The WAVEFORMATEXTENSIBLE data structure defines common properties of an audio stream and occurs in a variety of multimedia file formats, including:
- Microsoft Wave
- Microsoft Audio/Video Interleaved
- Microsoft Advanced Streaming Format
- Microsoft xWMA
- QuickTime container
Since the format originated on Windows/Intel computers, the defined, multi-byte numbers are stored in little endian format, even if the data structure appears in QuickTime files.
bytes 0-1 wFormat bytes 2-3 nChannels bytes 4-7 nSamplesPerSec bytes 8-11 nAvgBytesPerSec bytes 12-13 nBlockAlign bytes 14-15 wBitsPerSample bytes 16-17 cbSize bytes 18-19 wValidBitsPerSample OR wSamplesPerBlock OR wReserved bytes 20-23 dwChannelMask bytes 24-39 subFormat [given as a 16 byte GUID] bytes 40.. extradata [actual number of bytes is determined by the value of the cbSize field minus 22]
It is an extension of the WAVEFORMATEX structure, which is typically used for data with at most two channels. A WAVEFORMATEXTENSIBLE structure can be recognized by wFormat being equal to 0xfffe.