First, thanks to the FFmpeg project, Martin Böhme for his tutorial on using libavformat and libavcodec and David Conrad for the gas-preprocessor project that allows us to compile FFmpeg for the iPhone.

Before you link the FFmpeg libraries to your project, make sure that you understand FFmpeg’s licensing. My project uses the LGPL version of FFmpeg, which means that I have to make FFmpeg’s source code available (included in the project).

Before you create a commercial project that decodes H264 video, make sure that you get a license from MPEG LA.

The source code is posted on github: git://github.com/lajos/iFrameExtractor.git.

To compile and run the project on your iPhone:

1. open Terminal
2. clone the repository: git clone git://github.com/lajos/iFrameExtractor.git
3. go to the ffmpeg folder in the project: cd iFrameExtractor/ffmpeg
4. build the ffmpeg libraries: ./build_universal
5. open the xcode project and run it on your iPhone device

The build_universal shell script creates libraries that work on both armv6 and armv7 processors. If you need libraries for pre-3Gs devices (iPhone 2g, iPhone3G, iPod Touch), use the build_armv6 script. For iPhone 3Gs only libraries, use build_armv7.

iFrameExtractorAppDelegate creates an instance of VideoFrameExtractor (the class that grabs images from the video). When you press the play button, iFrameExtractorAppDelegate sets up a loop and displays all the images from the video until it reaches the end of the movie.

The VideoFrameExtractor class is based on Martin Böhme’s tutorial, upgraded to use swscale. Initialize this class with the full path of the movie:

VideoFrameExtractor *video = [[VideoFrameExtractor alloc]
               initWithVideo:@"/full/path/to/movie.mov"];

By default, the output size will match the movie’s size. You can set outputWidth and outputHeight to change the dimensions:

video.outputWidth = 426;
video.outputHeight = 320;

Use stepFrame to grab the next frame. This method returns false if there are no more frames (reached the end of video):

BOOL result = [video stepFrame];

The processed frame can be accessed as a UIImage on the currentImage property:

UIImage *myImage = video.currentImage;

You can seek to a specific time (in seconds) using the seekTime: method:

[video seekTime:1.0];

The movie’s length can be queried by checking the duration property:

NSLog(@"video duration: %f",video.duration);

This should get you started with extracting frames from iPhone movies If you find any problems, please submit a patch.

Known issues:

• Images are always decoded as landscape.

Most source code templates include __MyCompanyName__ in the comments. To change it, open terminal and type this command replacing __MyCompanyName__ with whatever you want:

defaults write com.apple.Xcode PBXCustomTemplateMacroDefinitions -dict ORGANIZATIONNAME "__MyCompanyName__"

For example:

Restart XCode. New files will be created with the company name you specified.

[rant]

Not sure why you can’t specify this from XCode, but at least there is a way to change it. It would be nice for Apple to fix this, but I’d rather them work on doing away with the moronic single menu bar for all applications, adding a feature to XCode to create text macros, fixing Spaces so my application windows would open on the designated Space, removing the animation from switching between Spaces, … gosh I should start a list for them.

[/rant]

Let’s see what we can do about EXC_BAD_ACCESS.

EXC_BAD_ACCESS happens when a message is sent to an object that has already been released. By the time the error is caught, the call stack is usually gone especially if dealing with multiple threads.

How nice would it be to keep a dummy around after the object is released that could stop execution, tell us what message was sent and show us the call stack… well, there’s a way to do just that.

If you set the NSZombieEnabled environment variable, the Objective C runtime will leave a dummy object behind for every deallocated object. When the zombie object is called, execution stops and you can see the message that was sent to the object and the call stack that tells you where the message came from (it doesn’t tell you where you over released the object, but knowing where the object is called from should get you pretty close to the problem.)

To set this variable, go to the info panel of the executable in xcode, and create a new environment variable in the arguments tab by clicking the plus sign in the lower left corner of the window. Name the variable NSZombieEnabled, type YES for the value and make sure that the checkbox is selected.

set NSZombieEnabled variable

Go ahead and run your program now (in debug mode, because you need the stack information.) When the over released object is accessed, you get an error message similar to this (xcode debug view):

2009-03-30 02:30:36.172 ninjaJumper[3997:20b] *** -[GameLayer retain]: message sent
to deallocated instance 0x59bf670

This shows the class of the object (GameLayer) and the message sent (retain).

Let’s take a look at the stack now:

call stack

The methods printed in bold are in your code, the others are in some other API. Here you can see that the object was accessed from [Director touchesBegan:withEvent], where an array was copied (most likely the over released object was in the array.)

This information should get you pretty close to the problem.

Once the problem is fixed, make sure that the NSZombieEnabled variable is disabled. You don’t need to delete it, but make sure that the checkbox is unchecked:

NSZombie disabled

Now about the wife. Good luck there. Try a box of chocolate or load the dishwasher for a couple days.

There’s no method in the NSString API to decode a UTF-8 NSString directly, so first it has to be converted to a C string (gotta love those C strings.)

NSString *encodedString;
NSString *decodedString = [NSString stringWithUTF8String:[encodedString cStringUsingEncoding:[NSString defaultCStringEncoding]]];

A JSON string looks like this (image from json.org):

NSString is already UTF-8, but characters like \n have to be escaped. Here’s the method I came up with:

-(NSString *)JSONString:(NSString *)aString {
	NSMutableString *s = [NSMutableString stringWithString:aString];
	[s replaceOccurrencesOfString:@"\"" withString:@"\\\"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"/" withString:@"\\/" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"\n" withString:@"\\n" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"\b" withString:@"\\b" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"\f" withString:@"\\f" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"\r" withString:@"\\r" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	[s replaceOccurrencesOfString:@"\t" withString:@"\\t" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
	return [NSString stringWithString:s];
}

Here’s how to rename it to something that makes sense, like pink.

Open System Preferences and click on Sharing in the Internet&Network section:

System Preferences / Sharing

Change the Coumputer Name field:

Computer Name

Click on the Edit button right below the Computer Name field and make sure the name you entered propagated here. You want to see something like pink.local:

Computer Name Edit

Last but not least, you should also change the host name (the system name of your machine). To do this, fire up Terminal (spotlight will find this for you) and type this command replacing pink with your name choice (you will also have to type your admin password):

sudo scutil --set HostName pink.local

Enjoy your now sanely named mac!

Don’t be sad, you can create a bootable USB stick installer from the online download. It’s easy, although you’ll have to get your hands a bit dirty.

You’ll need two utilities:

• PeToUSB to format your USB stick (get the latest version)
• BootSect (I don’t know who made this awesome tool, you can download it from here)

First, format your USB stick (must be 4gb or larger) with PeToUSB (obviously this will wipe out all files on your USB stick). Under format options make sure that you check:

• Enable Disk format
• Enable LBA (FAT16x)

Leace everything else unchecked. Drive label can be whatever. Here’s a screenshot:

PeToUSB format

Extract BootSect.zip somewhere, for example c:\temp.

Now fire up command prompt (windows button+r, type cmd). Go to the folder where BootSect is, for example:

cd c:\temp\bootsect

Assuming your USB stick is drive d:, type (otherwise replace d with your drive letter):

bootsect /nt60 d:

You should see something like this:

bootsect /nt60 d:

Now your USB stick is ready for the Windows7 installation files.

First you have to run the installer to unpack the installation files from the box files. As soon as unloading is done and the installation screen appears, you can close the installer. You’ll have a new folder called expandedSetup:

unboxed windows7 installer

In command prompt cd to the expandedSetup folder, for example:

cd \Users\lajos\Desktop\win7_32\expandedSetup

Copy the installation files to the USB stick using xcopy:

xcopy *.* /s /e /f d:

Now sip on your favorite drink for a while When xcopy finishes, you’ll have a Windows7 USB stick installer!

Reboot your computer from the USB stick and the Windows7 installer should start up.

You can download the modified Export Layers To Files script from here. Unzip the file and overwrite the original one in Photoshop CS4’s Presets/Scripts folder (to try it, run it from Photoshop’s File/Scripts/Browse menu ).

export layers to files, option to suppress layer numbers

The script was originally written by Naoki Hada and Tom Ruark, Copyright 2007.  Adobe Systems, Incorporated.

I added the same option to Leo Davidson’s modified Export Layers To Files (Fast PNG version) script. That script works with Photoshop CS3, you can grab it from here.

The DW1510 uses the Broadcom 4322 chip and supports 802.11n wireless networks and seems to have better reception than the original card. I bought the card for <$20 on eBay. It’s a great upgrade.

The correct driver that work with Windows XP is here: Dell Wireless WLAN 1510 Half MiniCard (4322). The file is called DELL_MULTI-DEVICE_A23_208883.exe.

You should know that if you are installing this card in a non-Dell computer, the Dell installer will not work. You will have to manually update the drivers. Run the installer. You can exit the installation after the files are extracted, although it will exit on it’s own complaining about your hardware if you continue

Right click on My Computer, select Manage. Select the Device Manager, you should see your network card with a yellow question mark show up in he list of devices. Right click on it, select Update Driver… Select Install from a list of specific locations (advanced). In the Include this location in search fiels browse to the extracted driver package, the folder you want to select is called DRIVER (under dell/drivers/R208883). Proceed with the installation and enjoy your new wireless card!

I was surprised because I did not change any build settings. When I looked at the code signing key, I didn’t see any of the installed provisioning profiles:

The provisioning profiles should show up like this:

I checked a bunch of things from my old post about code signing, but I could not fix the issue.

I opened the project.pbxproj file (located in the .xcodeproj folder) and saw that while the CODE_SIGNING_IDENTITY was set, the PROVISIONING_PROFILE key was missing in the Distribution build settings section:

I created a temp project and selected the correct provisioning profile (in the new project I could select it with no problem). I opened the .pbxproj file from the temp project in a text editor (I use Smultron which is awesome) and copied the PROVISIONING_PROFILE setting to MeanPhoto’s .pbxproj:

The provisioning profiles still don’t show up in XCode, but the new build uploaded to iTunes without a problem.