CWAV File

What are CWAV files and how to open them

Are you having problems opening a CWAV file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CWAV files.

What is a CWAV file?

CWAV files have multiple uses, and CompressWave Audio is one of them. Read more about the other uses further down the page.

CompressWave Audio

CompressWave Audio is a proprietary compressed audio format used in certain Japanese doujin and indie games during the late 1990s to early 2000s. It stores musical tracks or sound effects in a form that reduces file size via compression, then expands to 16-bit stereo PCM at playback. The format supports both mono and stereo input, sample rates of 44100Hz or 22050Hz, loop points, and metadata such as track title and artist within its header. It was created by the author known as Ko-Ta, who released a CompressWave library (CompressWaveLib.pas) and tools under names like CompressWave.zip.

Playback involves reading a header section containing channel count, sample rate, bit depth, a 256-entry differential conversion table, and Huffman code configuration. The compressed audio data uses Huffman-coded ADPCM, with specialized routines for reading bit-streams, setting up Huffman trees, applying adaptive differential compression, and decoding sample blocks possibly with looping. Mono files are output as duplicated stereo channels. In some builds, 22050Hz content is upsampled or filtered to produce output aligned with stereo PCM buffers.

Files of this format begin with an ASCII signature at the start of the file: the bytes "CmpWave" at offset zero. This signature is followed by a little-endian 32-bit integer for channel count (1 or 2), then sample rate, then bit depth, then the diff table, loop information, title/artist text fields, then the Huffman table and finally the compressed sample data.

How to open CWAV files

Important: Different programs may use files with the CWAV file extension for different purposes, so unless you are sure which format your CWAV file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: September 19, 2026

All known file formats using extension .CWAV

While CompressWave Audio is a popular type of CWAV-file, we know of 2 different uses of the .CWAV file extension. Different software may use files with the same extension for different types of data.

Nintendo 3DS Binary CTR Wave Audio

Nintendo 3DS Binary CTR Wave Audio files store audio data used in Nintendo 3DS software, especially for sound effects and music. They use a proprietary wave-based structure derived from Microsoft's WAV format but tailored for the 3DS's hardware. These files support multiple audio encodings including uncompressed (8-bit and 16-bit PCM) and compressed (DSP-ADPCM and IMA-ADPCM), and they can mark loop points so a section of audio plays repeatedly.

Creation of these files happens during the game development process within the 3DS toolchain. Audio is authored or converted into this format so the 3DS system can load, decode, and play it directly from storage. After being deployed (for example in game ROMFS or theme packages), the files are read by the system's audio playback engine, which interprets the headers, determines the encoding and sample rate, applies any loop settings, and outputs the sound.

Internally the file begins with a CWAV header (magic bytes ASCII "CWAV"), followed by structured blocks for INFO (which include fields for encoding type, loop flag, sample rate, loop-start and loop-end frame, channel info and encoding-specific parameters) and DATA (the actual audio samples), roughly analogous to "fmt " and "data" chunks in RIFF WAVE format.

Byte signatures include the ASCII string "CWAV" at offset 0, "INFO" at offset 0x40, and the presence of "DATA" identifying the data block.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

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