WAVE
An audio file container built on RIFF structure, commonly used to store uncompressed PCM but also able to hold floating-point PCM, compressed audio, and extended channel information.
Explanation
WAVE (Waveform Audio File Format) is an audio file format defined by Microsoft and IBM on top of RIFF (Resource Interchange File Format), commonly using the `.wav` extension. Files consist of chunks identified by four-character codes: a RIFF header declares the WAVE type, the `fmt ` chunk describes audio encoding and parameters, and the `data` chunk holds audio data; other chunks may record broadcast metadata, sampler information, markers, or additional notes.
WAVE is a container, not a synonym for PCM. The most common WAVE files store integer linear PCM, but the `fmt ` chunk can also identify IEEE floating-point PCM, ADPCM, A-law, μ-law, and other encodings through registered format codes. The WAVE_FORMAT_EXTENSIBLE extension can specify effective bit depth, channel mask, and subformat, addressing limitations of ordinary WAVEFORMATEX for high bit depth, multichannel, and complex formats. Seeing only a `.wav` extension cannot guarantee 44.1 kHz, 16-bit, or uncompressed audio inside.
Classic RIFF uses 32-bit unsigned fields for chunk length, so a single file's representable size is near the 4 GiB limit. Broadcast and production systems developed extensions such as RF64 for long, multichannel, or high-sample-rate recordings, using special length markers and additional data chunks to store 64-bit sizes. Wave64 is another extension structure, not identical to RF64 or ordinary RIFF WAVE.
WAVE's chunk design lets applications skip unrecognized additional chunks, but software compatibility still depends on chunk order, alignment, encoding codes, and extension support. Broadcast WAVE (BWF) adds production metadata such as description, time reference, origin, and loudness on top of compatible WAVE; audio data may still be PCM. RIFF INFO, ID3, or custom blocks written by tagging software are not interpreted by all players.
Saving lossless PCM as WAVE is usually convenient for editing and exchange, but file size is larger than lossless compression formats such as FLAC and ALAC. Both can contain the same samples after correct conversion; container choice does not automatically change sound. Conversely, decoding lossy audio to WAVE yields only uncompressed decoded results and cannot restore information already lost from the original recording.