Video Sync

Video synchronization is an analog signal which is used to sync a number of video signals together. This method is used in all methods of transmittion. black and burst is the SD sync. this signal contains the sync and colour burst information that is displayed at the start of any active video information. different video signals will have a differnt start of active video time when using vision mixers transistions each picture will be placed at different points of the screen as in fig 1. the other sync is tri-level sync. the name tri meaning that there is three level of sync but without the colour burst as with black and burst. Tri level is the only HD signal which is analog and be seen on an analog waveform monitor as seen in fig 2. A little useful information for SD an active video line takes 64uS.

fig 1.

fig 2.

 

 

When using multiple cameras the problem that you will find is that each camera will be timed from SAV (start of active video) to EAV (end of active video) this is the information that will be displayed on the screen. when on air the cameras will go through a video router/switcher inorder to switch between the two or more cameras to see different locations. So when a defaul tri level sync or black and burst get put in with the signal this corrects all timing for each camera. Each transition now will be smooth and with no error. Also the timing can be changed in respect so that it matches the TLS/BB input to the micro second. This is needed as the timing signal might endure some lag in processing, so will still keep a little out of time. this is not noticalbe in SDI but we need everything to be perfect for broadcast. This will help lessen any future faults and fault findings.