Xref: utzoo comp.windows.x:34342 comp.graphics.visualization:395 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!jarthur!uunet!psitech!jim From: jim@psitech.com (Jim Rothrock) Newsgroups: comp.windows.x,comp.graphics.visualization Subject: Re: [xpert...] free video movies Message-ID: <539@psitech.com> Date: 21 Mar 91 16:57:23 GMT References: <1991Mar15.183911.18550@kodak.kodak.com> <1991Mar16.235110.14802@ox.com> Followup-To: comp.windows.x Organization: PsiTech, Fountain Valley, CA Lines: 34 In article kas@cs.aber.ac.uk (Kevin Sharp) writes: >>>>>> On 16 Mar 91 23:51:10 GMT, tiefel@sunshine.Kodak.COM (Lenny Tiefel) said: >Lenny> What image format would be most useful? >Lenny> Example: gif > > >None of popular image formats would be suitable. What you need is a >movie format. > >One obvious thing you do in a movie format is not to replicate data in >consecutive frames. This can have the advantage of both reducing the >data size and increasing the speed at which it can be played. For >example using an encoding where only changes in the image are recorded >you don't redraw those bits that don't change. This fits in very >tidily with a run length encoding scheme. On the Amiga, most programs store their data in IFF files, which can contain several kinds of data. For example, an IFF file can contain a "form" ILBM, which is a bitmapped image. 8SVX is digitized sound data, and SMUS is music data. There is also an *ANIM* format, which is a sequence of compressed images. Only the differences between the frames are stored, and (I believe) several different compression methods can be used, depending on the type of image. e.g. run-length compression works well on 3D animations made up of flat-shaded polygons, but isn't as useful for photorealistic images containing very few contiguous sequences of pixels with the same color. The ANIM documentation and ANIM players are readily available (on the Amiga, at least). Someone should look into using this format for the movie images. -- Jim Rothrock | Disclaimer: My opinions do *not* represent the opinions jim@psitech.com | of PsiTech, Inc.