Straight info about DVDs, and TV standards

[Peter van der Linden]

Here's the straight info on DVD, NTSC and PAL.
There is only one DVD format used for commercial video.  The video 
files on a DVD are stored in MPEG-2 digital format.  The files are 
encrypted, region locked, and with a macrovision degraded signal.  The 
MPEG-2 video
encoding on DVD is independent of PAL/NTSC protocols.

However some DVDs have the MPEG2 video signal optimized to be easily 
converted to 525lines/60Hz analog video as used in the US under NTSC.  
On other DVDs, the MPEG2 video signal is optimized to be easily 
converted to 625lines/50Hz analog video as used in the UK under PAL.  
So for practical purposes, you can consider that the tv standard 
(NTSC/PAL) is a parameter of a DVD.

Players sold in PAL countries (like the UK, Asia or Australia) can 
usually play either kind of DVD, often converting the MPEG2 into a PAL 
output signal.   When playing a PAL DVD, the player outputs a signal 
with 625 lines-per-frame, at 50 fields-per-second, with PAL color 
modulation.  When playing an NTSC DVD, the player outputs a signal with 
525 lines-per-frame, at 60 fields-per-second, and also using PAL color 
modulation (sometimes called "Pseudo-PAL" or "PAL-60").  Naturally, the 
color modulation is done by the player itself, since there is no "PAL" 
or "NTSC" in the MPEG encoded image.

Virtually all late-model PAL TVs can accept such a "Pseudo-PAL" signal. 
  Other PAL-country players handle NTSC DVDs a little differently.  They 
may output a "true" NTSC signal, which has NTSC color modulation rather 
than PAL color modulation.  Still other players allow you to select 
which type signal is output.

Players sold in NTSC countries (e.g. the US) can usually only play DVDs 
which have the MPEG2 optimized for NTSC.  So for maximum playability, 
you want NTSC discs.  On the other hand, the graphics card in your Mac 
doesn't care about the NTSC/PAL optimization of the MPEG-2 stream. Your 
Mac doesn't use crummy old tv technology to put pixels on the screen, 
and it will happily render either format.  You can thus use the video 
out signal from your Mac as a convenient format converter.

Bottom line: the MPEG video on a DVD is stored in digital format which 
will play on any PC, but is formatted for one of two mutually 
incompatible television systems: 525/60 (NTSC) or 625/50 (PAL/SECAM). 
Therefore you can consider that there are two kinds of DVDs: "NTSC 
DVDs" and "PAL DVDs." Discs are also coded for different regions of the 
world, so try to buy a player that doesn't enforce this anti-consumer 
limitation.

      Peter