Screening formats guide
- DCP (Digital Cinema Package or digital cinema) is the digital version of the 35mm print: this is the format used by all the multiplexes and a growing number of small cinemas.
- A DCP is a folder of digital files. It can be transported on a USB key (trailers …), a hard drive, internet, etc …
- The images are encoded in JPEG-2000: this is a very efficient compression algorithm, which makes the image lighter without losing details visible to the naked eye.
- A DCP is relatively light: about 300 GB for a feature film, less than 100 GB for a short movie.
- widespread in big cinemas
- widespread in small cinemas
- Exeptionnal quality
- Robustness: the whole DCP chain is very solid. Cinemas equipped to read DCPs are likely to be carefully calibrated
- Reproducible at a low cost: to copy a non-encrypted DCP, simply copy the DCP folder from one medium to another (e.g.: from one hard drive to another).
- Subtitling: it is possible to add subtitles to a DCP without any re-encoding
- Plurality of norms: the DCI (Digital Cinema Initiative), used by Hollywood studios, led to the Interop standard, very rigid in terms of rates and resolutions. SMPTE standards are very recent (2010) and have opened up the standard notably by introducing video frame rates (25, 50 frames per second, etc. …). Not all DCP servers have been updated, and they do not all necessarily support 25 frames per second.
In practice, the DCP servers with which Charbon has to deal from Belgium, France, Germany and Norway, XDC, Barco and Doremi (which represent the vast majority of Europe's DCP servers) totally support the 25fps rate, as well as the 24fps rate.
However, Qube servers only support the 24fps rate.
- Subtitling format: subtitling standards have also evolved from "Interop" to "SMPTE" and there is no guarantee they support this or that standard. Today, the only way of being 100% sure that the subtitles will not be problematic is to test the DCP in the theatre where it will be screened, or to "burn" (embed) them into the image (which requires redoing all the encoding operations).
- Cryptage : les DCP peuvent être cryptés, de manière à n'être lisibles que par un serveur DCP bien précis, à un moment bien précis. Il faut alors délivrer des 'clés' (KDM, Key Delivery Message) qui posent parfois problème quand une erreur se glisse dans un numéro de série, dans une version de sous-titrage, etc...