Sppack; Multi-Channel File Formats - Townshend Computer Tools DAT-Link User Manual

B.1 Audio Data File Formats
B.1.8 SPPACK
SPPACK is a signal-processing system used at AT&T Bell Laboratories. Files can
be read or written in this format using the
or . Only 16-bit, linear encoding is supported.
narecord
B.1.9 Multi-Channel File Formats
The and
dlmrec dlmplay
two channels of data. These programs use les stored with the multiple channels
interleaved either on a sample or a block basis. The sample-interleaved format
stores the data packed, most-signi cant-bit rst, with no header, and the samples
organized as follows:
L 0 R 0 L 1
0 0 0
j
where is the -th left sample from
L j
i
sample.
The block-interleaved format has a 512 byte header with the following structure:
struct BlockHeader {
unsigned int magic;
int nchannels;
int bufsamps;
int precision;
int filler[124];
};
#define MAGIC_BLOCKHEADER 0x424c4b45
All variables are stored using the host byte-order although the data is most-signi cant-
byte rst. The magic number identi es the le as a block-interleaved le;
is the number of input channels that were used to make the recording;
speci es the number of samples that are stored from each
ing to the next unit, and
Starting at byte 512 of the le, the rst
unit 0 are stored with the data packed. The left and right samples are stored
sample-by-sample interleaved. Following this is the data from unit 1, unit 2, etc.
until the rst samples from all
bufsize
repeats until all samples are stored.

sppack

programs deal with digital audio data with more than
R 1 L 2 R 2 L 3 R 3 L 0 R 0 L 1 R 1
0 0 0 0 0 1 1 1 1
DAT-Link
+ unit
/* Magic number (MAGIC_BLOCKHEADER) */
/* Number of audio channels in file */
/* Number of samples in each block */
/* Precision of samples in bits */
/* Make it 512 bytes */
is the number of bits/sample.
precision
bufsize
units is stored. The sequence then
nports
setting of the option to
-f
: : : L 2 R 2 L 3 R 3
N N N N
j
and is the
j R j
i
/* "BLKE" */
nchannels
bufsamps
DAT-Link
before advanc-
DAT-Link
pairs of samples from
125
naplay
(B.1)
-th right