WMV files are a type of video file (usually containing audio) from Microsoft. These files can be played on a variety of video players on both Mac and PC machines. Some WMV files may have digital rights management (DRM) protection which prevents users from making unauthorized copies of files purchased in online stores.
Windows Media Video (WMV) is a compressed video file format for several proprietary codecs developed by Microsoft. These files are based on the Microsoft Advanced Systems Format (ASF) container format encoded using the Windows Media Video (WMV) codec.
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AAC is similar to MP3. It essentially cuts out, or compresses, information that the human ear cannot pick up thereby making digital files smaller and more easily managed and therefore quicker to download. AAC is about half the size of MP3 but with better quality. It is at least one tenth the size of CD digital data. Apple are the biggest users of this format and if you have an iPod or iPhone then you will have come across this format as it is iTunes default audio format.
AAC is similar in concept to MP3 but goes further. It too compresses digital audio files but to a bigger degree. It is also part of the MPEG-4 standard, it is most widely used to create small digital audio files. The current variant is specified in ISO/IEC standard 14496-3. Like MP3, AAC is a lossy algorithm. The human hearing system cannot hear quiet sounds in the presence of loud sounds of a similar frequency; for example, a voice conversation cannot be heard while an aeroplane flies low overhead. This is known as auditory masking, this allows the discarding of data with minimal loss of quality.
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A combination of Fraunhofer IIS, AT&T Bell Laboratories, Dolby and Sony Corporation