Is de-interlacing *always* required for PAL DVDs?

[pgroves]

Hi - I'm using the latest version of DVD2SVCD with a registered copy of the TMPGEnc Plus encoder and was wondering if de-nterlacing is *always* required for PAL DVDs or only for certain types of DVDs (if so, which ones?). Or (as almost all my DVDs will be PAL), should I just leave de-interlacing (telecide?) switch on all the time?

regards

Paul

[setarip]

The following information, regarding the two types of pAL videos you may encounter, appears on the VirtualDub site (It appears to indicate that most commercial PAL videos should NOT require deinterlacing):

"Deinterlace - PAL movie
In PAL, two kinds of video exist:
50fps video with half vertical resolution and
25fps video with full vertical resolution
Both of these are usually captured as 25fps full resolution video which means that for 50fps video, each frame will consist of two subframes, or "fields". When these fields are merged into the full frame, interlace lines appear where the fields differ (usually due to motion). For this kind of video you should NOT use this deinterlacer. You need to use a "real" deinterlacer such as the area based deinterlacer below. You can also split the frames into their subframes and double the frame rate in which case you won't need to do any deinterlacing at all. But I recommend that you use my field shift filter below if you do this.
If, on the other hand, you have captured video with real 25fps (such as most PAL movies), there should be no interlace lines, since the fields belong to the same frame. However, sometimes the capture card gets it wrong and merges fields that should belong to different frames. This can easily be corrected by delaying all frames by one field which is exactly what the PAL movie deinterlacer does. This reconstruction is completely non-destructive. You should, however, always make sure your codec compresses the fields individually if you have this problem. Because interlace lines don't compress very well. MJPEG codecs usually have this option.
This filter needs to be first in the filter chain and before any clipping."

[sneglen]

You shall almost never de-interlace PAL DVD's unless it is a show of some sort. If it is filmed with a Television camera then it should be de-interlaced, but if it is a Movie then you should not. Movies are almost always progressive frames.