The portion of the file holding the audio data. The audio data might be compressed to save disk space. The data has to be decompressed using an audio decompressor oftware component which decompresses audio. It must be designed to work with ACM or DirectShow Microsoft® DirectShow® is an extensible, filter-based framework, based on the Microsoft® Windows® Component Object Model (COM), that provides a common interface for mediaacross many of Microsoft's programming languages. Most video-related Windows applications, such as Microsoft's Windows Media Player, Winamp, and Windows Movie Maker, use DirectShow to manage multimedia content. For more information, see LEADTOOLS and DirectShow. Note that different compression methods require different decompressors. There is no universal decompressor capable of decoding all compressed streams. before you can play (hear) it.

SMPTE timecode, more properly known as SMPTE time and control code, is a series of digital frame address values, flags and additional data applied to a video or audio stream, and is defined in ANSI/SMPTE 12-1986. Its purpose is to provide a machine-readable address for video and audio. These are usually measured in seconds and they measure the time elapsed from the beginning of the file. It is a term describing the number you see on the VCR while you are playing a tape.