The best replacement for matrox is canopus.

The best alternatives to matrox are rated as following:
★★★★★  canopus
★★★★  blackmagic
★★★★  aja
★★  avid
★★  decklink
★★  eyefinity
★  cognex
★  black magic
  cineform

Your alternative for matrox is not listed? Suggest!
Speaking about matrox, one probably shouldn't forget about avid.

Other search terms related to matrox and their ratings are:
★★★★★ avid
★★★ adobe premiere
You have in mind a companion for matrox and it is not yet here? Propose!



Google Trends

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matrox
canopus
blackmagic