Return to the beginning of an array with a ternary operator

Often times when iterating and looping over the contents of an array, I want to set the current index to zero if it's reached the last element. Generally this happens in the form of an if/else statement, but I enjoy using a more terse form with the help of a ternary operator. See the code below, and enjoy!

var myArray = ['one', 'two', 'three', 'four'];
var curIndex = 0;

setInterval(function(){
    console.log(myArray[curIndex]);
    curIndex = (curIndex < myArray.length - 1) ? curIndex + 1 : 0;
}, 500);

iOS: Force audio output to speakers while headphones are plugged in

After much searching through Apple documentation and scarce examples of what I wanted to do, I came up with the following code. A client wanted to play audio through the iPhone/iPad speakers while a microphone was plugged in. While this solution can't do both at the same time, it will let you switch back and forth between playing sounds through the speakers, then record through a microphone or a headset, without unplugging anything. It will also default to use the internal microphone and speakers if nothing is plugged in. Note that by calling the setup method, audio output will initially be forced through the speakers, rather than the headphones, if plugged in. Hopefully this code helps someone facing similar issues.

AudioRouter.h

@interface AudioRouter : NSObject

+ (void) initAudioSessionRouting;
+ (void) switchToDefaultHardware;
+ (void) forceOutputToBuiltInSpeakers;

@end

AudioRouter.m

#import "AudioRouter.h"
#import <AudioToolbox/AudioToolbox.h>
#import <AVFoundation/AVFoundation.h>

@implementation AudioRouter

#define IS_DEBUGGING NO
#define IS_DEBUGGING_EXTRA_INFO NO

+ (void) initAudioSessionRouting {
    
    // Called once to route all audio through speakers, even if something's plugged into the headphone jack
    static BOOL audioSessionSetup = NO;
    if (audioSessionSetup == NO) {
        
        // set category to accept properties assigned below
        NSError *sessionError = nil;
        [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error: &sessionError];
        
        // Doubly force audio to come out of speaker
        UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
        AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);
        
        // fix issue with audio interrupting video recording - allow audio to mix on top of other media
        UInt32 doSetProperty = 1;
        AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(doSetProperty), &doSetProperty);
        
        // set active
        [[AVAudioSession sharedInstance] setDelegate:self];
        [[AVAudioSession sharedInstance] setActive: YES error: nil];
        
        // add listener for audio input changes
        AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, onAudioRouteChange, nil );
        AudioSessionAddPropertyListener (kAudioSessionProperty_AudioInputAvailable, onAudioRouteChange, nil );
        
    }
    
    // Force audio to come out of speaker
    [[AVAudioSession sharedInstance] overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:nil];
    
    
    // set flag
    audioSessionSetup = YES;
}

+ (void) switchToDefaultHardware {
    // Remove forcing to built-in speaker
    UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_None;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);
}

+ (void) forceOutputToBuiltInSpeakers {
    // Re-force audio to come out of speaker
    UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);
    

}

void onAudioRouteChange (void* clientData, AudioSessionPropertyID inID, UInt32 dataSize, const void* inData) {
    
    if( IS_DEBUGGING == YES ) {
        NSLog(@"==== Audio Harware Status ====");
        NSLog(@"Current Input:  %@", [AudioRouter getAudioSessionInput]);
        NSLog(@"Current Output: %@", [AudioRouter getAudioSessionOutput]);
        NSLog(@"Current hardware route: %@", [AudioRouter getAudioSessionRoute]);
        NSLog(@"==============================");
    }
    
    if( IS_DEBUGGING_EXTRA_INFO == YES ) {
        NSLog(@"==== Audio Harware Status (EXTENDED) ====");
        CFDictionaryRef dict = (CFDictionaryRef)inData;
        CFNumberRef reason = CFDictionaryGetValue(dict, kAudioSession_RouteChangeKey_Reason);
        CFDictionaryRef oldRoute = CFDictionaryGetValue(dict, kAudioSession_AudioRouteChangeKey_PreviousRouteDescription);
        CFDictionaryRef newRoute = CFDictionaryGetValue(dict, kAudioSession_AudioRouteChangeKey_CurrentRouteDescription);
        NSLog(@"Audio old route: %@", oldRoute);
        NSLog(@"Audio new route: %@", newRoute);
        NSLog(@"=========================================");
    }
    
    
    
}

+ (NSString*) getAudioSessionInput {
    UInt32 routeSize;
    AudioSessionGetPropertySize(kAudioSessionProperty_AudioRouteDescription, &routeSize);
    CFDictionaryRef desc; // this is the dictionary to contain descriptions
    
    // make the call to get the audio description and populate the desc dictionary
    AudioSessionGetProperty (kAudioSessionProperty_AudioRouteDescription, &routeSize, &desc);
    
    // the dictionary contains 2 keys, for input and output. Get output array
    CFArrayRef outputs = CFDictionaryGetValue(desc, kAudioSession_AudioRouteKey_Inputs);
    
    // the output array contains 1 element - a dictionary
    CFDictionaryRef diction = CFArrayGetValueAtIndex(outputs, 0);
    
    // get the output description from the dictionary
    CFStringRef input = CFDictionaryGetValue(diction, kAudioSession_AudioRouteKey_Type);
    return [NSString stringWithFormat:@"%@", input];
}

+ (NSString*) getAudioSessionOutput {
    UInt32 routeSize;
    AudioSessionGetPropertySize(kAudioSessionProperty_AudioRouteDescription, &routeSize);
    CFDictionaryRef desc; // this is the dictionary to contain descriptions
    
    // make the call to get the audio description and populate the desc dictionary
    AudioSessionGetProperty (kAudioSessionProperty_AudioRouteDescription, &routeSize, &desc);
    
    // the dictionary contains 2 keys, for input and output. Get output array
    CFArrayRef outputs = CFDictionaryGetValue(desc, kAudioSession_AudioRouteKey_Outputs);
    
    // the output array contains 1 element - a dictionary
    CFDictionaryRef diction = CFArrayGetValueAtIndex(outputs, 0);
    
    // get the output description from the dictionary
    CFStringRef output = CFDictionaryGetValue(diction, kAudioSession_AudioRouteKey_Type);
    return [NSString stringWithFormat:@"%@", output];
}

+ (NSString*) getAudioSessionRoute {
    /*
     returns the current session route:
     * ReceiverAndMicrophone
     * HeadsetInOut
     * Headset
     * HeadphonesAndMicrophone
     * Headphone
     * SpeakerAndMicrophone
     * Speaker
     * HeadsetBT
     * LineInOut
     * Lineout
     * Default
    */
    
    UInt32 rSize = sizeof (CFStringRef);
    CFStringRef route;
    AudioSessionGetProperty (kAudioSessionProperty_AudioRoute, &rSize, &route);
    
    if (route == NULL) {
        NSLog(@"Silent switch is currently on");
        return @"None";
    }
    return [NSString stringWithFormat:@"%@", route];
}

@end

Inspiration: Yoichiro Kawaguchi

If you get into any of the many facets of creative coding or graphical programming, you inevitably run into the history of the demoscene. I don't know too much about the specific history, but I enjoy watching old and new demos and learning more about the building blocks of modern generative graphics techniques. My good friend and veteran graphical programmer Kris just introduced me to one of the original masters and pioneers, Yoichiro Kawaguchi. It seems that he's gone into some really interesting territory with his work, including creation of toys and physical sculptures based on his algorithmic work. I've included some videos and visuals, as well as some links to show off some of what I found:

283 Useful Ideas from Japan - 1990 - The Techno Deep



Origin (1985)



Embryo (1988)



Mutation (1992)



Gigalopolis (1995)



Cyloton (2002)



Yoichiro Kawaguchi Exhibition at Yushima Seido (2009)



Virtual creature simulations (2011)



Gross Tendril (2012)





Links:

• Standing ovation for robot musicians (BBC) (video)

JavaScript: Throttle requestAnimationFrame to maintain 30fps

One problem with using requestAnimationFrame is that rendering will take place as quickly as the computer can process the per-frame calculations and screen redraw. If you only want to run at 30fps, your computer might be running a lot faster than you want. To work around this problem, simply check the elapsed time before running the next frame update. Check out the example:

var frameLength = 33; // this is ~1/30th of a second, in milliseconds (1000/30)
var lastFrame = 0;

var render = function() {
  if(Date.now() - lastFrame > frameLength) {
    lastFrame = Date.now()

    // run your 30fps code here...
  }
  requestAnimationFrame(render);
};
requestAnimationFrame(render);

You'll notice that I'm using Date.now(), which requires a polyfill for old versions of IE. requestAnimationFrame also requires a polyfill for some browsers. Another solution is to use time-based calculations, but that's not always easy to implement.

Bookmarklet: Scrub through a Vine video

I was watching a friend's Vine video on the web, and I got the idea that it would be cool to control the playback of the video. I wrote this little bookmarklet to scrub through the video as you move your mouse over it. Here's the original JavaScript:

// grab video element and pause it
var vid = document.getElementById('post_html5_api'); 
vid.pause(); 
// get x offset of video
var vidX = 0; 
var el = vid;
while (el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
  vidX += el.offsetLeft;
  el = el.offsetParent;
}
// scrub the video based on mouse x
var vidTime = vid.seekable.end(0); 
vid.addEventListener('mousemove', function(e) {
  var x = e.clientX - vidX;
  var percent = x / vid.offsetWidth;
  vid.currentTime = percent * vidTime;
}, false);

And the bookmarklet (Vine Scrubber):

javascript:(function()%7Bvar%20vid=document.getElementById('post_html5_api');vid.pause();var%20vidX=0;var%20el=vid;while(el&&!isNaN(el.offsetLeft)&&!isNaN(el.offsetTop))%7BvidX+=el.offsetLeft;el=el.offsetParent;%7Dvar%20vidTime=vid.seekable.end(0);vid.addEventListener('mousemove',function(e)%7Bvar%20x=e.clientX-vidX;var%20percent=x/vid.offsetWidth;vid.currentTime=percent*vidTime;%7D,false)%7D)();