Part I

Latency in Live Video Production is important to understand, as the effects of being unaware will lead to challenges and dissapointment.

How many times have you seen the effect where the persons voice is not in sync with the lips on the screen?   There is nothing more distracting in a show than to watch a singer on the large screen where this synchronization is missing.

In the analog days latency was never an issue.  With the move towards digital production, latency has become a reality and something that must be factored into the equation when doing IMAG.

The argument has been presented on many discussion boards that latency of up to 6 frames in the NTSC world is acceptable.  Respectfully, that’s too long in my opinion.  I try to minimize the amount of latency in our live productions to fewer than 4 frames.

Latency occurs in all installations and this includes analog and digital productions.  However, in the Analog world the latency is so minimal it’s not even considered a challenge.  To circumvent any problems of live video production image / audio syncing,  ColossoVision has developed a latency report for all of our live video productions.  This  is now a standard part of our production when selecting equipment for your event.

Latency occurs when there is a short delay between the audio signal and video due to anolog to digital conversions, format conversions, buffering, digital signal processing, and other electronic processes.   This latency can be minimized and controlled by selecting the right equipment and designing a system which takes into account each components specifications.

Latency is also cumulative.  Every piece of equipment that undergoes signal conversion or processing has some delay.  Every component in the chain adds latency, even the camera. The question is, to what degree can it be controlled.  How much latency are you, or your client willing to tolerate.   From my experience, many clients won’t tolerate a high degree of delay.

Other items in the live production chain which can add to the Latency are

• Scalers
• Media Servers
• Digital Distribution Amps  ( VGA,DVI, and others )
• Format Convertors
• Wireless equipment

Although some of the above items may have minimal delays for the video signal,  the total delay of all of the components is what you must consider and be aware of.

Continued in Part II