What are the considerations for PCB layout, and connector selection for video signals. Is it necessary to follow 75ohm impedance criteria in a closed system. The pipeline starts at Sony FCB IX 11 A camera core which outputs VBS 1V p-p NTSC signal with no impedance specifications, goes to a processing board (TI processor based), and outputs as a same specification video signal. I do not have real estate budget to accomodate 75 ohm RF connectors in the design and was wondering if I could work with Micro D connectors, and treat video as just another analog signal. The output is not to be transmitted over lengths more than 2 feet.
For 2 feet, I believe trying 'evil' cabling and result is likley not noticable on screen. For better result, microminature coax connectors, used on Wifi, etc. tends to be 50 ohms. Although not 75 ohms, it is better than Micro D connectors.
The amount of video interference due to impedance mismatches will be strongly related to the distance between the most widely separated points of mismatched impedance.
If a composite video signal is terminated at both the source and load (with the source outputting a double-strength signal which it expects to be 50% reduced by the double termination), then one can have a single impedance mismatch or cluster of close-together impedance mismatches somewhere without visibly affecting the picture (since any signal reflected within the cluster will either die down quickly or leave the cluster, and any signal that leaves the cluster will be absorbed before it's re-reflected).
If a signal is only terminated at one end, then even a single impedance mismatch which is a significant distance from the non-terminated end may cause visible interference.
The extent to which an impedance mismatch to a video connection will affect the picture is in large measure a function of what impedance mismatches, if any, already exist.