More cool tips on working with audio development for the iPhone, this time from Nathan Madsen at iDevGames.
Because creating audio content specially for the iPhone isn’t too drastically different than creating audio for any other game, this article is a relatively brief collection of tips about how to best adjust audio for the iPhone.
Where’s the bass?!
The iPhone has one external speaker at the bottom end of the device, and a headphone jack at the top left location. The speaker is very small but has decent quality, however you will get very little low end bass from the speaker. The headphones will give you a much better stereo mix. As long as you are aware that your audio can be heard in either of these ways, and plan for it, you can create audio that sounds appropriate and solid in both situations.
File size and type
File types are important on the iPhone, especially MP3s. The iPhone cannot stream multiple MP3 files at once. The most common way to approach the sounds in a game is to have music be a streaming MP3 file (at stereo 128k if the file size is small enough, mono if it needs to be smaller) and use WAV or CAF for the one hit SFX (Sound Effects). SFX are usually down sampled to 22k but that can depend on the game’s graphics and other processing needs. The more simple the game, the more CPU power you have to work with audio and vice versa. When contracting out for a game, always ask the client what the maximum file size is for the streaming music. One of my clients required about 1.5 MB which is equivalent to about a minute and a half or so of music. Another client wanted two and a half minutes of streaming music, so it can vary from project to project.
If possible, attempt to make alternative versions of the same song, and give them to the client. It can be as simple as muting several of the tracks, changing the instrumentation, or performing a different solo. For a client that is open to a larger audio footprint this can really help keep the music within a certain size (per each individual file) but give more variety and make the music less repetitive.
Via The Sonic Spread