The original aim of 3:2 pulldown was to create a TV signal that could be broadcast at 60 Hz within the NTSC sector. Various player devices (DVD, HD-DVD, Blu-ray players) can carry out 3:2 pulldown independently with available film sources.
The film material used, with 24 frames per second, is segmented into a 3:2 rhythm (i.e. divided into half frames). The first full frame is divided into to half frames, the second full frame is divided into three half frames (whereby the third is a repetition of the first half frame) and the third full frame into two half frames, etc. This creates 60 half frames per second – the required frequency, which is suitable for broadcasting. This can also be described as a signal with a 3:2 cadence. The disadvantage of this processing method is that it changes the way motion is depicted because the divisional scheme is not linear. The result is some slight juddering.
Since flat screens function on a full frame basis, this type of signal must be deinterlaced before it can be displayed. Well-developed solutions recognise the cadence being played and are therefore able to restore the original full frames. The result is a judder-free 24H signal. This process is also known as “Inverse Telecine” or “Reverse Pulldown”. Unfortunately, the deinterlacers of many televisions are often not stable enough in this regard when it comes to recognising the cadence. They treat the material like video (true 60 half frames per second), so that 60 full frames per second are created (which do not achieve the original quality). Alternatively, the restored full frames are forwarded to the panel in an "unsuitable" (e.g. 3:2) rhythm to allow playback at 60Hz. In both cases, the quality og motion playback suffers.
Until now, people mainly spoke of 60Hz signals. In fact, those in the broadcasting sector work with 59.84Hz. In order to achieve this frequency, the film material is slowed to a minimum of 23.976 full frames per second by the 3:2 pulldown. This is usually the basis for NTSC DVDs as well as for the new HD media.
3:2 pulldown has not been of much importance in the PAL sector until now, since 50Hz signals are more commonly used in this sector. Here, PAL speedup is used with 2:2 pulldown. The new HD media (HD DVD, Blu-ray) represent one exception. Here, film material with 24 frames per second is saved. The player output can usually be provided at 24Hz (1:1) or 60Hz (using the 3:2 pulldown described above).