Zektor ProAudio 16™ DSP Preamp Audio Matrix - Manual (Page 29)

ClarityAudio Serial Protocol, Version 1.01, 11/8/12 27
Audio Control
@ zone = One (or more) zones to be affected.
delay = Lip sync delay in 48KHz samples, each count delays audio by 1/48000 of a second.
A value of 0 indicates no delay.
There are two forms of the lip sync delay commands, the ‘LSZ’ command which sets lip sync delay on
a zone by zone basis, and the ‘LSI’ command which sets delays on a input by input basis. Which one to
use depends on what is causing the video delay, and where it’s connected in the video path.
If the input of a video processor (or monitor) that adds a video delay is connected to a zone, then the
‘LSZ’ command should be used to delay the audio by the same amount of time the video is being
delayed. Only audio that is being sent to the video processor, attached to the zone, will be delayed.
If on the other hand, if the output of a video processor that adds a video delay, is connected to an input,
then the ‘LSI’ command should be used. This allows all zones that connect to the video processor, to
have their delays automatically adjusted to compensate for the processor’s video delays.
Both inputs and zones can have delays set, however the overall delay cannot exceed 8191 counts (or
170.65mS). If an input and zone combination exceeds 8191 counts, no error will be generated and the
delay will be set to 8191.
‘LSZ’ Examples
The lip sync delay is given in samples of a 48KHz clock, or 48 counts per millisecond. To delay the
audio by a given number of milliseconds, take the number of milliseconds, multiply by 48, and use that
as the parameter for the command. For instance to delay zone 3 by 24mS: 24mS * 48 = 1152
^LSZ @3,1152 -> Delay zone 3 by 1152 samples (24mS)
Another common timing to apply to lip sync delay is video frame times. Most video processor delay
video by a set number of frames, matching audio to video in these cases is done by delay audio by the
same number of frames. For instance 1080p60, is 60 frames per second, while 1080p24, is 24 frames
per second. To calculate the value needed to delay a set number of frame, divide the frames per second
into 48000, and multiply by the number of frames to delay. For instance if your video signal is 60
frames per second, and you want to delay zone 3 by 2 frames: (48000 / 60fps) * 2 = 1600
^LSZ @3,1600 -> Delay zone 3 by 1600 samples (two 60fps frames)
^LSZ @2,+800 -> Add one 60fps frame of delay to zone 2
‘LSI’ Set Lip Sync delay for an Input
Each input is capable of delaying audio for up to 170.65mS. The delay resolution is 1/48000 of a sec-
ond, or 48 counts per millisecond.
Command format:
^LSI @ in,@in,delay Set the lip sync delay an input or inputs.
^LSI @ in,+step$ Add ‘step’ to input’s delay.
^LSI @ in,-step$ Subtract ‘step’ from input’s delay.
Response Strings:
^=LSI @ in,delay$
Where:
@ in = One (or more) inputs to be affected.
delay = Lip sync delay in 48KHz samples, each count delays audio by 1/48000 of a second.
A value of 0 indicates no delay.