This article is a continuation of Understanding Audio File Formats (Part 1)
Ogg Vorbis (.OGG)
In addition to MP3, you may have heard of the Ogg Vorbis audio file format. It's a fairly new type of file format that does pretty much the same thing as MP3, but some say it provides better quality and smaller file sizes.
Like the Macintosh AIFF, the NeXT/Sun audio file format is also a standard format, but it's for the NeXT and Sun Sparc station computer systems rather than the Mac or PC. This format supports many types of audio data, including 8-bit and 16-bit, monophonic and stereo. It also provides support for a variety of compression schemes, but Sound Forge only supports the most common (u-Law) compression for this format. If you download a lot of audio files from the Internet, you'll file many of them with the .AU file extension. Most of these files are 16-bit audio that have been compressed to 8-bit u-Law data for transferring over the Net or for use in Java applications.
If you spend any time surfing the Internet, you've more than likely heard of this file format. The RealMedia file format creates streaming audio and video files for transmission over the Internet. It supplies sophisticated proprietary compression features for making it possible to transmit audio and video data over the Internet (even through a lowly telephone connection) in real time. This means that you can start listening to or viewing the data as it downloads rather than having to wait for the whole file to be stored on your computer's hard drive. The RealMedia format was created by RealNetworks.
Sound Designer 1 (.DIG/.SD)
Yet another product-specific format, the Sound Designer 1 audio file format is for use with the Sound Designer 1 software application on the Macintosh. And it only supports 1 6-bit monophonic audio. The files have either a .DIG or .SD extension.
Video for Windows (.AVI), QuickTime (.MOV), MPEG-1 & 2 (.MPG)
Believe it or not, in addition to audio data, Sound Forge loads and saves video data in the form of AVI, MOV, and MPG files. You can't edit the video data, but you can edit the audio data stored within a video file. AVI, QuickTime, and MPEG are special digital video file formats specifically designed for working with video on computers. Each format uses its own unique compression scheme to achieve video quality as good as possible in a file size as small as possible. AVI (Audio Video Interleaved) is a Windows-based format, which means that any computer running Windows can play AVI files. QuickTime is a Mac-based format, which means that any Macintosh computer can play QuickTime files. With special players' software, a computer running Windows can also play QuickTime files. MPEG (Motion Picture Expert Group) is a more advanced format that sometimes requires special hardware for playback. Sound Forge can both load and save all of these file types, but the MPEG formats require an additional purchase.
Microsoft Wave (.WAV)
Like MP3, Wave is another very popular audio file format that you've probably heard about. Wave is a Windows-based format, which means that any computer running Windows can play Wave files. The format supports a lot of different types of audio data, including 8-bit and 1 6-bit, monophonic and stereo audio. The Wave format also provides support for a huge number of different compression schemes, including many of the different ADPCM variants via the Microsoft ACM (Audio Compression Manager). The ACM is a part of Windows that works transparently, providing access to any compression schemes that are installed on your computer. Windows ships with a number of different schemes, and you probably also have a number of others from audio product manufacturers. If you're working with Windows, then you probably use the Wave format for about 90 percent of your audio work. Most sound and music software on the Windows platform support this format. Wave files have a .WAV file extension.
Windows Media Audio/Video (.WMA/.WMV)
Similar to RealMedia, Windows Media Audio/Video is a special audio/video file format that creates streaming audio/video files for transmission over the Internet. The format is a Windows-based format, which means that any computer running Windows (with the Windows Media Player installed) can play Windows Media files. Like RealMedia, Windows Media Audio supplies sophisticated proprietary compression features that make it possible to transmit audio/video data over the Internet in real time. And also similar to RealMedia, the compression does affect the quality of your audio/video data. Windows Media files have .WMA (audio) and .WMV (video) extensions.
RAW File (.RAW/*.*)
RAW audio format files (as the name states) contain plain audio data. The data is not saved in a specific format (like those mentioned earlier). When you save a RAW file, the audio data is saved in a "plain brown wrapper," so to speak. It's pure audio data. And when you load a RAW file in Sound Forge, you must specify certain parameters for the data to be loaded.
Perfect Clarity Audio (.PCA)
In addition to all of the aforementioned audio file formats, Sony also provides its own format called Perfect Clarity Audio. Similar to MP3, Perfect Clarity Audio uses compression to create small file sizes, but unlike MP3, the quality of the audio is not affected. Perfect Clarity Audio is known as a lossless audio file format, which means there is no loss of quality when audio is saved to this format, even though the file size is smaller than if you had saved the same audio data to the WAV file format. This is a nice way to store audio data in a limited amount of space without having to worry about affecting the quality, but keep in mind that only Sony products support this format. So, you still need to store your data in another format if you want it to be accessible from within other audio applications. In addition, because it is a lossless format, Perfect Clarity Audio can't create the same small file sizes as the MP3 format can. Either way, there is a tradeoff between file size and audio quality.
For more information:
* Understanding Audio File Formats (Part 1)
* The Sony Sound Forge Power! Books Series
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