Ideally we like to add an extra device to an editing system for two reasons:
1. To playback your edits onto a proper video monitor, rather than rely on the "preview" quality display from the graphic card.
2. To let you capture video through analogue, HDMI or SDI.
Playback to a TV or video monitor
EDIUS can play back video full screen on a computer monitor without any additional hardware. Modern graphic cards will let you have 3 monitors attached so you could conceivably have two screens showing the EDIUS interface and a third with a full screen playback of the video, however, this will always be the playback of a graphic card rather than a proper video image. The image may sometimes "tear", the colour and brightness levels will differ from a proper video device and it will always be a progressive picture.
A better way is to add additional hardware which will let you see a proper video image on a TV or monitor. Grass Valley make some of their own cards and also support third party devices from Blackmagic, Matrox and AJA. Matrox devices only work with EDIUS if you use the Windows 7 drivers. The Windows 8 drivers will cause EDIUS to crash. This will not be fixed so you would only use a Matrox device with EDIUS if you already own one. AJA devices are limited to preview only currently. Support for capturing footage should be added at a later date. For these reasons Blackmagic are the most popular devices for use with EDIUS.
EDIUS will talk to DV and HDV cameras via a standard FireWire. It can also output more in real time at full quality through FireWire than any other editing program. Capture is in either HD or SD depending on the format. Realtime output through FireWire is always only SD.
For analogue, HDMI & SDI you will need to add am i/o card. These cards will normally also output video for you. Blackmagic tend to be the most popular since they are inexpensive and work well. There are advantages to use, for example, a Matrox MXO2 with some programs, such as Premiere Pro, but with EDIUSMatrox and Blackmagic have the same abilities. Grass Valley cards are the best "quality" in terms of build but cost considerably more than Blackmagic devices so most uers tend to buy Blackmagic.
The most popular card is the Blackmagic Intensity Pro 4K which handles component, composite, SVIDEO and HDMI in and out and outputs at video resolutions of up to UHD. It also has a Time Base Corrector built-in which can "clean up" bad signals and let you capture video off old decks that would not work on other devices. Blackmagic also have a range of devices which are PCIe, USB3 or Thunderbolt. Of these the USB3 versions have been slightly "problematic" with EDIUS.
You can read more about the Blackmagic range of i/o cards here: http://www.dvc.uk.com/acatalog/Black_Magic_capture_cards.html
The Grass Valley cards are also available. Click here for full information on these cards.