The Digital Fact Book - Quantel

The approved DCDM is then compressed, encrypted and packaged for distribution as theDigital Cinema Package (DCP). At the theater, it is unpackaged, decrypted and decompressedto create a DCDM* with images visually indistinguishable from those of the original DCDM.Website: www.dcimovies.comDCDMSee DCIDDCPSee DCIDC-SDIAn HD SDI dual link arrangement that is configured to carry live uncompressed DCI-sized2K footage. That is 2048x1080 pixel images at 24P, with 12-bit 4:4:4 sampling in X´Y´Z´color space. This involves a constant data rate of at least 1913 Mb/s, too much for a singleHD-SDI, designed for 1080/60I/30P 10-bit 4:2:2 bit rate of 1248 Mb/s and audio. Hencethe use of a dual link.See also: Dual linkDCT (compression)Discrete Cosine Transform – as a basic operation of MPEG video compression it is widelyused as the first stage of compression of digital video pictures. DCT operates on blocks(hence DCT blocks) of the picture (usually 8 x 8 pixels) resolving them into frequenciesand amplitudes. In itself DCT may not reduce the amount of data but it prepares it forfollowing processes that will. Besides MPEG, JPEG, VC9, WM9 and DV compression dependon DCT. The use of blocks can lead to blocks being visible on screen where data ratesthat are too low are used.See also: DV, ETSI, JPEG, MPEG-2, MPEG-4, WaveletDecibel (dB)Units of measurement expressing ratios of power that use logarithmic scales to give resultsrelated to human aural or visual perception. Many different attributes are given to a referencepoint termed 0 dB – for example a standard level of sound or power with subsequentmeasurements then being relative to that reference. Many performance levels are quotedin dB – for example signal to noise ratio (S/N).Decibels are given by the expression:10 log 10P 1/P 2where power levels 1 and 2 could be audio, video or any other appropriate values.55