WAV 64 bit (RF64) is extended format of wav file.
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".
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.
1) Create WAV 32 bit file which contains:
JUNK-chunk (empty or dummy 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.
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.
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.