Engineering Design NIDisk Podręcznik Użytkownika Pobierz pdf (Strona 13)

DartDisk User Guide

Playback Parameter Screen

The Playback parameters screen allows the user to specify the file to be played, triggering

mode and optional alarm sounds. Other parameters such as duration, sample rate and number

of channels are predetermined by the sound file. The playback file may be a 1- or 2-channel

SIGNAL or Wave file. Wave files must be stored in uncompressed 16-bit coding (0 offset,

±32768 range), which is the "PCM" or "type 1" standard

Wave file format.

Filename specifies the name of the file to be played, including file extension (e.g., myfile.1

or myfile.wav). If the filename does not include a full path (drive letter and directory), files

are played from the directory containing DartDisk. Embedded spaces are allowed in the

filename.

DartDisk accepts SIGNAL integer-format files and Wave files, but not SIGNAL floating-

point format files. SIGNAL files are strongly recommended.

• SIGNAL files are played at their original voltage range, using a conversion factor

stored in the SIGNAL file header.

• Wave files are played using an assumed voltage range of ±3 Volts (the default for

Wave hardware), which may or may not be the original voltage range of the data.

To perform a multi-channel playback, submit a multi-channel SIGNAL or Wave sound

file. SIGNAL 5 is required to write multi-channel SIGNAL files.

Dart model specifies the Dart model installed in the current system, according to its

maximum sample rate of either 50 kHz or 44.1 kHz. See "Sample rate selection" below for a

list of the sample rates available for each model. If the sample rate of the specified sound

differs by more than 1 Hz from one of the available sample rates, DartDisk will allow the

user to either proceed at the nearest sample rate or abort the playback. DartDisk does not

convert the signal's sample rate – it simply plays the sound faster or slower than its native

duration. The RESAMP command in SIGNAL performs high-quality mathematical sample

rate conversion.

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Engineering Design NIDisk Podręcznik Użytkownika Strona 13