use the QuickTime for that. There is some sample code that does this. However, it's not the nicest way to access metadata. The newer QTKit Framework somehow still requires you to fall back to the C-based APIs. There is another example from Apple embedding meta data writing into a Objective-C method. This might be the best starting point for you.
Related
I want to know if there is a way in c++ or objective-c to get the BPM of a Mp3 file.
i found until now a source code for stuff that do it on wav files and not on mp3 file,
BPM (or beat) detection is a complicated algorithm that involves analyzing the sound stream in different ways. For this to happen, at least internally the MP3 must be decoded. Typically these are things you'd actually write in a language such as but not limited to C++ or Objective-C.
There are many libraries / pieces of code available that solve both problems, or in the case of beat detection: take a shot at it.
There's certainly no way to do BPM detection in the core C++ or Objective-C languages. You need to write the functionality yourself or take advantage of one of the many libraries that provide it.
If you can't find a suitable library that supports MP3 directly then you're going to have to decode to PCM first.
Is it possible to get and parse JSON using objective C, then manipulate it within the cocoa framework for the iphone/pad? I'm specifically looking to do this for a couple of public APIs out there.
See here: how to do json parsing in iphone
Basically, you should look into the TouchJSON library (with CJSONDeserializer and CJSONSerializer).
Used Json-framework on some previous projects, worked really well.
EDIT: I read your post a bit too fast. I've used it on a Mac app before but not targeting the iphone/ipad. I think it should work but have no background to it. Maybe someone else can confirm?
It's not only possible, it's dirt simple if you use one of the many existing open source projects dedicated to this task. I recommend trying yajl-objc, which offers a streaming parser, but json-framework is a good one too. They're very similar.
I'd stay away from TouchJSON, since it gave me trouble a while back with special characters (line breaks) in strings.
However, I'll join the choir recommending json-framework. Since I switched to that from TouchJSON everything's been running smoothly.
Regarding how to integrate the API in your project, they're equally simple to include and use.
As a side note, I'm just now testing out JSONKit, since it's supposed to be much faster than both TouchJSON and json-framework. However, I can't vouch for its stability yet. The reviews of it are good, though.
If you're developing an application that is only iOS 5.0 or later, you can use NSJSONSerialization.
I was wondering if there were a way to extract information from an objective-c app, static or dynamic library and/or framework?
Information such as an array of class names without instantiating or running the target.
I've checked google and the apple developer documentation and haven't found anything.
Frank
F-script appears to be able to do what you want, but I'm no expert. Check out www.fscript.org.
If you want to extract classes from an application/dynamic library, there is a handy tool called ClassDump.
It can even generate the header files in order to get an overview of the classes, protocols, etc.
If you want to do it at runtime, then take a look at the source code to learn how to load and parse the different mach-o segments.
This is an excellent starting point for reverse-engineering Cocoa apps:
http://culater.net/wiki/moin.cgi/CocoaReverseEngineering
It mentions F-Script, class-dump, and a few others.
For the application I am writing, I need to access some other applications' items, for which Applescript seems the best way to go. I have been using the Appscript framework, which worked well, because it allowed me to thread it and not make my app lock up when an Applescript was taking a while. However, now I am attempting to make my application 64 bit compatible, and it seems like the Appscript framework does not support 64 bit. Is there a "good" way to use Applescript in Cocoa that will not lock up my application, but still give me the full control I need?
--firen
It seems like SBApplication should work, but I haven't used it before.
According to #cocoadevcentral:
SBApplication: use to make cross-application scripting calls with Objective-C instead of AppleScript. Ex: get current iTunes track.
Here is is the excerpt from the documentation:
The SBApplication class provides a mechanism enabling an Objective-C program to send Apple events to a scriptable application and receive Apple events in response. It thereby makes it possible for that program to control the application and exchange data with it. Scripting Bridge works by bridging data types between Apple event descriptors and Cocoa objects.
Although SBApplication includes methods that manually send and process Apple events, you should never have to call these methods directly. Instead, subclasses of SBApplication implement application-specific methods that handle the sending of Apple events automatically.
For example, if you wanted to get the current iTunes track, you can simply use the currentTrack method of the dynamically defined subclass for the iTunes application—which handles the details of sending the Apple event for you—rather than figuring out the more complicated, low-level alternative:
[iTunes propertyWithCode:'pTrk'];
If you do need to send Apple events manually, consider using the NSAppleEventDescriptor class.
Hope that helps!
As Blaenk mentioned Scripting Bridge may well be the way to go, although it can prove somewhat inefficient if you have to iterating through large arrays etc.
The simplest way to run an Applescript in Cocoa is using NSAppleScript.
Apple has some pretty good examples, which I found useful when I needed to do something similar. There are three articles you might want to take a look at. They all contain some sample code, which I always find very useful.
A Few Examples of using Scripting Bridge
Performance & Optimisation with Scripting Bridge
NSAppleScript Technote/Example
I created a gist with the full URLs as I can't post more than one link, what with being a newbie and all.
http://gist.github.com/130146
it seems like the Appscript framework does not support 64 bit.
Should work. Make sure you set the correct architectures and SDK (64-bit requires 10.5) in the Xcode project. File a bug report if you have a specific problem.
Is it possible to access the iSight camera on a macbook programmatically? By this I mean I would like to be able to just grab still frames from the iSight camera on command and then do something with them. If so, is it only accessible using objective c, or could other languages be used as well?
You should check out the QTKit Capture documentation.
On Leopard, you can get at all of it over the RubyCocoa bridge:
require 'osx/cocoa'
OSX.require_framework("/System/Library/Frameworks/QTKit.framework")
OSX::QTCaptureDevice.inputDevices.each do |device|
puts device.localizedDisplayName
end
I don't have a Mac here, but there is some Documentation up here:
http://developer.apple.com/documentation/Hardware/Conceptual/iSightProgGuide/01introduction/chapter_1_section_1.html
It looks like you have to go through the QuickTime API. There is supposed to be a Sample Project called "MungGrab" which could be worth a look according to this thread.
If you poke around Apple's mailing lists you can find some code to do it in Java as well. Here's a simple example suitable for capturing individual frames, and here's a more complicated one that's fast enough to display live video.
There's a command line utility called isightcapture that does more or less what you want to do. You could probably get the code from the developer (his e-mail address is in the readme you get when you download the utility).
One thing that hasn't been mentioned so far is the IKPictureTaker, which is part of Image Kit. This will come up with the standard OS provided panel to take pictures though, with all the possible filter functionality etc. included. I'm not sure if that's what you want.
I suppose you can use it from other languages as well, considering there are things like cocoa bridges but I have no experience with them.
Googling also came up with another question on stackoverflow that seems to address this issue.
Aside from ObjC, you can use the PyObjC or RubyCocoa bindings to access it also. If you're not picky about which language, I'd say use Ruby, as PyObjC is horribly badly documented (even the official Apple page on it refers to the old version, not the one that came with OS X Leopard)
Quartz Composer is probably the easiest way to access it, and .quartz files can be embed in applications pretty easily (and the data piped out to ObjC or such)
Also, I suppose there should be an example or two of this in the /Developer/Examples/
From a related question which specifically asked the solution to be pythonic, you should give a try to motmot's camiface library from Andrew Straw. It also works with firewire cameras, but it works also with the isight, which is what you are looking for.
From the tutorial:
import motmot.cam_iface.cam_iface_ctypes as cam_iface
import numpy as np
mode_num = 0
device_num = 0
num_buffers = 32
cam = cam_iface.Camera(device_num,num_buffers,mode_num)
cam.start_camera()
frame = np.asarray(cam.grab_next_frame_blocking())
print 'grabbed frame with shape %s'%(frame.shape,)