.W64 File Format

Introduction

Wave64 is an audio file format from Sonic Foundry and later Sony, made to get past the 4 GB limit of WAV. It holds the same kind of audio, usually uncompressed PCM, described by the same format structure, but it is a separate format with a container of its own: every chunk ID is a 16-byte GUID and every size is 64-bit. Files use the extension .w64.

A WAV reader cannot open a Wave64 file, and the explorer on this site does not read it. The EBU’s RF64 solves the same problem while staying close to WAV.

Structure

The file is one outer chunk holding further chunks. Each chunk starts with a 16-byte GUID and a 64-bit size, and unlike WAV the size counts the 24-byte chunk header as well as the data. Chunks are aligned to 8 bytes, as FFmpeg reads them; another description gives the older one-byte pad after odd chunks, so sources differ.

The GUIDs, as the bytes appear in the file:

Each GUID starts with the four letters of the WAV chunk it stands for, so the file begins with the bytes of riff in lower case, not RIFF.

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