Multiple Unit Recording - Townshend Computer Tools DAT-Link User Manual

9.2 Multiple Unit Recording

above, the output from both units will start within one sample time of each other,
and operate at exactly the same sample rate. Note however, that until playback
begins, there will not be any output from the digital outputs. Once playback begins,
it may take a few seconds for the receiving DAT machine to lock onto the signal.
The same method can be used to synchronize recordings from multiple
DAT-Link
This version
beginning a recording. Thus, input can be synchronized by using the sequence:
naset -u foo:0 -S E
naset -u foo:1 -S E
narecord -u foo:0 file1 &
narecord -u foo:1 file2 &
naset -u foo:0 -S OG
The rst two commands will turn o the output clocks for both
they attempt to send a zero on their outputs, both units will block after the
programs are begun. When unit 0 is changed to a master clock source,
narecord
both units will simultaneously begin acquiring data from their inputs.
The above techniques can be extended to synchronize any number of
even units connected to di erent hosts.
9.2 Multiple Unit Recording
The program provides a facility for synchronizing and recording from mul-
dlmrec
DAT-Links
tiple . Although the same functionality is provided by using multiple
invocations of
netaudiod
signi cantly better data throughput. This allows a greater number of channels to
be recorded simultaneously while handling synchronization transparently.
The recorded signal from multiple
the command line, using one of two formats. The
using the option to
-I dlmrec
in the le. For example, if 4
will be organized as shown:
0 0 1
L R L
0 0 0
j
where is the -th left sample from
L j
i
sample.
The second format, which is the default, is a block-interleaved format and is de-
scribed in Appendix B.1.9. Use of this format results in signi cantly less CPU load
during recording since no reorganization of data is required by the host CPU.
For example, the command:
always outputs a zero on its digital output just before
and , as described above,
narecord
DAT-Links
is stored in a single le, speci ed on
, stores the same samples from each channel together
DAT-Links
are used for recording, the resulting le
1 2 2 3 3 0 0 1 1
R L R L R L R L R
0 0 0 0 0 1 1 1 1
DAT-Link
DAT-Links
DAT-Links
DAT-Links
can obtain
dlmrec
format, speci ed
interleaved
2 2 3 3
: : : L R L R
N N N N
j
unit and is the
j R j
i
83
.
. Since
,
(9.1)
-th right