Here's are some suggestions to get the highest quality when using iVI for video editing (rather than for converting video for Apple devices playback) -
- On the Conversion Tab of preferences set the Conversion Quality to Highest
- On the Conversion Tab of preferences turn on deinterlace
- On the Conversion Tab of preferences select Original Frame Rate (in iVI 3.0 and later)
- On the Conversion Tab of Preferences select "Keep original date modified time"
- On the Conversion Tab of Preferences select "Keep original file name"
- On the Conversion Tab of Preferences select "New files default to Original resolution"
Also if you're only planning on using iVI to get video into iMovie and don't care about having iVI make video for other devices then the biggest difference can be made by increasing the bitrate. You can do this on the advanced tab of preferences. Setting the bitrate to 10Mb/s (from the default of 3.5) will make a big jump in quality but also file size.