History of Digital Cinema in Cinema Rooms.
In relation to the analog cinema, the digital cinema is something recent, specifically near the year 2000 began to see the first digital projectors, which had a resolution of 1280 × 1024 pixels and at that time did not exist as such the format DCP. It used a server where the movie was stored, which came in several DVD-ROMs. In the US the first digital projection was “Star Wars Episode I” in just two rooms as an experiment to see if the public accepted the new format, which was so. In Spain the film “Fantasy 2000” inaugurated the first digital projections.
Between 2001 and 2005, the year in which the first DCP officially appears and the DCI consortium is formed, there are innovations in the systems of projection, storage, management, etc … defining the format to be used around the world.
In Spain it would still take time to start, not being until 2005 when the first digital rooms begin to emerge timidly. We are always talking about 2D projections, the 3D would be later, and would be the great driver of the digitalization of the rooms.
In 2007 in Spain the first digital stereoscopic projection was made, which was Beowulf. The tremendous success made other exhibitors decide to bet on digital technology and above all because of the attractiveness of 3D, and began digitizing the rooms at a really incredible rate.
We are currently on the upward curve and until at least 2013 will not be covered (in the US) 50% of digital rooms of the total. The tendency is then to go down because the main exhibit chains will be the ones that make the change faster, whereas the small cinemas will still take time to digitize, due to the costs of the process, which will decrease in time.
What is PDD? Parents of the DCP.
The DCP, which stands for “Digital Cinema Package” is, to understand, a digital version of a 35mm film.
The advantages of this format are many. The first is the physical size. Being a digital medium, a DCP fits on a hard drive and is easily transportable. A small 16GB pendrive can hold a short film, trailers, spots … nothing to do with heavy, delicate and cumbersome reels …
Then there would be the price. The whole process is digital, and eliminates many costs and problems associated with “transfer” to 35mm. Which does not mean that it is simpler, obviously. And of course there are new problems to deal with.
But, who is behind this format? There are two key agencies in this whole business. On one side is DCI , which stands for Digital Cinema Initiatives . Founded in 2002 with support from Disney, Fox, Paramount, Sony Pictures, Universal and Warner. That is, practically all the great ones. They came together to create specifications that were open to everyone so that everyone could agree. These standards were called DCI and all digital servers would have to meet them so that the contents could be reproduced without problems. DCP This format is also called ” Interop ” and was officially born in 2005.
On the other hand, it is the SMPTE (Society of Motion Picture and Television Engineers), which extends the DCI standard, although all must be compatible projectors DCI, conduct die besten Beamer im Test thesome already support the new formats that support SMPTE
In fact, the format SMPTE will be the one that is used mainly, because it has support of 25 and 30 frames per second. Remember that from the beginning, the film has ALWAYS gone to 24 images per second, something that will change radically soon, when the Hobbit is released at 48 FPS, and later Avatar 2 at 60 FPS. These two new frequencies are called box HFR (high frame rate).
DCP playback formats (video and audio).
In what is image, we have three formats both 2K and 4K, called ” Flat “, ” Full ” and ” Scope “. Each of them have slightly different resolutions.
” Flat ” is the most similar to FullHD, having a resolution of 1998 x 1080 pixels, and correspond to 1: 85: 1 35mm
” Full ” is the highest resolution format, 2048 × 1080. It is a little wider than “Flat”. It does not have an extended use.
” Scope ” It is the widescreen, 2048 × 858 pixels are and correspond to 2:35 35mm, although it is still narrower 2:39
The resolutions in the case of 4K are simply DOUBLE than those of 2K.
On the audio, it must be said that it has the highest possible quality. It goes to 48Khz and 24bit without any compression. The mix can be either 5.1 or 7.1 although the system is set up for 23.1 channels.
The DCP inside.
Although it really is a conglomerate of letters and numbers that seems to not give too much information, the truth is that behind this mishmash of information lies the information:
The two files with the extension “MXF” are the ones the projector will use to play the DCP. One contains the image and another contains the sound. The rest of the files are information about the DCP that the server needs to be able to reproduce them, in addition to saying who has made the DCP, etc.
Comparatively it is like a video file any of your computer, only that it serves only and exclusively to be reproduced in servers of digital cinema.
A DCP occupies a ratio of about 1 Gigabyte per Minute. Thus, a 90 Minutes movie will occupy approximately 100GBs. Since the compression system, based on JPEG2000 and XYZ color coding at 12 bits per component is extremely efficient, the visual result is identical to the original master.
There are two types of DCP currently, both supported: INTEROP and SMPTE .
Interop is the older format and is the most consistent of the two, as all servers must stand DCI.
SMPTE is the most modern format, which will gradually settling on all servers.
The differences between the two are the subtitling system, incompatible with each other but improved in the case of SMPTE, and in the case of SMPTE is extended to 25FPS and 30FPS playback options in addition to HFR modes. This makes it necessary to avoid touching the audio (which we will see below) to be able to go to 24FPS.
Currently, ALL commercial films come in Interop at 24FPS.
A DCP can be copied and viewed on any movie server. This is good for a trailer, ads, promos or viewing of controlled material. However when it comes to something more sensitive like a movie, you need something more.
This is where KDMs, short for “Key Delivery Message” or more commonly, the protection and control system of DCPs.
KDMs use a triple control system:
The first one applies when creating the JPEG2000 files, as we have seen before. This prevents unauthorized persons from playing the DCP on a device that is not suitable. It is possible to clone or copy it, but I could not reproduce it, because I do not have the KDM that allows me to.
The second of these is the playback control by time. This means that the DCP can only be reproduced for a certain time, as a “rental” method. Once the time has passed, the movie can not be played back until a new KDM is requested.
The third of them limits the server where it can be played. For example, the owner of cinemas can rent a copy of a movie, and thanks to the picaresque, could have the idea of copying the movie in two rooms to get more profitability. Well, the serial number protection of the server makes it not playable. Thus, KDMs offer triple protection and serve as a control mechanism.
One of the peculiarities of KDM is that they NEVER come with the movie disc. The delivery path is ALWAYS different, and is usually by email or on a pendrive we receive separately.
Said KDM gets into the server through a pendrive, which causes the movie to be unlocked and allowed to play.
DCPs typically come in two different types of storage, which are targeted at different types of durations.
The ads, the trailers and the shorts less than 10 minutes of duration, usually come in Pendrives, because they occupy little space.
On the other hand, short films that last 10 minutes, documentaries, movies … usually come in hard disks, which can be 2.5 “self-feeding, or 3.5 with its protective housing.
The action of copying the contents of the pendrive or hard disk is called “Ingestar”, which is nothing more than an automatic file copy that occurs as soon as the device is inserted through the USB port of the server. There is not much more to do in that regard.
DCI Servers (brands, features).
The DCI servers are responsible for managing the DCPs, creating playlists, and of course, sending the information to the projector. Practically all have a similar operation, allowing to ingest DCPs via USB and eSATA. They are mostly based on Linux, although some of them run under Windows.
There are mainly four brands of servers, each with its own graphical interface, but all of them compatible with the DCI standard, which are, Qube, Doremi, Dolby and GDC.
Recently, the RED company has announced its own server, called RedRay, that in addition to being able to accept DCP, uses its own format, which they say the bitrate lowers still maintaining the original quality. It promises to give a good blow to an industry where prices are not exactly economic.
2D and 3D projection.
And we come to the end, to what is the projection itself. Both the server that manages the data and the projector, they are usually of different brands, but they have to “speak” the same language, because if the server says “open shovel”, the projector should understand it and “open shovel”.
In the 2D projection there is not much to tell, because it is a projection similar to that of a 35 mm projector, only being digital, it is more perfect, sharper, without the usual problems that happen in 35mm.
Things change when it’s in 3D. For starters, the screen usually has a special material that reflects the light, because when you put the glasses the lightness low enough and although the lamps used in projection are powerful, it shows. That is why the lamp should be set to double the power to compensate for that lack of light.
Unfortunately, in many cases this is not done, either done but the room is too large for light power, giving a negative experience.
Then, depending on the cases, the projector uses a polarizing wheel that directs light from each frame to the corresponding eye, alternating and synchronizing everything so that we do not notice anything at all.
In the case of active systems, the glasses are synchronized with the electronic shutter of the projector, causing the image of each eye to be adjusted, covering the opposite eye, but they are also more expensive and therefore, its implementation is much smaller.
The next step in digital evolution has two ramifications. On the one hand, producing more and more content in 4K, thus obtaining an even sharper image.
On the other hand, the increase in frame rate. Since the beginning, the rate of 24FPS has been maintained, but when digital cinema enters, these limitations no longer exist, and movies can be seen at 48FPS and up to 60FPS
At the projection level, LASER projectors are already being developed and announced, in which the lack of light is not a problem because the concentration of the same exceeds any Xenon lamp. Likewise, the projected image far exceeds current projections, it is practically almost like seeing reality, given the latitude of the projected image.
In addition, because LASER light is already polarized, it is not necessary to polarize it using filters that remove light intensity, so that when viewing the projections with passive (polarized) glasses, they will be seen with the same intensity as without glasses, in addition Not to color the images.