Visual material logs

September 11, 2008

Notes for Visual Playback systems unit

For a sucesssful set it is vital to have content easily to hand in a format  that will play effectively.  A major part of this is being able to manage content from a wide variety of sources and put it into a format that suits a playing style and different playback systems.  For candidates who wish to  progress in this area it is useful for them to understand that they will often need more than one version of a clip, especially when working digitally. For example; video scratching needs reduced frames per second (fps) , keyframes’ every frame and low resolution, whereas, linear playback, through a large LCD screen, needs high resolution,  a 16:9 aspect ratio, and 25fps. For all candidates It is intended to encourage good practice in this area by the use of the Log in outcome  2,  where more is needed than simply a list of clips to be played.  It should also cover aspects such as;  the original source, location, details on the format of the material, and that it had been play tested, ideally as an early rehearsal of the set, using components that give a good feel  for the final playback system.  This would vary according to the playback system design.  For example, digital material would cover, file ending, CODEC, file size, fps, colour depth, resolution, aspect ratio and number of key frames per second.  These are the main factors that influence playback on common software video decks such Resolume or Motion Dive.  For an analog system say, using  VHS or DV tapes, it could include, labelling tapes clearly so they can be identified in low light and timings of clip positions on a tape. An understanding of SMPTE time code is important when working with taped content, especially when dubbing a set of clips onto a master tape, problems can arise with mixers loosing the signal due to breaks in the time code, often caused by re using tapes or poor dubbing techniques.  Ideally, the Log also acts as a checklist for the candidates’ preparation activities and revises key areas of knowledge from LO1.