Autodesk 62205-051408-9001 User Guide - Page 596

21 Using Filters order is usually determined by the hardware (video card) used to digitize the footage. Note: When working with interlaced footage, view your clips on a television display whenever possible for the most reliable results. There are three options for interlaced video frames: upper field first, lower field first, and no fields. Upper Field First Upper field first means that the first horizontal line, and every other subsequent line, comes first in time (before the second line and every other subsequent line). Upper field Lower field Complete frame Lower Field First Lower field first means that the second horizontal line, and every other subsequent line, comes first in time (before the first line and every other subsequent line). No Fields No fields indicates that each video frame is a complete image frame. For example, certain types of video cameras can use progressive scan mode (whole frames are captured rather than fields). Also, computer-created and animated images can be rendered with no fields. Note: Sometimes, you may receive interlaced footage that has been scaled or manipulated without any field separation. This often results in irreparable field problems. In such cases, you usually need to go back to the source footage. Use the following table as a guideline to the most common field orders for interlaced video. Format DV 640 x 480 NTSC 648 x 486 NTSC Full 720 x 480 NTSC DV 720 x 486 NTSC D1 768 x 576 PAL 720 x 576 PAL DV 720 x 576 PAL D1 HDTV First Field Order Lower Upper Upper Lower Usually lower Upper Lower Upper Upper or lower (no fields if progressive scan) Once you select a field order and the fields are no longer visible in the image, you should test how the moving image looks as you advance through the clip. Any moving objects in the clip should move smoothly and in the right direction. If moving objects appear to move back and forth or jitter, the field separation setting is wrong. You may receive video footage that is marked "odd" or "even" field first. Usually, the upper field is referred to as the "odd" field (containing lines 1, 3, 5, and so on), and the lower field is referred to as the "even" field (containing horizontal lines 2, 4, 6, and so on). Some products, however, specify the first line as 0 (an even number) and some specify the first line as 1 (an odd number). Therefore, be sure to test the footage to ensure the correct field order is selected. Note: If your footage appears to have some interlaced frames and some complete frames, then the footage probably originated on film and was transferred to video using pulldown. For more information, see "Removing 3:2 Pulldown" in Chapter 4, "Building Workspaces''. When playing back or exporting to interlaced video, make sure the field order you specify matches the receiving system. Otherwise, motion may appear stuttered, and edges of objects in the frame may break up with a comb-like appearance. 580