How are NTSC TV shows converted to PAL?

[Gameshow Host]

Today for the first time I tried capturing an american TV show that had been converted to PAL for my country. I wouldn't normally do this, I was just getting some quick screen grabs.

Anyway, when I looked closely at the image I noticed that the image was interlaced perfectly. Meaning that each field was crisp and sharp. And then it occurred to me I have no idea how NTSC TV shows are converted to PAL (or vice versa).

I understand how the fps can be changed, by using telecine-like methods of messing with the fields, or cutting out fields altogether - but I don't understand how an NTSC image (with 525 lines) can be converted to a PAL image (625 lines) and the fields remain intact!

Obviously scaling has to take place somehow. But how can an image that is made up of lines with gaps between them - be scaled to fit into a new image with a different number of lines with gaps between them?

Anyone know, or care to guess?

[ironwood321]

Some american shows are recorded onto film which is 24fps and its not to difficult to change them to 25fps without encountering 3:2 pull down. You might see more of this 3:2 pull down effect if you capture an american show in america.

Just an idea.

[Gameshow Host]

Hmmm.

I know that many TV shows are shot onto film. But I assumed that once that film is transferred to NTSC for showing on American TV, the film is never used again and any PAL conversions are taken from the NTSC recording, and not the original film.

I thought this because when I watch ANY American TV show (I live in the UK) it is blurry. I have always assumed it is blurry because it has been stretched from the NTSC version. Now if the PAL version was taken directly from the film, then the PAL version would look crisp and high resolution, like normal PAL programmes. But I've never seen anything American that looks crisp and high resolution. Never.

So I think that any PAL conversions are always taken from the NTSC TV video itself, and not from original films. Taking it from the original films would involve re-editing the whole thing, surely.

I'm a little bit worried about this issue actually because I always buy all my American TV shows from America so they're region 1 and I'm getting the NTSC original. I don't want to buy region 2 version because (I assumed) that they are just transferred from the NTSC version, and hence lower quality. But if the PAL versions were taken from the film, and not from the NTSC video; then by buying the region 2 version from my local shop - I'm actually getting a higher quality version than the Americans who made the show! But that would only be true of shows shot onto film. To be honest, I can't always tell which shows are on film and which are on video, cos all American TV shows look blurry.