field settings

[landrover]

Because of this the simplest way to determine if you have the field settings correct is to play the video back on an interlaced monitor and adjust your settings accordingly.

Yes, Doc, and that is exactly where the problem lies. Because Powerdesk features the "reverse field order on a TV"-function, I am always able to get proper playback. But if I deliver a product to a client, I want to make sure that the client will be able to properly play back the DVD or tape on his/her TV or that it can be broadcasted properly.

[Dr Mordrid]

The key then is to produce a project in distribution format to determine if its field order is correct when play on DVD/tape then use that setup from then forward.

Dr. Mordrid

[Flying dutchman]

@Dasher:

It doesn't really matter at all if you produce a DVD with field order A or B because the field order is explicitly written into the Mpeg headers so the DVD player will know what field to display first. I have produced DVD's of both field orders, even with both field orders in different clips on the same disk.

When using analog video capture, it is the *capturing* device that determines which field order the resulting video is.

Let me try to clarify the matter a little bit.

In order to understand all this, one should realize that "real" interlaced video has no field order at all. Every "top" field is preceded by a "bottom" field which is preceded by a "top" field etcetera, so which field comes first? It is fully unimportant, as long as you play them back in the correct temporal sequence and at the correct position: The top field occupies the "odd" scan lines (if you start counting at "1") and the "bottom" field occupies the even scan lines.

The field order only becomes a problem if you combine two consecutive fields into a frame. The capturing device can take an "upper" one plus the subsequent "lower"
one and combine these into a frame. Fine. That would be "upper field first". But there's another possibility that works equally well. It can also combine a "lower" one with the subsequent "upper" one. That would be "lower field first".

Now that we have two fields merged into one artificial "frame" we must remember which one was recorded first, because the two fields represent different moments in time. If your capturing device records "top field first" and your DVD authoring software treats it like "bottom field first" the result looks absolutely terrible on TV.

"Video For Windows" (VFW) had no notion about field order. AFAIK there's no flag in the AVI container format for it. The wizard in the famous tMpegenc encoder runs a short test on AVI files to pseudo-visually determine the field order, which is a brilliant idea (but sometimes it fails...). Some video editing applications even expect the footage to be in a certain field order and will produce unusable results when fed with clips in the wrong format.

BTW, it is really easy to convert a clip from field order A to B or vice versa.

If you shift the whole video clip one pixel up or down, you also swap the field order!
This trick is used by the Cinemacraft Mpeg encoder, it always produces Mpeg's of the same field order. So if you have a bunch of video that you want in the reverse field order, just load it into Virtualdub and shift the lot one pixel up or down using the "resize" filter.

[dasher]

Thanks all. Clearer now. I think