1. You can’t play two compressed (aac, mp3, alac) files at the same time because there is only one hardware uncompressor available. Here’s a little more info from Apple’s documentation:

The following list summarizes how iPhone OS supports audio formats for single or multiple playback:

• Linear PCM and IMA4 (IMA/ADPCM) You can play multiple linear PCM or IMA4 format sounds simultaneously in iPhone OS without incurring CPU resource problems. The same is true for the AMR and iLBC speech-quality formats, and for the µ-law and a-law compressed formats.
• AAC, MP3, and ALAC (Apple Lossless) Playback for AAC, MP3, and ALAC sounds uses efficient hardware-based decoding on iPhone OS–based devices, but these codecs all share a single hardware path. The device can play only a single instance of one of these formats at a time.

The single hardware path for AAC, MP3, and ALAC audio entails implications for “play along” style applications, such as a virtual piano. If the user is playing a sound in one of these three formats in the iPod application, then your application—to play along over that audio—must use one of the software-decoded formats: linear PCM, IMA4, AMR, iLBC, µ-law, or a-law.

2. Use the compressed format for the largest file (for example, background music.) In my case, I’m using a very compressed mp3. (22050 sample rate, mono, low quality VBR).

3. Use Audacity (I’m using the beta with no problems) to create your compressed mp3s. It provides a nice GUI for you to trim your sound file.  The sampling rate is in the lower left corner of the window, and you can change the variable-bit-rate range by selecting File->Export…, selecting mp3 as your format, and clicking the ‘Options’ button.

4. For your other sounds, like sound effects, that you’d like to play concurrently with your background music, run the following command in Terminal to convert your sounds to a software-compressed format (I’m using IMA4, seems to be the best size/quality compromise). I first tried to use sox, but afconvert will more reliably give you a file that the apple development environment is happy with:

% afconvert -d 'ima4' -f 'caff' inputfile.mp3 outputfile.caf

You can also check to make sure they are readable by the iPhone SDK with afinfo and listen to them with afplay. IMA4 is a compressed format but the quality seems to be pretty decent.

5. AVAudioPlayer is a very easy way to get compatible sound files into your application. It only works on OS 2.2 or greater. To use it,


#import <AVFoundation/AVFoundation.h>

bgMusicPlayer = [AVAudioPlayer alloc ];
[bgMusicPlayer initWithContentsOfURL: [NSURL fileURLWithPath:
[ [ NSBundle mainBundle ] pathForResource: @”street_level-small”
ofType:@”mp3″
inDirectory:@”/” ] ]
error:nil
];

[bgMusicPlayer prepareToPlay];

// when you want to play the file

[bgMusicPlayer play];

You will also need to include the AVFoundation framework. Ctrl-click (or right click) on Frameworks in your Xcode window, then select Add->Existing Frameworks…  The AVFoundation framework is in /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.2.sdk/System/Library/Frameworks/


Good luck!

Hat tips to AkumaStreak on the #cocos2d-iphone irc channel and Sirr & Vadan Less from Integrated Alchemy for pointing me in the right directions.

Anyway, I have just started out, so not much to report yet other than encouraging anyone else interested in iPhone game development to download it. (link)

It has a nice object model around Scenes, Layers, and Sprites, and has a lot of fun game functionality built in. I’ll post more as my project continues.

flickr photo by Arlo Bates

My wife and I had some friends over for dinner tonight, as a non-seder Passover celebration, just to hang out and enjoy some good food and company. Inspired by reading Dr. Sue’s Open That Bottle Night blog post, I decided to open a dusty birthday present from years ago to go along with the lamb chops I was making. It ended up being delicious, a dry red wine, as it said on the bottle, with a beautiful dark burgundy color. I made lamb chops with a pan sauce (referring to the Joy of Cooking a bit to get the general idea). My wife made soup, sides and dessert and our friends brought another bottle of wine and a fancy salad. I’m so glad we were inspired to open the wine, it was awesome to share a good meal and good wine.

Here’s the full menu:

1999 Barone Cornacchia Montepulciano d’Abruzzo

Vegetarian matzoh ball soup

Mixed greens with dried cranberries, candied walnuts and goat cheese

Green beans with almonds

Curried apples with sweet potatoes

Lamb chops with red wine reduction

Chocolate-covered matzoh and candied fruit slices

Quick tip - my parents have a Meyer Lemon tree in their backyard. I got a big bag of lemons from the tree to make a delicious sorbet, but it turned out I only needed eight lemons, not a giant bag-full. So I juiced all of the lemons, then put the juice into an ice cube tray. Perfect for cocktails or just with some club soda.

My first try, which failed, was because my yeast was dead. I followed the directions (I thought), and it smelled yeasty, but once I mixed it all together and kneaded it in the mixer, with the dough hook, it never got past the sticky stage. I let it sit overnight but it never got to the ‘fingerprint doesn’t bounce back’ stage of the first rising. I googled a lot for ‘failed dough’ and tried some of the dough to make breadsticks but they didn’t quite taste right.

This time, I made sure the water was nice and hot (110 degrees F) and stuck the measuring cup with the water and yeast into our turned-off oven (since the rest of the apartment is so cold). You can see from the pictures that it is much more bubbly and frothy when the yeast is actually working. After that, I just followed the recipe and used both the thump and temperature test at the end. Result: tasty home-made bread!

Bad yeast

Good yeast

Today’s project was some delicious belgian waffles. mmm! I made them a little healthier than the recipe called for, but didn’t do any super low-fat, apple-sauce substitutions. I used the Joy of Cooking recipe, which is:

Preheat the waffle iron. Mix the dry ingredients in a bowl:

• 1 3/4 cups flour (I used whole wheat)
• 1 tablespoon baking powder
• 1 tablespoon sugar
• 1/2 teaspoon salt

Blend well in another bowl:

• 3 eggs (I used 2 eggs and 2 whites)
• 1/2 to 2 sticks butter (I used a half stick, melted in the microwave)
• 1 1/2 cup milk (I used nonfat)

Make a well in the center of the dry ingredients and pour in the wet ingredients. Combine with a few swift strokes of the whisk.

They came out amazingly well, thanks to a good waffle iron and some home-made maple syrup from a friend in upstate New York. Delish!

Step 1: connect the laser pointer to the arduino. I stuffed one wire into the spring, and wired that to the GND pin. Then I taped the 5V wire to an alligator clip and clipped that to the end of the barrel. Plugged into usb and voila - the arduino is powering the laser.

Step 2. A few google searches later, and I found a handy blog entry with a morse code generator for Arduino. Upload the sketch, change the pin to my pin for the laser, and voila!