What is WAV?

How WAV Works

WAV is an application of Microsoft's Resource Interchange File Format (RIFF), a generic chunk-based container in which every piece of data is wrapped in a "chunk" that carries a four-character identifier and a length field. This design is what makes RIFF, and therefore WAV, easy for software to parse: a program reads the four-character code to learn what a chunk contains, reads the length to learn how many bytes to consume, and then either processes or skips the chunk before moving to the next one. A reader that does not understand a particular chunk can step over it cleanly rather than failing, which is why WAV files have stayed readable across three decades of software.

A minimal WAV file contains just two meaningful chunks inside the outer RIFF wrapper. The first is the fmt  chunk, which is the technical description of the audio: the sample rate (how many times per second the waveform was measured, such as 44,100 Hz for CD audio or 48,000 Hz for video), the bit depth (how many bits encode each sample, typically 16 or 24), the number of channels, and the byte rate. The second is the data chunk, which holds the actual audio samples, almost always as linear PCM (Pulse Code Modulation), the raw, uncompressed numeric values of the waveform itself.

Because the fmt  header can in principle reference codecs other than PCM, WAV is technically a container rather than a single codec. In the real world, though, "a WAV file" almost always means uncompressed PCM audio, which is exactly why the format is treated as the gold-standard working copy in audio production: there is no decoding step, no compression artifacts, and every sample sits in the file exactly as it was recorded.

History and Standardization

WAV was defined jointly by Microsoft and IBM around 1991, introduced alongside RIFF as part of the multimedia extensions that brought sound and video to early versions of Windows. At the time, the personal-computer industry needed a simple, openly documented way to store digital audio that any application could read and write, and RIFF's chunked structure, itself modeled on the earlier Interchange File Format used on the Amiga, provided exactly that. WAV became the default sound format of the Windows ecosystem and, through it, a de facto standard far beyond Microsoft's own software.

Its straightforward, lossless storage made WAV a durable standard in professional studio production and broadcast, where preserving every sample matters more than file size. To serve those industries, the European Broadcasting Union extended the format into the Broadcast Wave Format (BWF), which adds standardized metadata and timecode chunks on top of an ordinary WAV. BWF lets a recording carry the exact time it was captured, scene and take information, and a documented history of edits, which is essential when audio from many sources has to be synchronized in film, television, and radio post-production. Crucially, a BWF file is still a valid WAV, so ordinary players can open it even if they ignore the extra chunks.

That backward compatibility is the reason WAV has outlived nearly every audio format of its era. New codecs have come and gone, but because WAV stores raw PCM in a trivially parseable container, it has remained the lowest-common-denominator format that every operating system, editor, and digital audio workstation can open without plug-ins or licensing.

Sample Rate, Bit Depth, and File Size

Because WAV stores audio uncompressed, its file size is entirely predictable: it is simply the sample rate multiplied by the bit depth, multiplied by the number of channels, multiplied by the duration. A minute of CD-quality stereo audio (44,100 Hz, 16-bit, 2 channels) works out to roughly 10 MB, and high-resolution masters at 96,000 Hz and 24-bit are several times larger again. There is no quality setting to trade off, because there is no compression, the only levers on size are the sample rate, bit depth, and channel count you choose at capture.

This predictability is a feature for professionals. An engineer always knows exactly how much storage a session will consume and never has to worry about a lossy codec quietly discarding detail between edits. The cost is sheer volume, which is why WAV is used as the editing and archival master while a smaller format like MP3, AAC, or FLAC is generated for distribution.

Limitations

WAV's biggest technical constraint is a direct consequence of its 1991 design. Because the RIFF chunk-size fields are 32-bit, the total size of a classic WAV file is effectively capped near 4 GB. For most uses that ceiling is irrelevant, but it becomes a real problem for long high-resolution recordings, a multi-hour multichannel session at 96 kHz / 24-bit can hit the limit, at which point the recording silently stops or splits. The industry works around this with the RF64 and BWF 64-bit extensions, which replace the 32-bit size fields with 64-bit ones while keeping the rest of the format intact.

The second limitation is simply the flip side of WAV's strength: it carries no inherent compression, so its perfect fidelity comes at a substantial storage and bandwidth cost. Sending a WAV by email or streaming it over the web is impractical compared with a lossy file a tenth of the size and no audible difference on typical playback. WAV also has weaker, less consistent support for embedded metadata such as cover art and tags than formats like FLAC, which is another reason it stays in the studio rather than in a portable music library.