Probably the best format to use for files with embedded alpha channel for use in TriCaster are those encoded using NewTek’s own SpeedHQ 4:2:2:4 codec. This format can serve for either SD or HD clips, and represents a high quality, moderately compressed alternative. (As a registered NewTek customer, you can download the NewTek TriCaster Codec Pack for either Windows® or Mac® platforms from your personal Downloads page on the NewTek website.)
Apple® computer users have several other options available which support an alpha channel, including the Animation and PNG Quicktime® movie codecs (select “Millions of Colors +” in the codec settings to include alpha in the file).
For more information please download the entire document at new.tk/rt-m