Audio Delay Control
Note: Audio is an option and may not be fitted.
Proteus contains an audio delay, which comes after the audio source selection point.
All selected audio channels are delayed equally. Depending on the standards
conversion mode, various options are available.
Tracking Delay
When the input line standard and output line standard are the same, Proteus enters
synchronisation mode. Normal synchronisation action will give occasional video frame
drops or repeats as the input video frame rate slides through the output video frame
rate (which is normally locked to reference). In this case it is appropriate to enable
tracking delay since the video delay will vary from 0ms to 33ms/40ms for 525/625 line
systems. This will give discernible lip-sync errors if the audio does not track these
delays. It is important to note that additional block delay can be superimposed on this
tracking delay to accommodate further upstream audio/video misalignments.
Fixed Delay
When the input line standard and output line standard are different, Proteus enters
standards conversion mode. The standards conversion process gives a fixed processing
delay of 33ms/40ms for 525/625 line systems (this delay refers to the input line
standard). In this case it is appropriate to enable fixed delay mode and to dial up the
appropriate delay according to the input line standard. Additional block delay can also
be added to further accommodate upstream audio/video misalignments.
Jumping or Ramping to Target Delay
When a new delay is selected, there will inevitably be a small disturbance to the audio
signal if the system ‘jumps’ to this new target delay. To alleviate this, Proteus
incorporates a ‘ramp’ option that permits the target delay to be reached over a
number of seconds. The compromise is that during the ramping time, lip-sync will be
misaligned. Note that ramping is not available for the extended audio option.
Minimum Delay
Please note that the minimum audio delay through the unit is 5ms.
Ensuring the menu button is extinguished, press the shift+chroma buttons. The
characters “Block Delay Adj” will be displayed and the menu button will now light.
The rotary encoder will now allow cycling through the various audio delay options
available. These are as follows: -
“Block delay Adj” (overall audio block delay adjust 0-320mS)
“Track Delay Mode” (option to track to video delay in synchroniser mode)
“Block delay Response” (option to jump or ramp to the selected audio delay)
