What is PAL?
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.
Did you know?
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.
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.