Broadcasted movies and interlacing

[reepa]

I just recorded Star Wars from a local channel #2. Anyway, the movie doesn't seem to be interlaced. In high motion scenes I see no weaving artifacts. The only time when I see weaving is when the subtitles (in Finnish) appear and disappear. Is this because of the way the film is scanned into an analog format (where both fields are exactly the same)? If so, wouldn't that mean the movie only has a vertical resolution of half the PAL vertical resolution (576/2=288)?

[neuron2]

The fields are not exactly the same. They are spatially offset by one line. But they are taken from the same moment in time. Thus, there is no combing because there is no relative motion between the fields (same moment). There is full resolution because all the lines have unique content corresponding to image detail. Such frames are called progressive. But the subtitles are rendered at field rate, which means the fields are sampled at different moments. Then the field-rate subtitles are overlayed on the progressive movie.