The just:out Playout Engine supports following codecs and containers:

Codecs	Containers
DVCPRO, DVCPRO50, DVCPROHD, DV, DV Stream, DVCAM, HDV All Apple ProRes Codecs, ProRes 4444 ¹ XDCAM HD/ES/EX (1080i and 720p) MPEG-2 , MPEG-4, H.264 All AVID LE/PE codecs AVC-Intra JPEG IMX Apple Animation Codec ²	mov, mp4, m4v mpg, mpeg, mpegts avi 3gp f4v dv mkv mxf

¹ Embedded alpha information is properly sent to the Video card (fill and key).
² Apple Animation Codec is deprecated. If you need alpha we recommend to use Apple's ProRes 4444 codec.

Features

Mixing Videos with different pixel sizes in the same Playlist.
Mixing all supported codecs in the same Playlist.
Mixing Videos with different aspect ratios in the same Playlist.
The field order will be inverted automatically if needed. This can be overridden per clip with the Invert Fields function in the Inspector.
When removing frames using QuickTime Player you need to export the Video as a new file after that.
You can set new in- and out-points using the QuickTime Player's trim function.

Limitations

Not all functions coming with a certain container or codec can be used.
You cannot play Videos created with more than one codec. Make sure that all Videos are created using a single codec.

Using MXF Videos

just:out provides the technology to play out MXF wrapped Videos. However, to be able to preview such files on the operating system level or to be able to preview/set a new in/out-point or poster frame within the just:live/just:play user interface, an MXF importer from Apple may be required. Make sure to buy one license for each machine running the just:live/just:play user interface if the decoder provided by TOA does not allow you to preview the Videos in the TOA user interfaces or in case you would like to preview them in the operating system.
Due to the way MXF works, it can take several seconds to open an MXF Video, depending on its length and the number of Audio tracks coming with the Video. This implies that the readout of metadata in the Library of the just:live/just:play user interface as well as adding such a Video to the rundown will not happen instantly (as opposed to other containers).