XDCAM HD422 is pretty processor intensive to do an on-the-fly capture. Remember, the card does not do the codec compression (only some AJA cards do hardware ProRes captures). In most cases, Quicktime does the compression, so your processor may tank before you capture, and you may need loads of RAM. Not for the faint hearted. I haven't captured XDCAM HD422, but I have transcoded to XDCAM HD422, and I can tell you it's not real time. The machine really slows down.
Capture as ProRes HQ or even better, Uncompressed 10 bit 4:2:2, then transcode it to xdcam HD422.
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