What is Telecine Removal?

The goal of “telecine removal” is to create a resulting file that is progressive (not interlaced) and is 24 frames per second (North America) or 25 fps (Europe, Japan, Australia) regardless of whether your material was shot interlaced or progressive. 
Telecine Background (as it relates to cameras): Some cameras shoot only in interlaced mode, while other cameras have a menu choice to shoot as either interlace or progressive. But shooting progressive doesn’t mean you automatically get a 24p file from your camera. In the case of most HDV and AVCHD cameras, when the 24p mode is selected, the image sensor samples at 24 progressive frames per second, but the images are actually recorded to tape or SSD as 60i (interlace) by adding redundant fields (a process called ‘telecine’). Why do they add telecine instead of leaving the files as 24p? Well, the creators of the HDV spec never included a 1920×1080 24p mode. For 1920×1080 resolution the only frame format allowed in the spec was either 50i or 60i. So to solve the problem, camera manufacturers added telecine to turn their cinematic 24p signal into an interlaced 60i signal (yuck!). So the underlying format is 24p, but to the outside world (including editing software) the material is actually 60i. Traditionally you must edit such material as a 60i project. The problem is that edit points don’t always exist on clean progressive boundaries because of the insertion of interlace fields. So after editing, 24p material embedded in 60 can have a poor quality look – certainly not cinematic!   
The solution? Remove the telecine cadence and edit at 24p! Simple as that sounds, it’s actually somewhat complicated. But this is a process CineForm has been doing for many years, and our telecine removal algorithms are excellent. The way we do this is to read the source image and determine whether it is progressive or interlaced. If interlaced, we then determine whether the underlying cadence inside the interlace wrapper is progressive or not. Based on our algorithmic decision we choose the best telecine removal algorithm. The result is a 24p file (from 60i source) or a 25p file (from 50i source). 
Be aware: For best quality telecine removal, you should always shoot in your camera’s progressive mode if it is available. Why? If you shoot in 24p mode (even when wrapped in 60i) we can perfectly remove the redundant fields. However, if you shoot in interlaced mode you have never recorded any progressive frames, so we have to create progressive frames were none actually existed. This process works, but the resulting progressive frames are usually ‘softer’ (less crisp) than if you shot in a 24p mode originally.

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