Workflows
Post Production Workflows
Introduction
The rapid advances in digital camera technology and the wide range of image capture choices available today has implications both for the Director of Photography, in terms of technical & aesthetic performance, and for the Producer, who wants to know how the choice made affects the Post Production Process in terms of cost, efficiency and ability to produce the planned deliverables.
Both image capture and post route have to be considered together for informed decisions to be made. Above all, involving the chosen post production facility at the earliest possible planning stage in defining and testing the chosen image capture/post production route end to end before shooting begins is the best approach to ensure a successful outcome.
In an overview of the workflow process, it is useful to bear in mind, whether shooting on film or on the latest data recording camera, that the essential work stages are the same – see diagram:-
The Shooting Stage Choices
Film
The well established procedure of shooting on 35mm or Super 16mm film, processing the negative in a Film Laboratory overnight, transferring to tape, with sync sound, for viewing and offline editing the next day, is familiar to most professional film makers. Once the offline is completed, the selected images captured on film are scanned, conformed & graded during post production and output to deliverables.
35mm colour negative film is considered an industry standard against which all other capture mediums are compared. Super 16mm negative film has been and is used extensively for television drama, commercials and lower budget feature films, particularly where portability and wide brightness capture range is needed, or a ‘film look’ is desired.
Video
Images are captured electronically and recorded on video tape in real time. The master tapes can be replayed immediately on set, transferred to editorial where they are edited in offline, then online suites in full resolution, to produce the end product. Cameras range from the small ‘DV’ format through to the latest HD 1920 x 1080 capable cameras. These cameras, in many cases, have sensors similar in size to a Super 16mm film frame.
Data
Data cameras capture individual frames sequentially in a proprietary file format which then have to be extracted by software processing to view them in full resolution, or via a proxy image recorded at the same time. Many data cameras have large sensors comparable with 35mm film and have lens mounts for 35mm film lenses. A Digital Imaging Technician (DIT) is normally employed on set, responsible for processing, checking and backing up the data files (an insurance requirement), ready for post production. Many post facilities now have a data lab and in house technical specialists who handle, store and prepare data files for post production, so the ‘Data Lab’ is a combination of on-set and post house activities.
A tutorial document can be downloaded here, produced by Onsight, which explains file based production in detail. (File-based_production 4 4.pdf)
A document describing the work of a DataLab Service at the Moving Picture Company is can be downloaded here(MPC_DataLab_info.pdf)
Post Production
The post production path followed depends upon the following:-
The delivery requirements – is it a feature film cinema release? Is it for television? If so is it HD or standard definition? What are the future sales requirements? Is it for digital viewing only? What is the budget for post production?
The quality level at which post production is completed could be:-
- Standard definition eg. Digibeta or DVCam,
- High Definition, either Pro Res or full HD (eg. HDCam SR)
- Digital Intermediate at 2K or 4K, for large screen theatrical release.
Taking television drama as a working example, with a HD Post finish and delivery on HDCam SR, the following workflow comparison is shown for Film, HD and Data camera (RED) origination and shows the common stages of offline edit, final EDL, conform/grade & HD deliverables:-
The new stages involved with data cameras are the extraction of the data from RAW or proprietary encoded files (eg RED) firstly at the rushes stage to produce offline edit & preview files at a convenient quality level, then at the final conform stage, returning to the original files and extracting/converting them at full resolution to the common file format being used for the final edit/ conform/grade. In the case of television drama this would be HD files and for feature film digital intermediate this would most commonly be 2K DPX log RGB files, from which final 35mm film masters, digital cinema masters and HD deliverables are produced.
The rapid software development by the major manufacturers of resolution independent non linear editing equipment to handle these new file formats coming from high resolution data cameras, now means the online editor can directly access, select and extract from the camera’s native files using the offline editor’s final Edit Decision List, to create the HD or 2K files needed for the final conform and perform the conform at the same time.
In the case of data cameras with a Bayer Colour Pattern single chip, the process of ‘de-Bayering’ or removing the mosaic pattern of the image sensor RGB filters from the native files, which is part of the file extraction process, can now be re-done at the final conform stage where it is possible to view the results at the highest resolution.
For more information on Avid Based Workflows for RED files see http://www.avid.com/red/REDstepbystep.pdf
For more information on Final Cut Based Workflows for RED see
http://www.red.com/cameras/workflow/
Workflow diagrams for the Arri D21 camera through post for Digital Intermediate at 2K, HD for television and commercials, and file based for commercials are shown at
http://www.arridigital.com/technical/workflow
Daily Cost Comparisons taking into account all the stages through to the DI, between Film, both 35mm and 16mm, and a high end Digital camera, the Arri D21 have been analysed by Arri in the US and are shown at
http://www.arridigital.com/budget
16mm Film and HD
Television channels in the UK currently take the view that 16mm film grain is unsuitable for their HD transmission chains, as the compression devices used are overworked by the random nature of the film grain and their performance suffers, resulting in image artefacts and reduced image quality at the consumer destination. As compression performance improves this barrier to 16mm could disappear, but in the meantime there have been significant developments in grain/noise reduction software capable of eliminating film grain without introducing artefacts or losing sharpness, which offer possible solutions to the broadcaster’s concerns today.
Details of the Arri Relativity software may be found at
http://www.arri.de/digital_intermediate_systems/relativity.html
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