Townshend Computer Tools DAT-Link - Multiple Unit Playback

9.3 Multiple Unit Playback 85
devices used in stereo mo de, the left channel always precedes the rightchannel. For
example, the string, \ 0L,3S,2R ", would create the following channel map.
Channel 0 - left input of unit 0
Channel 1 - left input of unit 3
Channel 2 - right input of unit 3
Channel 3 - right input of unit 2
9.3 Multiple Unit Playback
Similarly to dlmrec , the dlmplay program allows a multi-channel data le to be
played back using multiple DAT-Links . The dlmplay program accepts either of
the data le formats generated by dlmrec and automatically recognizes the format.
The blo ck-interleaved is preferable as it results in signicantly less CPU load since
no reorganization of data is required by the host CPU.
Synchronization of the multiple units requires that the Sync connectors of each
of the DAT-Link +'s are wired to an external clock as described in section 9.1.1.
Dlmplay then uses the external clo ck as a master source and lo cks each DAT-Link +
to the bit and word external clocks. The READY signal is then used to guarantee
that playback b egins simultaneously for all units.
When dlmplay is used with version 1.5 or older of the DAT-Link , the sampling
rates can be synchronized by connecting the word clo cks connectors on each units
together using a BNC cable. Start-time synchronization is not available on these
units.
As an example, to playback a 6-channel, blo ck-interleaved le at 44,100 sam-
ples/second using 3 DAT-Link units, you can use the command:
dlmplay -E -S 44100 filename
Note that the blo ck-interleaved le contains a header describing the number of
channels, precision, etc. so these do not need to be specied on the command line.
The -E species the use of the external clock signal.
As with dlmrec ,if any unit connected to the external clo ck is not involved in a par-
ticular command, it should b e forced ready with the help of dlmkrdy . Furthermore,
the channels can b e redirected with dlmplay 's -u option as described previously for
dlmrec .
The manual pages in Appendix G provide more information ab out the command
line arguments and usage of dlmrec and dlmplay .