Dlmrec - Townshend Computer Tools DAT-Link User Manual

DLMREC(1)

NAME
dlmrec – record data from multiple DAT-Links.
SYNOPSIS
dlmrec [ –N numUnits ] [ –c numChannels ] [ –u unitSpec ] [ –p precision ] [ –i source ] [ –n nsamples ]
[ –I ] [ –f format ] file
D ESCRIPTION
dlmrec records digital audio data from multiple DAT-Link devices. Although multiple invocations of
netaudiod(8) and narecord(1) can achieve the same effect, dlmrec is optimized for data throughpu
a nd also sets up the DAT-Links for correct synchronization.
If the DAT-Link+ is used, then the Sync connectors of each DAT-Link+ should be wired to an externa
c lock generator (Part EXTCLK). This allows the units to be synchronized such that each DAT-Link+
will start recording at the same time. If the incoming digital audio streams are also synchronized, the
t he data retrieved by dlmrec will remain exactly synchronized for the entire recording. Otherwise, it
can only be guaranteed that the data from each DAT-Link starts at the same time, +/- one sample.
T he output is stored in a packed format with the data from each DAT-Link interleaved. The output
begins with the left channel data from datlink0 and ends with the right channel data from datlinknn
w here nn is the number of DAT-Links.
By default the output file will consist of a 512 byte header followed by the data from each DAT-Link
interleaved on a block-by-block basis. The header contains the size of the blocks, the number of chan
n els, and a magic number for identification.
OPTIONS
–N numUnits
Specify the number of units to record from. DAT-Link devices 0 through numUnits-1 are
used. If none of the -N, -u, or -c options are specified then 4 units are used. The maximum
n umber of units that can be supported depend on the host speed and the SCSI I/O bandwidth.
Typically 4 units is the limit, giving 8 channel record capability at 48,000 samples/second
T he default is 4 units.
–c numChannels
Specify the number of channels of recording desired. DAT-Link devices 0 through numChan-
nels/2 (rounded up) are used.
–u unitSpe c
Specify the DAT-Link units to use for each channel of recording. The unitSpec argument is a
comma-separated list of DAT-Link unit numbers followed by one of the letters: L, R, or S
T hese signify left, right or stereo respectively. The order of the list determines the mapping of
channels to DAT-Link units. For devices used in stereo mode, the left channel always precedes
t he right channel. 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
C hannel 2 - right input of unit 3
Channel 3 - right input of unit
–p precision
Specify the number of bits/sample to be transferred from the DAT-Link. The default is 16
bits/sample. The precision must be a multiple of 4.
–n numsample s
Transfer numsamples samples to file and then stop. Normally, transfers continue until the user
interrupts dlmrec. Note that recording is done in multiples of an internal buffer size, thus
s lightly more than numsamples may be recorded.
–i input_source
D AT-Link Reference
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Last change: 1995/07/29
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