Townshend Computer Tools DAT-Link - 5.11 Channel Status and User Bits; 5.12 Starting and Stopping the DAT Machine

58 Playback Tutorial
data to be connected to the naplay program without creating an intermediate le.
For example, if sine is a program which generates a sampled-data sine-wave, then
a test tone can b e output on the left channel using:
sine | naplay -ol
The playback will continue until either the sine program stops generating data or
the program is interrupted. Note that the -r , -t , and -R options are not available
when standard input is used.
5.11 Channel Status and User Bits
In addition to audio data, the connection between the DAT-Link and the digital
audio equipment also carries some additional information known as channel status
bits and user bits . By default, naplay zeroes all of the user bits and generates
channel status bits for that are appropriate for the chosen values of the other options,
assuming a consumer digital audio device is connected. If you are using professional
equipment with the AES/EBU connectors on the DAT-Link , then naplay should
be given the -A option. This causes some subtle mo dications to the channel status
bits that are required by the professional standards.
For users that wish to exercise greater control over the channel status and user bits,
naplay has an option, -c , which instructs it to read the control information from
a le. This le can be edited using any text editor. It's format is describ ed in
Appendix B.4.
5.12 Starting and Stopping the DAT Machine
The naplay program also provides an option that allows the DAT-Link to start and
stop the DAT recorder automatically. By running naplay with the -a option, the
DAT-Link will start the DAT machine recording before beginning playback. After
playback has completed, the DAT machine will be stopp ed.
Before this option can be used, it is necessary to set up the DAT-Link 's remote
control facility as describ ed in Chapter 8. Also, the DL RC environmentvariable
must be set to the name of the device to be controlled. To start the DAT machine
the naplay program issues the following remote commands:
STOP - RECORD - <6 second pause> - PLAY
Between the RECORD and PLAY commands, the six second pause gives the DAT
machine time to enter record mode. When playback is nished the program issues
a STOP command.