PAL (Phase Alternating
Line) is the colour encoding conversion standard
that is used in much of Europe, Africa, Asia, Australasia
and the Middle East for television, video and DVD
playback. It was invented by Walter Bruch at Telefunken
AG in Germany during the 1960's.
PAL uses a screen resolution of 720 x 576 pixels
and has a refresh rate of 25 frames per second. In
comparison, the rival and older NTSC standard (used
primarily in North and South America and Japan) uses
a lower resolution of 720 x 480 pixels, but a higher
refresh rate of 30 frames per second. In essence
then, PAL has a better picture quality than NTSC,
but NTSC has smoother pictures, particularly when
using high speed footage.
Due to the way in which PAL signal conversions occur,
it generally has better colour quality and consistency
than NTSC, although the actual colour range is slightly
less.
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When films for the cinema are shot, they
are actually recorded at 24 frames per second
and this is the frame rate that is used in
cinemas. When these films are converted to
DVD using the PAL format of 25 frames per
second, they are simply sped up by 4%. This
means that both the footage and the soundtrack
play 4% faster (and the soundtrack is a slightly
higher pitch - two thirds of a semitone)
than when shown at the cinema. If you compare
DVD play lengths to cinema play lengths then
you can see the difference in runtimes. |
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If you are producing a DVD in the
UK that has been taken with a video camera purchased
in the UK for example, then the camera will almost
certainly have captured the video using the PAL resolution
and frame rate settings. This should be fine for
any of the markets that use PAL (click
here for a list of countries that use PAL),
but if you plan on selling the DVD in America for
example then you may wish to convert the video feed
to the lower resolution and higher frame rate employed
by NTSC. However many modern DVD players will play
and convert both NTSC and PAL DVDs and will also
play DVDs that may have specific regional encoding,
helping to avoid the regional problems created by
the different formats and specifications.
Converting PAL video to NTSC involves
adding extra frames into the footage and this can
result in slight judders during fast movement scenes
when done by most basic home editing software (Linear
Interpolation). However by using Inter-Field Interpolation
or Adaptive Motion Interpolation techniques, the
inserted frames are averaged from the frames before
and after the point where they are inserted and result
in much smoother playback.
PAL broadcasting for television purposes in the
United Kingdom is to be abandoned by 2012, being
replaced by digital DVB-T.
Find out more about the NTSC
standards.
View other CD
and DVD production FAQs.
