HUMA system: Manual under Construction Preparing & planning projects

Introduction

The technical quality and performance of a HUMA interactive screen application depends to great parts on careful preparations and planning, considering both the environment you want to play it in (Runtime computer, graphics board, screen- or projection device etc) and the media foootage you use in it (in terms of resolution, compression etc). The artistical quality solely depends on you. This will therefor give some advice on the technical side only:.


Rules of thumb: Before you start setting up a serious project, take the time and remember these basic rules:
  1. For best quality and performance try to avoid the necessity of scaling, avoid scaling in steps that are not a multiple of 2 in any case!

    Start thinking from the last chain of your project backwards: Where and how will you show it? The pixel resolution of your screen or projector should determine the size of the project. For instance: A 1024*768 pixel screen should be fed with a same size movie rather than with one that is originally 800*600 pixels in size. Allthough the bigger movie will have more data to process, it will deliver a better performance than the scaled one. Especially on slower computers you may consider using footage that is smaller than the output devices resolution in steps of 2 - for the mentioned 1024*768 pixel screen a movie size of 512*384 can deliver good results especially in terms of smoothness of motion (i.e. the framerate that the computer actually manages to perform). However there are parts where it will stay behind a 1024*768 one (with 4 times the ammount of data): Image quality on first hand and second: performance during transitions.

  2. Use the right compressor in the right place!

    Do not use complex, predicting compression algorithms (like Soerenson, MPEG1, 2, or 4 etc) for parts that are under heavy realtime control. For movies you want to scratch or step through or parts with a lot of links and switches between scenes, consider using high keyframe rates or even keyframe only compressors (like Photo-JPEG).
    A Compressor that delivers good overall results for most situations is MotionJPEG-B (given you filter out all the interlacing stripes during rendering).
    Directly using DV footage is fine, allthough it may show some delay on switching scenes on slower machines.