Whether interlaced video fields form a progressive video frame can be automatically determined. The presence or absence of a first characteristic of one or more video fields can be determined by analysis of the fields and/or related information such as flags, cadence, previous determinations, and others. Similarly, the presence or absence of a second characteristic can be detected. In accordance with the detecting, how likely or whether the two or more video fields form a progressive video frame can be determined based on a possibly predetermined likelihood that fields of progressive video frames in general have or do not have the first characteristic and based on a possibly predetermined likelihood that fields of interlaced video frames in general have or do not have the second characteristic.