Alofi(1) Alofi(1)
NAME
Alofi - a network-transparent audio server for LoFi
SYNOPSIS
The AF audio server is a network transparent system developed at Digital
CRL for using LoFi audio hardware in a distributed environment.
DESCRIPTION
Alofi is an AF server with LoFi/DECaudio device dependent support.
STARTING UP
Alofi [:portOffset] [options] &
OPTIONS
-help
Use the help switch to determine device independent arguments.
-device device
Specifies the name of the LoFi audio device. If this switch is not
used, the Alofi audio server will default to the device specified by
the AUDIO_DEVICE environment variable or the /dev/lofi device. (In
general, /dev/lofi is a symbolic link to the /dev/lofi0 device special
file.)
-ukernel lodfile
Specifies an alternate DSP56001 absolute lodfile. If ukernel is not
specified, the server checks for the AF_UKERNEL environment variable.
If neither the switch nor the AF_UKERNEL environment is used, the
server looks for the path DIR/main.lod (Or DIR/mainteleport.lod in
-teleport mode) where DIR is the LODPATH environment variable if it
exists, otherise it is the config variable LODDIR.
-pcoeff coeff_file
Specifies an alternate set of X filter coefficients for the
primary/phone CODEC. coeff_file should be an ASCII file containing
eight lines with two bytes per line representing the X filter coeffi-
cients for the AMD79C30A CODEC. Here are the contents of an example
file containing the default coefficients used on LoFi's telephone
CODEC.
94 0F
C2 AC
94 FF
22 AB
36 EA
4A B2
A4 E2
BC BA
-teleport
When this switch is specified, the operation of the hifi parts of the
server are customized to work well with the Ariel Teleport DSP port to
telephone interface. In this mode, device 2 is a 16 bit mono path to
Line 1 of the Teleport and device 3 is a 16 bit mono path to Line 2 of
the Teleport. On device 2, the passthrough mode controls the "line"
or "local" setting of the local telephone set. Device 2 also provides
two "inputs". Input 0 connects the interface to the telephone line,
while Input 1 connects the device to the Teleport local battery cir-
cuit. Along with -teleport, you must specify "-mode ext" "-hrate xxx"
and "-dspc xxx".
The Teleport mode replaces the low two client data bits on output with
inband signalling to the Teleport. On input, the low two bits are
inband signalling from the Teleport, which are observed, but not
changed by the server.
-nohifi
Disables HiFi support (devices 2, 3, and 4).
-daa_gain {0,1}
Sets the state of the telephone DAA's gain control bit. Setting the
bit to 1 (default) disables the power limiting circuitry in the DAA.
Setting the bit to 0 enables the automatic power limiter.
-mode {int,ext}
Sets the hi-fi operating mode: int selects the internal stereo DAC
(44.1 kHz, two-channel output). ext selects an external device con-
nected to the DSP port. NOTE: make sure the switch on the back of
the distribution box is set to match the operating mode. Defaults to
int.
-hrate <#>
Informs the server of the hi-fi sample rate (in samples per second).
This option does not set the rate for the hi-fi hardware. The inter-
nal DAC runs at 44100 samples per second. External devices may have
fixed sample rates, be configurable with panel switches, or may be
software configurable (see the -dspc parameter below); consult the
device's manual for details. Defaults to 44100.
-dspc <#>
Specifies a 3-bit DSP port value that sets the sample rate for some
hi-fi devices; consult the device's manual for details. Only valid
when the external operating mode is selected.
AUDIO DEVICES
The Alofi audio server presents five audio devices to client applications.
These audio devices are the 8KHz mu-law telephone CODEC, the 8KHz local
audio CODEC, left and right stereo HiFi device, mono HiFi left channel dev-
ice, and finally the mono HiFi right channel device. These audio devices
have device numbers of 0 to 4. In Teleport mode, there are 4 devices, num-
bered 0 to 3.
CONNECTION NAME
From the user's prospective, every AF server has an audio connection of the
form:
hostname:portOffset
This information is used by the application to determine how it should con-
nect to the server.
hostname
The hostname specifies the name of the machine to which the audio
device is physically connected.
portOffset
The portOffset is used to identify the audio server's port on host-
name. For example, to simultaneously run two audio servers on a
given host, you might select 0 or 1 for portOffset.
If the connection name to an audio server is not specified, then the
environment variables AUDIOFILE or DISPLAY will be used.
ACCESS CONTROL
The sample server provides two types of access control: an authorization
protocol which provides a list of ``magic cookies'' clients can send to
request access, and a list of hosts from which connections are always
accepted.
EXAMPLES
Alofi has been used with the following three devices: the Ariel ProPort
Model 656, the Ariel Teleport Model 214, the Ariel DM-N Digital Microphone,
and the Applied Speech Technologies A/D16.
A "-mode ext" option selects external operation (disabling the DECaudio's
built-in stereo DAC). The "-dspc #" option sets bits on the DSP port to
set the external device's sample rate in some device specific way. The "-
hrate #" informs the server of the sample rate (the actual sample rate is
usually set by the external device).
Ariel DM-N Digital Microphone settings:
5.5 kHz: Alofi -mode ext -dspc 3 -hrate 5500
11.02 kHz: Alofi -mode ext -dspc 2 -hrate 11020
22.05 kHz: Alofi -mode ext -dspc 1 -hrate 22050
44.1 kHz: Alofi -mode ext -dspc 7 -hrate 44100
Ariel ProPort Model 656 settings:
8 kHz: Alofi -mode ext -dspc 6 -hrate 8000
11.025 kHz: Alofi -mode ext -dspc 5 -hrate 11025
16 kHz: Alofi -mode ext -dspc 4 -hrate 16000
32 kHz: Alofi -mode ext -dspc 3 -hrate 32000
44.1 kHz: Alofi -mode ext -dspc 2 -hrate 44100
48 kHz: Alofi -mode ext -dspc 1 -hrate 48000
Applied Speech Technologies, A/D16: (fixed single channel, 16 kHz input)
16 kHz: Alofi -mode ext -hrate 16000
Ariel Teleport Model 214 settings:
7.2 KHz: Alofi -teleport -mode ext -dspc 2 -hrate 7200
8.0 KHz: Alofi -teleport -mode ext -dspc 1 -hrate 8000
9.6 KHz: Alofi -teleport -mode ext -dspc 0 -hrate 9600
BUGS
DECaudio's built-in DAC will not work if there is an external device
plugged into the DSP port (regardless of the switch setting).
If you encounter a repeatable bug, please submit a problem report to () and
include the source code if possible.
SEE ALSO
AF(1), Aaxp(1), Amaxine(1), Alofi(1), Ajv(1), Amsb(1), Aj300(1), aplay(1),
arecord(1), apass(1), aset(1), abrowse(1), afft(1), ahost(1), aphone(1),
aprop(1), ahs(1), axset(1), xpow(1), afxctl(1), aname2num(1), alsatoms(1),
aevents(1), abob(1)
COPYRIGHT
See the COPYRIGHTS file.
Copyright 1991-1994, Digital Equipment Corporation and the Massachusetts
Institute of Technology.
AUTHORS
Digital Cambridge Research Lab