Why is there a delay when using the Live Video feature?

Applicable SongShow Plus Versions:
This article applies to all versions of SongShow Plus.

When video is being streamed from a source, sent through DirectShow to SongShow Plus then to the display, there is a delay that takes place.  This delay is significant enough to make any situation requiring live video to be synchronized with audio impractical.  

The most likely cause for this delay is that the computer has to process the video stream through software means which adds a time delay.  IMAG equipment handles this video stream processing at a hardware level and is much faster. 

To further complicate matters the DirectShow capture process was designed for capturing video and audio to be stored on the hard drive.  In this situation, complex algorithms are used to ensure that these two elements stay synchronized in the destination file.  This synchronization process, however, is useless in a live situation since the audio signal is not passing from the speakers microphone, into the computer, then onto the sound board.

This is not just a SongShow Plus issue.  This issue is noticeable when previewing video using Movie Maker.  Other presentation packages available on the market have this same problem.

This problem exists for any input device: USB, USB 2.0, IE 1394, internal cards.

At this point PC hardware is not yet up to the task to replace a video switcher in a live production setting.  This should be made clear to users who are hoping to use the video device support for such a purpose.

Having said that, there are still uses for the Live Video ProModule in services.  Situations where audio synchronization is not necessary will work fine.  This can include using a live setting as a background for songs or scripture (such as a camera focused on a candle), or video images of crowds, and even performers, where the video is not the subject but rather a backdrop.

(MI001)