Engineering Design NIDisk Guia do Utilizador descarregar pdf (Página 6)

SIGNAL/RTS APPLICATION NOTES

2 Application Note 5

and binary coding, or headerless, i.e., with no header at all. SIGNAL can read and write

binary sound files in headerless format or with SIGNAL, Wave, and AIFF headers. The RTS

can read sound files with SIGNAL, Wave, or BLB headers, and can write sound files either

headerless or with SIGNAL headers. Header-based files may require programming to

enable exchange between systems, while headerless files are a default format for exchanging

sampled sound data. However, file information such as sample rate and binary coding must

be provided to the file-reader in order to interpret the headerless data. The SIGNAL header

structure is the subject of this note.

Sound File Structure

SIGNAL sound files consist of two parts, a header section and a data section. The header

section contains information about the file and its contents: file size, data representation

(integer vs. real), buffer type (T, F, FT), sample rate, etc. The header mixes ASCII and

floating point (real) data, and can be extended by the user to add demographic information or

notes about the data. The data section contains the sampled waveform, power spectrum, or

spectrogram, and is written in binary format, without record marks or other dividers. Data

may be represented in either integer or floating-point (real) format. RTS sound files are

identical, except that they only contain integer, time data.

Terminology

The following terms are used in this note:

• 1 File Block = 512 bytes in length

and can contain: 128 4-byte (32-bit) real numbers

256 2-byte (16-bit) integers

512 1-byte ASCII characters

• 1 Header Element = 4 bytes

and can contain: 1 real number

4 ASCII characters

• Abbreviations:

elt = element

< > = blank

N = numerical header element = 4-byte real number

I = numerical header element = 4-byte integer number

L = literal header element = 4 ASCII characters

1 2 3 4 5 6 7 8 9 10 11 ... 33 34

Sem comentários

Engineering Design NIDisk Guia do Utilizador Página 6