WAV 64 bit - RF64 - MBWF

WAV 64 bit (RF64) is extended format of wav file.

Intended for:

1. Support of multichannel audio.

2. Support both more than 2 Gbyte and less file sizes.

Native WAV format support 32-bit (2 Gbyte) file size only. First symbolic sequence into WAV 32 bit file (WAV identificator) is "RIFF".

First symbolic sequence into WAV64 file is "RF64".

 

How work audio converter AuI ConverteR 48x44 with RF64

 

 

WAV file contains next chunks (information blocks):

1) RIFF-header (format identificator);

2) fmt-chunk (sample rate, channels count, sample size and etc.);

3) possible other chunks;

3) data-chunk (audio stream length, audio stream);

4) possible other chunks.

 

WAV (RF64) file contains next chunks:

1) RF64-header (format identificator, analog RIFF-chunk of WAV 32 bit);

2) dsd64-chunk (audio stream length)

3) fmt-chunk (sample rate, channels count, sample size and etc.);

4) possible other chunks;

5) data-chunk (audio stream);

6) possible other chunks.

 

Process of recording for large (more 4 Gbyte) files (according WAV RF64 specification):

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 less 4 Gbyte:

           - set up size data into RIFF, data chunks;

           - close file.

5) If recorded WAV-file more 4 Gbyte:

- replace RIFF-header to RF64-header;

- replace JUNK-chunk to 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 used as synonymous.

 

Converter compatible

AuI ConverteR 48x44

48x44's PRO and PRO Lite capable to read RF64 or RIFF (32-bit) and convert with automatical selecting format of audio file by its size.

Players compatible

foobar2000

 

WinAmp

 

 

Samples

mono

stereo

multichannel 5.1

multichannel 7.1

 

Example

When convert sample rate (see here - planned option (release soon) of AuI ConverteR 48x44) of wav-file changing of output file size (relative to input file).

For upsampling: input file (wav 32 bit or RIFF) have sampling rate 44 kHz and size 2 Gbyte. Make conversion to 176 kHz. Output file have size 2 * (176/44) =8 Gbyte. Output file must have format wave 64 bit or RF64.

 

---

References

1. EBU Tech 3306 - MBWF / RF64: An Extended File Format for Audio

2. EBU Recommendation R111-2007 - Multichannel use of the BWF audio file format (MBWF)