‐Preprocessing is critical for web video, but generally it is not needed when you convert to video formats like MPEG‐2 for DVD or SVCD.
Deinterlacing video
‐The most basic and critical form of preprocessing for the web is deinterlacing.
‐Most video is produced and edited as interlaced (although, an increasing amount is done as progressive scan). But almost all web video is encoded as progressive scan.
‐If the source frame of video is left with interlaced lines intact, the output shows the stacked lines.
‐So, at the same bit rate, deinterlaced video shows fewer artifacts than interlaced video.
Understanding telecine and inverse telecine
‐ A special case of progressive scan is film source and film‐like 24P production. – Traditional motion picture film runs at exactly 24 frames per second (fps) progressive scan, which doesn’t convert to the 59.94 fps of NTSC or the 50 fps of PAL.
‐Converting from film to PAL is easy. The video is sped up 4% to 25 fps and converted into progressive PAL.
‐NTSC is a little more complex to perform. The film is first slowed down to 23.976 fps, and then it is converted to the 59.94 fps by using 3:2 pulldown.
‐The first frame of film becomes three fields of video, and the next frame becomes two fields of video, and the next becomes three fields, and so on.
‐This process results in two out of five frames having fields that come from different source frames.
‐When possible, it is best to convert to 24P on import and then do all the work on the project in 24P mode.
Cropping
‐The safe areas exclude the edges of the screen, which may be cut off or distorted on some televisions (especially older ones).
‐In some digital video editing applications, you can crop an image using a filter. In others, such as
