Field Order
INTERLACING AND FIELD ORDER
Dennis Hlynsky
Faulty interlacing creates edges that look like they have been combed with a fine-toothed comb.
WHAT IS INTERLACING
In the early days of television the inside of the TV tube was coated with phosphor. When struck by electrons the phosphor lit up. This created a small point of light. This stream of electrons was directed across the screen by a set of electromagnets. The electron stream varied according to image brightness. The phosphor was a slow to discharge and so stayed lit until the scan reached the bottom of the screen. The second pass…. The lower field scanned in-between the lines of the upper field. Thus this type of imaging is called interlacing the fields.
interlacing from DHlynsky on Vimeo.
interlacing from DHlynsky on Vimeo.
Once digitized the upper and lower field designations are removed with the sync signal. DV and HDV are interlaced formats. Programs will default to the proper format if the program can read the meta-data. Shooting 24p and recording to HDV tape will introduce "pulldown" as well as field order. Expect all American tape formats to be interlaced.
Often it is your responsibility to set the field order when rendering.
Remember
HDV is UFF or (upper field first)
SDV is LFF or (lower field first)
High Definition Video is upper (high is upper)
Standard Definition Video is lower (standard is lower than high)
Interlaced video is displayed in Editors as single fields
To make the editing interface interactive many programs will only display one field. This results in a unexpected output renders. For instance; cutting at the exact end of shot will look good in the timeline but include a lower field first flash frame in the render.