Table of Contents
Formats used for audio storage are Broadcast Wave Format (BWF), as specified in EBU Tech Pub 3285 with annexes.
Commands to the Core Audio Engine are passed by means of a TCP SOCK_STREAM connection to TCP port 5005 on the host server.
Commands have the following general syntax:
cmd-code [arg] [...]!
cmd-code
A two letter command code, describing the generic action to be performed
arg
Zero or more arguments, delimited by spaces or, if the last argument, by ! (see below)
The ASCII character 33, indicating the end of the command sequence.
Unless otherwise specified, the engine will echo back the command with a + or - before the !, to indicate the success or failure of the command execution.
Pass a password to the server for authentication.
PW
password!
password
Returns: PW +! to indicate success,
PW -! to indicate failure
Prepare an audio interface to play an audio file.
LP
card-num
name!
card-num
name
Returns: LP
card-num
name
stream-num
conn-handle!
stream-num
The stream number selected to be used, or a -1 in case of error. This is relative to the audio adapter selected.
conn-handle
The connection handle. This will be used to refer to the playback event in all subsequent calls to CAE.
Free an audio playback interface. This will also mute all associated output stream->output port volume controls.
UP
conn-handle!
conn-handle
The connection handle of the playback event, from the Load Playback call.
Position the playback pointer.
PP
conn-handle
position!
conn-handle
The connection handle of the playback event, from the Load Playback call.
position
Position in file, in milliseconds.
Play the loaded file from the current position.
PY
conn-handle
length
speed
pitch-flag!
conn-handle
The connection handle of the playback event, from the Load Playback call.
length
Playback length in milliseconds, relative to the current start position.
speed
Playback speed in thousandths of a percent. 100000 = normal speed.
pitch-flag
Controls whether audio pitch changes with speed or not. 0 = no, 1 = yes.
Stop playback of the specified playback interface.
SP
conn-handle!
conn-handle
The connection handle of the playback event, from the Load Playback call.
Prepare an audio interface to capture an audio file.
LR
card-num
port-num
coding
channels
samp-rate
bit-rate
name!
card-num
The number of the audio adapter to query.
port-num
The port number to use. This is relative to the audio adapter selected.
coding
0 = PCM16, 1 = MPEG Layer 1, 2 = MPEG Layer 2, 4 = PCM24
channels
1 = Mono, 2 = Stereo
samp-rate
Sample Rate in samples/sec. 32000, 44100 or 48000 supported.
bit-rate
MPEG Bit Rate. For PCM, this should be zero.
name
The base name of a file in the audio storage filesystem. If the file already exists, it will be overwritten, otherwise it will be created.
Free an audio capture interface.
UR
card-num
stream-num!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
Returns: UR
card-num
stream-num
len!
len
Length of recording, in mS.
Record a loaded file.
RD
card-num
stream-num
length
threshold!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
length
Length of time to record in milliseconds. If zero, record until told to stop.
threshold
Threshold of audio detected at which to start recording, in 1/100 dBFs. If '0', start immediately.
Returns: When recording actually begins, a Record Start (RS) confirmation will be echoed back. If record time expires a Stop Record (SR) confirmation will be echoed back.
Stop recording of the specified record interface.
SR
card-num
stream-num!
card-num
The number of the audio adapter.
stream-num
The stream number.
Receive-only signal to indicate recording has actually started (as with a VOX event, where actual recording may begin some time after the interface is placed into record).
RS
card-num
stream-num!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
Set the volume of an input stream.
IV
card-num
stream-num
level!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Configure an output stream to use a particular output port.
This will cause the stream-num output volume
control feeding the port-num port to be set
to the level given by level, while all other
output_volume controls for that stream to be muted --e.g. set to
-100 dB.
OP
card-num
stream-num
port-num
level!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
port-num
The port number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Set the volume of an output stream.
OV
card-num
stream-num
port-num
level!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
port-num
The port number to use. This is relative to the audio adapter
selected. If a value less than 0 is
provided, then all output ports for
stream-num will have their volume
controls set to level.
level
The level, in hundreths of a dB.
Transition the volume of an output stream over time.
FV
card-num
stream-num
port-num
level
length!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
port-num
The port number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
length
The length of the transition, in milliseconds.
Set the gain level of an input port.
IL
card-num
port-num
level!
card-num
The number of the audio adapter to use.
stream-num
The port number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Set the gain level of an output port.
OL
card-num
port-num
level!
card-num
The number of the audio adapter to use.
port-num
The port number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Set the mode of an input stream.
IM
card-num
stream-num
mode!
card-num
The number of the audio adapter to use.
port-num
The stream number to use. This is relative to the audio adapter selected.
mode
The mode, as follows:
0
Normal
1
Swap left and right channels
2
Left audio on both channels
3
Right audio on both channels
Set the mode of an output stream.
OM
card-num
stream-num
mode!
card-num
The number of the audio adapter to use.
stream-num
The stream number to use. This is relative to the audio adapter selected.
mode
The mode, as follows:
0
Normal
1
Swap left and right channels
2
Left audio on both channels
3
Right audio on both channels
Set the VOX threshold level of an input stream.
IX
card-num
stream-num
level!
card-num
The number of the audio adapter to use.
port-num
The stream number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Set the signal type of an input port.
IT
card-num
port-num
type!
card-num
The number of the audio adapter to use.
port-num
The port number to use. This is relative to the audio adapter selected.
type
The mode, as follows:
0
Analog
1
AES3 Digital
Request the status of an input port.
IS
card-num
port-num!
card-num
The number of the audio adapter to use.
port-num
The port number to use. This is relative to the audio adapter selected.
Returns: IS
card-num
port-num
status!
status
The status, as follows:
0
OK
1
No Sync
Set the gain of an audio passthrough path.
AL
card-num
input-num
output-num
level!
card-num
The number of the audio adapter to use.
input-num
The input number to use. This is relative to the audio adapter selected.
output-num
The output number to use. This is relative to the audio adapter selected.
level
The level, in hundreths of a dB.
Open an RTP channel for audio capture.
CO
card-num
port-num
udp-port
samp-rate
channels!
card-num
The number of the audio adapter to use.
udp-port
The port number on the remote system to which to send RTP packets.
samp-rate
The requested sample rate.
channels
The requested number of channels.
Returns: CO
card-num
port-num
udp-port
samp-rate
chans
pkt-size!
pkt-size
The number of bytes to send per UDP packet.
The actual sample rate and number of channels may be different from those requested; clients must be prepared to detect and deal with this possibility!
The following messages are sent by CAE to indicate current status and audio levels. They are sent to the UDP port requested by the Meter Enable ['ME'] command.
Send current meter level of output stream
ML
type
card-num
port-num
left-lvl
right-lvl!
type
Type of meter.
I
Input
O
Output
card-num
The number of the audio adapter to use.
port-num
The port number on the audio adapter.
left-lvl
Left channel level, in 100ths of dBFS.
right-lvl
Right channel level, in 100ths of dBFS.
Send current meter level of output stream
MO
card-num
port-num
left-lvl
right-lvl!
card-num
The number of the audio adapter to use.
port-num
The port number on the audio adapter.
left-lvl
Left channel level, in 100ths of dBFS.
right-lvl
Right channel level, in 100ths of dBFS.
Output play position.
MP
card-num
stream-num
pos!
card-num
The number of the audio adapter to use.
stream-num
The stream number on the audio adapter.
pos
The play position in mS.
The current output stream transport status.
MS
card-num
port-num
stream-num
status!
card-num
The number of the audio adapter to use.
port-num
The port number on the audio adapter.
stream-num
The stream number on the audio adapter.
status
Current transport status.
0
1