Freelance sound designer PJ Belcher says "everything is just a little bit harder" when designing sound for Apple's iOS, due to the platform's inherent mobility and issues stemming from hardware limitations.
Belcher offers up some tips to overcome iOS sound design challenges -- not the least of which is size limitations for audio assets -- in a new Gamsutra feature
"Possibly the biggest concern of any audio producer for the iPhone will be asset size," writes Belcher. Apple imposes a 20MB over-the-air size limit, meaning any app over that limit will need to be downloaded via wi-fi instead of 3G.
"[Keeping an app below 20MB] is crucial to ensure good sales given the value of viral marketing in selling iPhone apps," said Belcher. "The process is broken if the potential customer has to go and find a wi-fi network or wait until they get home to purchase an app, so under 20MB is a must."
Belcher continues, "This lack of asset space is hard for the audio producer given the size of audio assets, not to mention fighting with other assets for space - -you are looking at a maximum of 50 percent, leaving you just 10MB. Does that immersive, dynamic, innovative soundtrack seem tricky yet?"
"This is assuming that you convince the other people working on the game that your ideas are worth 50 percent of the game!" he added.
"The iPhone doesn't really help matters much either, since it can only decode one compressed file at any time, meaning most of your audio (aside from a few careful choices) has to be in un-compressed PCM formats, which any producer will know are rather large," Belcher explained.
"There are lots of techniques that can be applied to mitigate this, though, such as asset-based generative sound systems, crossfade looping, and carefully selected bouncing."
In the Gamasutra feature
, Belcher also addresses how to better utilize the tiny built-in speakers and headphones of Apple mobile devices, and takes into consideration the widely varying environmental settings that a mobile user might play an iOS game.