WAV 64 bit - RF64 - MBWF | Read Easy Explanation >

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WAV 64 bit (RF64) is an extended WAV file format. This file type has either *.wav or *.rf64 extension. Why do we need WAV RF64? RF64 samples, players, converters.

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What is WAV RF64

RF64 is intended for supporting of:

file size of more than 4 Gbyte;
multichannel audio.

Native WAV format supports up to 4 Gbyte file size only due to value size limitations (32-bit integer).

The first symbolic sequence in WAV 32-bit's file content is "RIFF". It's a WAV identifier.

The first symbolic sequence in WAV RF64 file is "RF64".

How audio converter AuI ConverteR 48x44 works with RF64

WAV 64 vs WAV RF64

WAV 64 (WAV 64-bit) and WAV RF64 are different formats.

WAV may have a bit depth 64 bit. We can call it WAV 64-bit.

Standard WAV-header fields, which are responsible for size, have 32-bit length. These fields may be replaced with 64-bit ones. That file type may be called WAV 64 or WAV 64 bit or SONY Wave64.

WAV RF64 is standard extension of WAV format. It contains special header and special rules to fill ordinary WAV headers.

WAV structure

WAV 32-bit chunks

Chunks are information blocks, that contains chunk identifier, the block size and information.

RIFF-header (format identifier);
fmt-chunk (sample rate, channels count, sample size and etc.);
other chunks are possible;
data-chunk (audio stream length, audio stream);
other chunks are possible.

See graphical WAV RF64 format structure >

WAV (RF64) file chunks

RF64-header (format identifier, analog RIFF-chunk of WAV 32-bit);
dsd64-chunk (audio stream length)
fmt-chunk (sample rate, channels count, sample size and etc.);
possible other chunks;
data-chunk (audio stream);
possible other chunks.

How RF64 works

According to WAV RF64 specification WAV files are processed next way:

1) Create WAV 32-bit file which contains:

RIFF-header;

JUNK-chunk (empty or dummy chunk);

fmt-chunk;

possible other chunks;

2) Append to end of file data-chunk. Append audio stream data.

3) End recording.

4) If recorded WAV-file lesser than 4 Gbyte:

- set up size data into RIFF, data chunks;

- close file.

5) If recorded WAV-file more than 4 Gbyte:

- replace RIFF-header with RF64-header;

- replace JUNK-chunk with dsd64-chunk with filling information about size recorded file;

- set up 0xFFFFFFFF data-chunk size;

- close file.

MBWF is RF64 file with bext-chunk. The terms "RF64" and "MBWF" can be used as synonymous.

Compatible audio converters

AuI ConverteR 48x44

AuI ConverteR is capable to read RF64 or RIFF (32-bit) and converting with automatical selecting format of audio file by its size.

Compatible audio players

foobar2000

player RF64 foobar2000

WinAmp

Player WAV 64 bit

See more players...

Download samples

See more samples in high resolutions here...

Example

When sample rate of a WAV file is changed, the output file size is altered relatively input file.

For upsampling: input file (wav 32 bit or RIFF) has the sampling rate 44 kHz and size 2 Gbyte. After conversion to 176 kHz, the output file size is 2 * (176/44) =8 Gbyte. And, output file must have format wave 64 bit or RF64 to avoid broken inner structure.