Bu Ering Of Audio Data; Customizing The Con Guration - Townshend Computer Tools DAT-Link User Manual

5.13 Bu ering of Audio Data
5.13 Bu ering of Audio Data
This section describes how the
formation may be useful in some interactive applications where it is important to
control latencies when sound les are played back. It may also be necessary to
modify the bu er settings to avoid underrun errors when transferring audio les
across a network.
DAT-Link
The contains an internal bu er of approximately 2 Mbytes that is used to
bu er audio data sent from the host computer. This bu ering is necessary to allow
the host computer to be used by multiple users and tasks without creating gaps
in the playback. It does, however, occasionally create some delays and unexpected
behavior.
When the host computer begins sending audio data to the NetAudio server for
DAT-Link
playback, the
audio outputs. It instead stores the data in its internal bu er. Playback does not
actually commence until one of the following situations occur:
1. Enough data for one second of playback has been transferred. The amount
of bu ering may be changed by using the
Section 5.14.
2. The host computer nishes sending the audio data.
Once playback begins, the host computer must continue to send audio data to the
DAT-Link
suciently quickly to keep the bu er from becoming empty. If the bu er
drains completely before the host computer is nished playing back a le, an error
is returned and playback is stopped. Gaps will never be inserted into the playback.
The bu er utilization can be monitored by the
Section 10.2.
The main e ect of the bu ering on
0.5 seconds between the time the
begins. The actual delay time depends on the speed of the host computer, the SCSI
bus transfer speed, and the network load if the
remote machine.
For applications where ner control over the bu ering is required, custom programs
can be written using the subroutine library described in Section 12 and Appendix
G.
5.14 Customizing the Con guration
Many of the command line options, as well as additional options can be speci ed in
.datlinkrc
the users le in their home directory. The format of this le is described
DAT-Link
bu ers audio data internally. This in-
does not immediately begin sending the data to its digital
nastatus
is that there is a delay of approximately
naplay
command is issued and when sound output
naplay
option described in
bufferTime
command described in
command is issued on a
naplay
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