Audio File Format Specifications

File Description: SPPACK file
File Extension: Commonly .d
File Byte Order: Big-endian or little-endian

Prof. Peter Kabal, MMSP Lab, ECE, McGill University: Last update: 2017-01-20

SPPACK File Specifications

SPPACK files were in use at AT&T Bell Laboratories. In addition to sampled data, they can store frequency domain and quefrency domain data. Peter Kroon (now with Intel Mobile Communications) maintained a signal processing library and promoted the use of this format.

File Header

The file header is 512 bytes long. SPPACK files contain single channel or stereo data. Normally, the data is in big-endian byte order, but there is some indication that little-endian SPPACK files have also been used.

Offset ength Type Contents
0 80 character Comment string
80 80 character Comment string
160 80 character Command line
240 2 integer Domain: 1 - Time; 2 - Frequency; 3 - Quefrency
242 2 integer Frame size
244 4 float Sampling frequency
248 4 character -
252 2 character File magic: 0x40C3
254 2 integer Data type: 0xFCOE for sampled data
256 2 integer Resolution: 8 or 16
258 2 integer Companding: 1 - 16-bit integer; 2 - -law; 3 - A-law
260 80 character Text string
340 80 character Text string
420 80 character Text string
500 2 integer DAT-Link information: Magic: 4567
502 2 integer Left-channel flag
504 2 integer Right-channel flag
506 6 character -
512 - samples Audio data


Sample File

addf8.d (47 kB)
SPPACK file, 16-bit data, 8 kHz sampling rate