Usually the final output for the Digital Intermediate or master timeline is for the data or image sequence to be ‘filmed out’ to a master negative, from which the prints for the Cinema release are struck. In the past everything would be taken from this negative, via the telecine and output to several different mediums, such as DigiBeta and other deliverables.
However what the DI lab has allowed is with careful workflow, a huge percentage of the output deliverables for today’s markets can be struck from the Master 2K/4K timeline. Applying different LUTs (see Calibration) for different media output you can derive your (SD) standard definition and (HD) high definition formats from the one DI master timeline.
A range of versions can be struck for the many different markets and countries that the project may be sold too. It used to be a very costly additional procedure having to produce the different versions usually employing another colourist to transfer to tape and then a second transfer through standards conversion to adjust format ratios and frame rates. Plus this in turn causes a generation loss on tape because of the compression hit going to tape. All different formats also have their own particular colour space which needs matching to best represent these different display characteristics. An SD monitor is different to an HD monitor, which in turn will be different to the look of a projector for D-Cinema.
As the DI system has the entire material stored at its highest quality, it makes sense to derive these outputs from the master making it a cost effective and an efficient solution. Many systems will be able to do these processes either in real time or as a separate rendered version. Either solution is fine as long as the correct deliverables are ordered. These are usually outlined within the contract as to what your DI house can and will deliver.
When outputting or compiling material for the different iterations, you need to have the correct speed and pitched shifted audio supplied from the audio house to match the different outputs. Film is 24 frames per second and your master timeline usually will be supplied with a 24 audio track 5.1 surround sound preferably. Sometimes it will be at 25 frames per second and the reverse procedure will need to happen to the sound for the film negative.
When film is output to PAL for instance, traditionally the telecine has always just sped the film up by 4.1%, transferring the film frame for frame, thus the people speak slightly faster and the film runs slightly shorter than the original. It is an accepted standard and recognised as the correct procedure for the transfer. However within the DI environment this no longer seems acceptable and a separate audio track is preferred with the correct audio pitch shift to counter act this 4.1% change in speed!
Alternatively when output to NTSC, which is 30 frames per second, what is known as 3:2 pulldown is inserted into the imagery to effectively stretch it from 24 to 30 fps. This involves combining frames to make extra frames. For every four film frames, five video frames are created, a way of remembering how the sequence works, the first frame is known as the A frame and if frozen on a single transferred frame the output will be still, still, flicker, flicker, still. The flicker frames are made up of combined B/C fields and C/D fields, when viewing you can notice the combined frames. If the transfer of the rushes is in 3:2 and is used for editing, the editor either has to reverse the sequence, removing the inserted pulldown sequence, or adopt a fifth frame edit mentality. Otherwise when you conform at 24p the edited frame can be a frame out either side because you can only use a true film frame - A, B, C or D.
3:2 Pulldown - 24p frame conversion to 30 fps interlaced
Pan & Scan
Pan and scan is one method of adjusting widescreen formats so that they can be shown within the proportions of a standard definition 4:3 aspect ratio television screen, often cropping off the sides of the original widescreen image to focus on the composition's most important aspects. Some film directors and film enthusiasts disagree with pan and scan cropping, because it can remove up to 45% (on 2.35:1 films) of the original image. The composition of a shot can seriously change the dramatic emphasis of a shot if cropped or adjusted. Imagine the wide expanse between gunfighters, if you place the 4:3 aspect box in the middle, you will cut off the fighters either end of the frame – however if placed on one gunfighter and then cut to the other as close-ups severely altering compositions and therefore dramatic effects.
Alternatively think of the opening of the Magnificent Seven, a generation grew up only ever seeing it on a 4:3 TV screen, having never seen it in the Cinema never actually realising the opening was of all of the Magnificent Seven – maybe the title should have been re worked for the TV version – “The Magnificent Four and a Half!”
For decades, televisions only had a 4:3 aspect ratio where the width is 1.33 times the height. When television first started to become popular, the motion picture industry had to devise strategies to give the audience something they would not get on television. Thus, "widescreen" was invented, and film images became longer, rectangular projected images with an aspect ratio greater than 16:9. Film widths are often 1.85, 2.35, or 2.39 times the height of the image, though there are other less common ratios as well.
To broadcast a widescreen film for TV, or create a DVD master, it is necessary to make a new version from the original film. One way to do so is to make a "letterbox" print, which preserves the original theatrical aspect ratio, but produces an image with black bars at the top and bottom of the screen. Another way to turn the wide aspect ratio film into a 4:3 aspect ratio television image is to "pan and scan" the negative. With the increasing popularity of HD TVs increasing, films are now starting to be panned & scanned at 1.78:1 instead of 1.33. While there is almost no loss for movies at 1.85:1, films at 1.33, 2.20, 2.35, and 2.39 still suffer from noticeable image cropping.
Pan and scan technique shown as 1.33:1 [4:3] aspect crop over Seven Brides for Seven Brothers, MGM, 1954.
For instance, in the film Jaws, the shark can be seen approaching for several seconds longer in the widescreen version than in the pan and scan version. For the opening crawl in each Star Wars film, on the pan and scan versions the viewer has to wait until a line of text of the opening crawl reaches the centre of the screen to read through that whole line. On the widescreen versions, each line of the opening crawl text appears in its entirety beginning at the bottom of the screen.
One modern alternative to pan and scan is to directly adjust the source material. This is very rare: the only known uses are computer-generated features, such as those produced by Pixar. They call their approach to full-screen versions reframing: some shots are pan and scan, while others are transferred open matte (a full widescreen image extended with added image above and below). Another method is to keep the camera angle as tight as a pan shot, but move the location of characters, objects, or the camera, so that the subjects fit in the frame.