Sound Programming in the Apple iPhone OS Environment PDF Manual Guide
Over the last years an increasing number of music applications and games have been released. The iPhone platform has good variety in this field. However, most often the audio quality is not a prioritised feature, having bad impact on the perceived product quality. This bachelor thesis describes the different sound programming interfaces available on the iPhone platform and how to use them to generate a high fidelity realtime audio stream. This is achieved using techniques for variations in sounds and multi channel mixing while keeping a low latency and high sound quality. This thesis shows that real time audio synthesizing is possible on the iPhone platform through the library framework provided by Apple.
After reading this work, one will have a broader knowledge about the available sound API on the Apple iPhone and sound usage in general.
As technology develop further and further devices become both smaller and more powerful[18]. With small portable devices such as Apple’s iPhone the only interface is the touch screen, therefore we have in this project investigated the use of alternative input using the microphone. This has been done by developing a real time instrument simulator. To make the instrument sound more natural, some techniques such as variating sounds has been investigated. This thesis is one of two in the project, my (Benjamin Eriksson) part describes how to handle high quality audio in and output in the Apple iPhone environment with it’s limited resources and how it is implemented in the iPhone project. Tomas Härdin’s part is about classifying sounds on a real time audio stream. The project has been developed at a software developing company called CodeMill AB.
1.1 Background
In late december 2008 CodeMill AB wanted to participate in a project with another local company specialized in audio software. The partner wanted to expand to the iPhone market and therefore choose to work with CodeMill. An idea of a real-time drum application which would get the input from the device’ microphone was invented. The idea was inspired by two papers on scratch input[5] and acustic emanations of computer keyboards[25]. One of the criteria for the application was to have high fidelity audio with a latency lower than 25 ms1 . This was necessary as the partnership company’s reputation lies in giving the end user the most high quality sound availible.
To be able to develop applications to Apple’s iPhone environment one must use Apple’s own development suite. This since the iPhone environment is a closed platform. The development environment is free for everyone to download and install. Applications can be installed and debugged on the iPhone Simulator in the development suite. But in order to debug on the target device, such as the iPhone and iPod touch, one must apply for the iPhone Developer Program[10]. The iPhone Simulator is however not an emulator, and does only simulate high level APIs on the host native architecture and can therefore not be used for low level
API’s and performance tests.
The Apple App Store is where the end user buys iPhone applications. The App Store can either be accessed via the iTunes Store in iTunes on a PC or Mac, or directly via an application on the device. The price for an application is set by the developer. Apple takes a 30% cut of the revenue for providing the distribution channel.
3.1 iPhone Development Setup
The iPhone development setup includes the Xcode development environment, which includes an integrated text editor as well as a graphical debugger[10]. Interface Builder is a design tool for creating graphical user interface for the CocoaToch framework. Instrumments is used for measuring processor and memory in real-time[10]. Xcode is build on top of open source tools such as GNU Compiler Collection and Subversion[12] and can also be used via a terminal as a standard UNIX command line interface.
3.1.1 iPhone Developer Program Portal
The iPhone developer program portal1 is a web portal for managing team members, certificates and provisioning profiles used for signing Applications. All applications must be signed to be able to executed on a real device[11].
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March 8, 2010 | Posted in Electronic Manual, Gadget Manual, Smart Phone, Software
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