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The DCI Specification for Post Production

The DCI Specification for Post Production. IBC September 11, 2005. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG Alpha channel.

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The DCI Specification for Post Production

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  1. The DCI Specification for Post Production IBC September 11, 2005

  2. Picture • 12bit X’Y’Z’ color • 2048x1080 24p/48p or • 4096x2160 24p • JPEG2000 compression • Sound • 16 channels max; 24bits deep; 48/96Ks/sec • NO COMPRESSION • Subtitles • Text rendering in system or • PNG Alpha channel • Flow and Reels • Elements delivered as package or separately • Broken into “reels” • Playlists reconstruct playout in theater • Packaging (MXF) • Delivery of encrypted elements using MXF • Security / Encryption • Elements encrypted and keys delivered for playout DCI Specification First an overview, then review each section

  3. Simple Functional Flow for Digital Cinema Digital Cinema Distribution Master (DCDM) Digital Cinema Package (DCP) Digital Cinema Server Digital Cinema Projector Similar to Release Print in Film Cans Similar to Dupe Neg Similar to Platter Reel

  4. Digital Cinema Workflow

  5. Digital Cinema Content Preparation Flow and Terminology • Encoding • The process of compressing the image content to condense the large size of the file so it is manageable for distribution and storage • The reverse process of this is called decoding • Encryption • The process of scrambling the content files such that a key is required to unlock the scrambled files

  6. Creating the Digital Cinema Package • Composition • A feature, a trailer, a logo, a short or an advertisement. Any single complete piece of content. • Packaging • Assembling together all of the encoded and encrypted files and wrapping them up into a complete package for shipment.

  7. Packaging Format • Based upon “Reels” • Reels can be electronically spliced together to create a “Composition” (Feature, Trailer, Logo etc.) • Reels include parallel Track Files of different Picture, Sound, Subtitles etc. • Track Files are tied together by Composition Playlists

  8. Example Composition Playlist

  9. Key Management • Key Management • The process of creating and distributing the Keys required to unscramble the content at the authorized auditorium • Key Delivery Message • The mechanism that is used to transport the keys used to unlock the content in the auditorium at play out.

  10. Theatre Playback System • Server • The device that plays back the content in the theatre. Similar to a specialized computer like a Media PC or Tivo for the home. • Show Playlist • The method used to connect the Compositions together in the Theatre to create a complete show.

  11. SHOW PLAY LIST EXIBITION STORAGE Advertisement Start Trailer #1 Composition #1 Start Composition #2 Trailer #2 Start Composition #3 Start Composition #4 Trailer #3 Start Composition #5 Logo Start Composition #6 Start Composition #7 Feature Rating Card Exhibition Show Play List

  12. Basic Security • Watermarking / Fingerprinting • The process of marking the content with unique marks in the picture and the sound to trace the origin of stolen content • Link Encryption • A connection from the server to the projector needs to be scrambled so that someone can not steal the content by tapping into this link. • Logging • The recording of events that take place while a show is played out in the auditorium. Provides audit information back to the studio.

  13. DCI Specification Details

  14. DCI Major Issues • Image resolution and Color • Audio bit depth and sample rates • Compression type and bit rate • Subtitle types and limitations • Packaging and metadata • Security and Key Management

  15. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG Alpha channel WorkFlow and Reels Elements delivered as package or separately Broken into “reels” Playlists reconstruct playout in theater Packaging (MXF) Delivery of encrypted elements using MXF Security / Encryption Elements encrypted and keys delivered for playout DCI Specification

  16. Picture DCDM • Resolution • 2048x1080 OR 4096x2160 Containers • Only active pixels are transported • 24/48 frames per sec for 2k • Reel per Reel configuration • Academy “2 Pop” Leader

  17. DCI RequirementsImage - Dynamics Matt Cowan Entertainment Technology Consultants www.etconsult.com

  18. X’Y’Z’ Color Encodingfor Digital Cinema Distribution Glenn Kennel IBC D-Cinema Update September 11, 2005

  19. Color Encoding • CIE XYZ Color Primaries • Gamma 1/2.6 Transfer Function • 12 bits per channel • Metadata for downstream gamut mapping- describes color gamut that is used in the master

  20. Y Z X Visible and XYZ Visible colors Display Primaries Displayable colors XYZ encoding Space (triangle)

  21. Color Encoding Primaries • XYZ color primaries (1931 CIE standard) • Device independent, colorimetric representation • Encompasses full color gamut • Luminance isolated to one component (Y) Note: x, y, u’ ,v’ refers to the chromaticity coordinates defined by the CIE.

  22. Color EncodingLinear Matrix • R’G’B’ color space of Reference Projector is converted to device-independent X’Y’Z’ color space of DCDM with a linear space matrix 2.6 2.6 [ ] 1/2.6 R’G’B’ RGB XYZ X’Y’Z’

  23. Encoding Transfer Function Where: CV is the resulting Code Value for a color component. L is the luminance output in cd/m2 P is 52.39 (extra headroom reserved for future white point changes to accommodate range from D55 to D65).

  24. Implications for Color Correctors • Color Correctors typically process signals as R’G’B’ code values • Gamma-corrected R’G’B’ video for television • Logarithmic R’G’B’ printing density for film • Color Correctors can also work with X’Y’Z’ data, but controls would need to be recalibrated. • The X’Y’Z’ color space transformation can be implemented in the output of the color corrector.

  25. Cinema Projector Transfer Function P is 52.39 cd/m2 (with headroom)

  26. Cinema Projector Linear Matrix • X’Y’Z’ color space of DCDM is converted to Projector (device specific) RGB color space with a linear matrix 2.6 2.6 [ ] Light Modulators X’Y’Z’ XYZ RGB In this example, the decoding matrix is the inverse of the encoding matrix.

  27. Implications for Projectors • Digital Cinema Projector must have signal processing to convert device-independent X’Y’Z’ code values to its native RGB. • Linearize signal (apply gamma 2.6) • Apply a device-dependent linear matrix • Correct for non-linear modulator response (if necessary) • Calibrate for screen and port glass effects. • As wider gamut projectors are introduced, gamut mapping capability will be necessary for (today’s) smaller gamut projectors.

  28. Color Processing forDigital Intermediatefor both film and digital cinema distribution

  29. DI- Method 1 • Use a 3D LUT in color corrector or external box to mimic film print stock, starting with Printing Density source images • 1 - Color-corrected master is ready for film output (Printing Density) • 2 - Render (“bake in”) the film LUT when outputting the DCDM; Encode color to X’Y’Z’ Mastering Projector R’G’B’ 12 bits Dual 292 DCDM 3D Print Film LUTs (for film matching) Color Encoding To X’Y’Z’ 2 Color Corrections Conforming Scan Film or Import Digital Images Output to film (Laser Film Recorder) Film IN 1 DSM RGB Printing Density

  30. DI- Method 2 • Perform color corrections from source RGB Printing Density to color-corrected R’G’B’ DCDM. • 1 - Color-corrected images are ready for color encoding to X’Y’Z’. • 2 - Use an (inverse film) 3D LUT to convert from R’G’B’ DCDM to RGB Printing Density in a 2nd pass (for film output). Mastering Projector DCDM Color Encoding To X’Y’Z’ Dual 292 1 Color-corrected R’G’B’ DCDM Color Corrections Conforming 2 3D LUT to convert to RGB Printing Density Scan Film or Import Digital Images Film IN DSM RGB Printing Density Output to film (Laser Film Recorder)

  31. Creating Video Masters • Video displays have a smaller color gamut (CCIR 709) • Simple colorimetric conversion could result in clipping of out of gamut colors • Viewing conditions are also very different; pictures look different on a small display in a dim (10%) surround • In theory, a 3D LUT can be built to convert to CCIR 709 color gamut, preserving the look of the picture • Adjusting the transfer function for color appearance • Applying a hue-preserving “soft-clip” for out of gamut colors • A trim pass is still necessary to tune color aesthetics and frame (pan/scan) the picture for the 4:3 full-frame video version

  32. The Reference Projector • X’Y’Z’ encoding (as used here) is output-referred • Faithful color reproduction depends on careful calibration of the mastering projector and cinema projectors • The environment is also critical (screen quality, port glass and ambient light must be controlled) • The Mastering Projector must have the best available black level (sequential contrast) • Otherwise, the cinema projector may unveil unintended details or color errors in the blacks.

  33. X’Y’Z’ Conclusions and Next Steps • Robust, device-independent output-referred color encoding definition • Independent of display primaries and white point • Supports future improvements in color gamut and contrast ratio • DCI StEM test provided a proof of concept • Color transforms were independently verified by several companies • Next step is to test color matching across different projection technologies • Color correctors should implement R’G’B’ to X’Y’Z’ color conversion for DCDM output

  34. JPEG 2000 • No temporal compression • One tile • Extracted 2k from 4k • Max bit rate 250Mb/sec - all formats • ICT required • 9/7 inverse wavelet transfer function • Typical 2k 24 FPS movie: about 150GB, 4k 24 FPS Movie 300GB

  35. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG Alpha channel WorkFlow and Reels Elements delivered as package or separately Broken into “reels” Playlists reconstruct playout in theater Packaging (MXF) Delivery of encrypted elements using MXF Security / Encryption Elements encrypted and keys delivered for playout DCI Specification

  36. Sound DCDM • 16 channels Uncompressed sound 48k/96k, 24bits/channel • Reference Level -20 dBFS • Broadcast WAV file format • Virtual tracks • Able to support multiple languages, commentary, audio headphone tracks • Reel per Reel configuration • “2 Pop” each reel for sync

  37. Channel Mapping

  38. Speaker Placement Diagram L Vertical Front R Screen Left (1) Left Center (7) Center (3) Right (2) Right Center (8) LFE LFE (4) (4) SCREEN Top Center Surround Left Surround (5) Right Surround (6) Center Surround LFE-Rear

  39. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG Alpha channel WorkFlow and Reels Elements delivered as package or separately Broken into “reels” Playlists reconstruct playout in theater Packaging (MXF) Delivery of encrypted elements using MXF Security / Encryption Elements encrypted and keys delivered for playout DCI Specification

  40. Subtitle DCDM • Defining subtitles not a simple task • On Screen • Part of “movie” - Localization, translation • For hard-of-hearing • For foreign translation • Off Screen • Hard-of-hearing, alt language

  41. Supported Subtitles • Timed Text - rendering in the projector or server/media block or alternative display • Selectable fonts and installed fonts • Subpicture - PNG 32bit color alpha overlay • Bit rate limit 20Mb/sec • Bounded rectangles at image resolution • 2K or 4K • Suggested “2 Pop” on spotting cassettes • Suggested “2 pop” subtitle for QC check

  42. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG 8bit Alpha channel WorkFlow and Reels Elements delivered as package or separately Broken into “reels” Playlists reconstruct playout in theater Packaging (MXF) Delivery of encrypted elements using MXF Security / Encryption Elements encrypted and keys delivered for playout DCI Specification

  43. Example Composition Playlist

  44. Packaging Issues • Multiple A/B Reel Configuration • Similar to DI post production • Frame count list for downstream Packaging • Cue generation • FFOA First frame of action • FFOI First frame of Intermission (Optional) • LFOI Last frame of Intermission (Optional) • LFOA Last frame of Action • DCP QC

  45. SHOW PLAY LIST EXIBITION STORAGE Advertisement Start Trailer #1 Composition #1 Start Composition #2 Trailer #2 Start Composition #3 Start Composition #4 Trailer #3 Start Composition #5 Logo Start Composition #6 Start Composition #7 Feature Rating Card Exhibition Show Play List

  46. Distribution Package

  47. Picture 12bit X’Y’Z’ color 2048x1080 24p/48p or 4096x2160 24p JPEG2000 compression Sound 16 channels max; 24bits deep; 48/96Ks/sec NO COMPRESSION Subtitles Text rendering in system or PNG Alpha channel Workflow and Reels Elements delivered as package or separately Broken into “reels” Playlists reconstruct playout in theater Packaging (MXF) Delivery of encrypted elements using MXF Security / Encryption Elements encrypted and keys delivered for playout DCI Specification

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