Is a multimedia container format from Microsoft, which stores video and audio file streams. Distinctive feature is a the lack of information on the coding data. The container defines the structure of the stream so it can, like AVI, contain videos with different codecs, as well as operate during synchronization of streams.
WavPack lossless audio compression. Note that, when converting .wav to this format and back again, the RIFF header is not necessarily preserved losslessly (though the audio is).