S-Video to Composite

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S-video is basically just composite video, but split up into its chroma (colour) and Luma (brightness) parts, which both operate at different bandwidths. The pin allocation is like so:

  • 1 - ground
  • 2 - ground
  • 3 - luma
  • 4 - chroma

It comes in a horrible format from computer graphics cards, and other consumer devices. This isn't really useful for YSTV, so we have a few ways round using it:

  • The kramer convertor. This device is the preferred solution. The kramer converter performs Automatic gain control on the chroma and luma, based on the size of their respective sync pulses, before combining them. This solves many odd syncing issues with equipment.
  • The bodge cable. This is a direct join of pin 3 to 4, and then 1 to 2. This means that no AGC is done, and the output signal isn't amplified to the correct level. The 3/4 mix goes to composite signal, and the 1/2 mix goes to composite ground.
  • The less bodge cable. This method is the same as the bodge cable, but first, chroma (pin 4) passes through a capacitor of 0.4nf to 1nf, before joining to the luma signal. This, in theory, stops any interesting termination problems from appearing, although, in practice, we haven't noticed any difference when compared to the basic bodge.

As always, when using bodge cables, please test them first, as the plastic s-video connectors aren't the most sturdy things around...