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Chapter 8: Ogg Vorbis Playback
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OVERVIEW
Two compressed audio formats down, one to go. In this chapter, you'll learn how to extend the audio engine to support the Ogg Vorbis codec. In case you haven't heard of it before, Ogg Vorbis is an open-source codec created by Xiphophorus (xiph.org). It's popular on Linux due to its open-source heritage, and is quickly gaining momentum as an alternative to MP3.
| Tip | If you do use Ogg Vorbis extensively in your game, I implore you to give something back to the Ogg Vorbis community. Open-source software is rooted in the idea that one person looks at something, makes it a bit better, then releases it as open source so that others can improve it further. Donate some money to Xiph.org, so that they can keep releasing great code, and/or donate some brainpower by contributing to the codec's development. |
The thing that makes Ogg Vorbis so great is that it's open source. The specification itself is free—you have every right to write code that reads or writes OGG files, without having to pay for a license. Also, the Ogg Vorbis libraries are available under the BSD license, meaning that you can use them in whole or in part in your own closedsource applications.Many studies, some scientific and some less so, have been done comparing Ogg Vorbis to MP3 to WMA and so on, but you'll have to evaluate each format yourself and decide which is best for you. I personally think Ogg sounds better than MP3, but people may argue that the high-school years I spent blasting Ozzy and MegaDeth have taken their toll on my audio wetware. Don't take my word for it—rip a WAV file into technically equivalent MP3 and Ogg Vorbis formats and see which one you like better.
| AUDIO CLIP | Audio Clips 8.1 and 8.2 are examples that compare a regular WAV file with its Vorbis-encoded equivalent. |
Also, you should realize that what I'm about to show you cannot be done with the MP3 file format without paying money. This chapter embeds an Ogg Vorbis decoder directly into the audio engine. MP3 requires you to pay a licensing fee to do that (we skirted the issue last chapter because Microsoft's DirectShow was doing the decoding, not us). Ogg Vorbis, on the other hand, allows you to decode the format yourself without having to pay a fee.
