Best Practices – Digital Asset Guidelines – Rev 4 www.autocare.org | www.autocarevip.com | technology@autocare.org 31 7.4 Audio Formatting As is the case with video, there are multiple audio formats to consider when formatting your source audio files. The table below lists some of the more popular audio formats: Audio Format Format Description Audio Interchange File Format (.aif) Apple format, not supported by all web browsers or all platforms. Waveform Audio (.wav) Microsoft, lossless, developed for PC, large file sizes. MPEG-1 Audio Layer 3 (.mp3) Compressed wav file (1/12th the size), compresses data at a constant bit rate. Windows Media Audio (.wma) MP3 format for Windows Media Player, compressed three times more than MP3s. Ogg Vorbis (.ogg) Open source, more compressed than MP3, variable bit rate compression not accepted by many audio software. Advanced Audio Coding (.aac) Logical successor to MP3 for medium to high bit rate audio – advanced ways to compress audio. Pulse Code Modulation (.pcm) High fidelity, uncompressed digital sampling of an analog audio signal. AC3 Audio (.ac3) Known as Dolby Digital this format is being replaced by AAC. Musical Instrument Digital Interface (.midi) MIDI files are extremely small and are supported by many different software applications and Internet browsers.