Toshiba Questions?
Dear Gary: I have a Toshiba 57HX81 rear-projection TV and also a Toshiba SD-4700 progressive scan DVD player. I know with an interlaced signal you set the 3:2 detection switch to film, but what would it be set to for a progressive DVD signal? Thank you!
Tim Goodwin
mailto:tim.goodwin@cfsan.fda.gov
Video Technical Editor Greg Rogers Comments:
There is no need to set a “3:2 detection switch” when a TV receives progressive video, because the DVD player will have already deinterlaced the video. If a TV has such a switch it applies only to processing interlaced video. The setting will be ignored when receiving progressive video. There are two types of 3:2 sequences involved in converting interlaced video to progressive video, so perhaps that is generating some confusion. When a DVD player outputs progressive scan video signals it has already detected the 3:2 pulldown sequence of video fields that were created in the telecine process to convert film to interlaced video. A progressive-scan DVD player reassembles the interlaced video fields into progressive video frames that correspond directly to each original film frame. Those progressive video frames are initially at a 24 frame-per-second rate because that is the film frame rate. But your TV requires progressive video at a 60 frame-per-second rate, so the DVD player creates a new 3:2 sequence of progressive frames by alternately repeating each frame either two or three times. The 3:2 sequence that must be detected to convert interlaced video to progressive video is the first sequence of interlaced fields. The final 3:2 sequence is made up of progressive frames and the TV simply displays them in the order they are received. There is no need to detect this sequence. For more information about the telecine and deinterlacing processes, read my review of the Pioneer Elite DVR-7000 DVD Recorder in Issue 60, May, 2002.
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